September 2021 News and research items
Research_News_20_09_2021
Further links and discussion can be found at the groups/links below
Astronomy in New Zealand - Facebook
https://www.facebook.com/groups/5889909863/
Astronomy in New Zealand - Groups.io
https://groups.io/g/AstronomyNZ
Google Group
https://groups.google.com/g/nzastrochat
Astronomy in Wellington
https://www.facebook.com/groups/11451597655/
Blogger Posts
http://laintal.blogspot.com/
Reddit
https://www.reddit.com/user/Edwin_Rod_NZ
Quaroa
https://www.quora.com/q/astronomyinnewzealand
Twitter
https://twitter.com/EdwinRodham
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Research papers
A record of the final phase of giant planet migration fossilized in the asteroid belt's orbital structure
https://arxiv.org/abs/1912.02833
A search of the full six years of the Dark Energy Survey for outer Solar System objects
https://arxiv.org/abs/2109.03758
The orbit of Planet Nine
https://arxiv.org/abs/2108.09868
A multispecies pseudoadiabat for simulating condensable-rich exoplanet atmospheres
https://arxiv.org/abs/2108.12902
Populating the brown dwarf and stellar boundary
https://arxiv.org/abs/2107.03480
Postulating Exoplanetary Habitability via a Novel Anomaly Detection Method
https://arxiv.org/abs/2109.02273
Stellar Gravitational Lens Engineering for Interstellar Communication
https://arxiv.org/abs/2109.08657
Genome of a middle Holocene hunter-gatherer from Wallacea
https://www.nature.com/articles/s41586-021-03823-6
No Large Dependence of Planet Frequency on Galactocentric Distance
https://arxiv.org/abs/2108.11450
Observation of Time-Crystalline Eigenstate Order on a Quantum Processor
https://arxiv.org/abs/2107.13571
First Estimation of Global Trends in Nocturnal Power Emissions Reveals Acceleration of Light Pollution
https://www.mdpi.com/2072-4292/13/16/3311/htm
An Improved Approach to Orbital Determination and Prediction of Near-Earth Asteroids
https://arxiv.org/abs/2109.07397
Exomoons in Systems with a Strong Perturber
https://arxiv.org/abs/2105.00034
Obliquity Evolution of Circumstellar Planets in Sun-like Stellar Binaries
https://arxiv.org/abs/1911.08431
Exosphere Modeling of Proxima b
https://arxiv.org/abs/2109.06963
Early habitability and crustal decarbonation of a stagnant-lid Venus
https://arxiv.org/abs/2109.08756
Analyzing the Habitable Zones of Circumbinary Planets
https://arxiv.org/abs/2109.08735
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Interesting News items
Losing The Sky
https://andyxlastro.me/losing-the-sky
Bringing woolly mammoths back from extinction
https://theconversation.com/bringing-woolly-mammoths-back-from-extinction-might-not-be-such-a-bad-idea-ethicists-explain-167892
Under New Zealand's Dark Skies, Insects Recover and Humans Reconnect with a Lost View
https://www.atlasobscura.com/articles/new-zealand-dark-sky-reserve
The orbit of Planet Nine
http://findplanetnine.blogspot.com/2021/08/the-orbit-of-planet-nine.html
Want to find Planet Nine?
https://www.syfy.com/syfywire/want-to-find-planet-nine-heres-a-treasure-map
Why Can’t We Find Planet Nine?
https://www.quantamagazine.org/why-cant-we-find-planet-nine-20180703
The orbit of Planet Nine
https://arxiv.org/abs/2108.09868
A search of the full six years of the Dark Energy Survey for outer Solar System objects
https://arxiv.org/abs/2109.03758
Footage of last-known surviving Tasmanian tiger remastered and released in 4K colour
https://www.abc.net.au/news/2021-09-07/tasmanian-tiger-footage-digitised-and-colourised/100439870
An exciting return to the Moon
http://spaceref.com/moon/viper-rover-to-land-near-nobile-region-of-moons-south-pole.html
Dark skys desert climates, great location to get away from it all, Space to build your own observatory with your one Stonehenge too. What’s not to like?
An unusual house with its own Stonehenge lists in New Mexico for just over NZ$1m
https://www.stuff.co.nz/life-style/homed/the-high-life/300400434/an-unusual-house-with-its-own-stonehenge-lists-in-new-mexico-for-just-over-nz1m
10 Atole Way, Placitas, NM 87043
https://www.zillow.com/homedetails/10-Atole-Way-Placitas-NM-87043/2087974372_zpid
Exomoons: The Binary Star Factor
https://www.centauri-dreams.org/2021/09/14/exomoons-the-binary-star-factor/comment-page-1/#comment-232690
Exomoons in Systems with a Strong Perturber
https://arxiv.org/abs/2105.00034
Obliquity Evolution of Circumstellar Planets in Sun-like Stellar Binaries
https://arxiv.org/abs/1911.08431
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Updates from Andrew B,
Mars.
Imaged: Thursday 26th August 2021. Sol 184.
Images with the MastCam Z (Zoom) Camera.
First Image. A nice view of a small part of ridge at the Citadelle site, with the Neretva Vallis Delta (previously known informally as the Jezero Crater Delta), looking a lot closer in the background.
Second Image: MastCam Z (Zoom) image looking down the Neretva Vallis in the horizon.
The image looks along part of the Neretva Vallis (the large gap in the Jezero Crater wall to the west where the inbound river flowed into the Jezero Carter), which hopefully in about two years time will be where Perseverance will be driving along. The bottom of Neretva Vallis will hopefully reveal how this ancient martian river ran before drying out about 3.5 billion years ago.
Taken & 12:47 & 12:49 HRS LMST. Local Mars Standard Time at Jezero Crater.
Jezero Crater, Syrtis Major Quadrangle.
MastCam Z (Zoom) Camera.
Text: Andrew R Brown.
NASA / JPL-Caltech / ASU / MSSS / LANL / CNES / IRAP. Mars Perseverance Rover.
Zhurong Rover.
Monday 30th August 2021.
New image. New 360 degree panorama from within the Complex Terrain, which includes tiny impact craters, more dunes and more boulders.
Made some slides from crops from the new panorama.
As of Monday 30th August 2021, the Zhurong Rover has operated for 100 sols and driven 1,064 metres since landing.
Technically the ninety sol warranty was achieved, however Zhurong continues to operate very well indeed and is still in great shape. The mission is to continue for the forseeable future.
The Tianwen 1 orbiter (Tianwen is mandarin for Questions to Heaven), which has been acting as mostly a relay for the Zhurong Rover has lowered slightly into a 7 hour & 48 minute Areocentric (Mars centred) orbit from the 8 hour & 12 minute one. This is to facilitate it's own science mission whilst still very frequently relaying data from the Zhurong Rover.
Zhurong Rover is approaching a suspected ancient sea bed and may also in time visit a truly ancient martian mud volcano.
Note how much smoother and less rocky than from much further north in Utopia Planitia as seen by the historic NASA Viking 2 lander in 1977. Viking 2 landed within the ejecta from the 104 KM wide Mie Crater which was about 200 KM to the east. Zhurong Rover did not land close enough to any large craters, hence so few rocks.
Zhurong was a Fire God in ancient China.
Southwest Utopia Planitia. Amenthes Quadrangle.
Position confirmed as 109.9 East, 25.1 North.
Utopia Planitia (No Where Plain) is a huge lava flooded impact basin, one of the largest if not the largest known impact crater in the solar system. It is about 3,300 KM / 2,051 miles wide and parts of it are within the Casius, Amenthes, and Cebrenia quadrangles in the northern hemisphere of Mars.
Very different to the views from Viking 2 which is 1,721 KM / 1,069 miles to the NE, also in Utopia Planitia, further north in Cebrenia Quadrangle.
Text: Andrew R Brown.
China National Space Administration / CNSA.
Zhurong Rover.
Friday 10th September 2021.
Mars InSight / Interior Exploration using Seismic Investigations, Geodesy and Heat Transport Lander.
A 2 KM wide fracture within the Cerberos Fossae imaged by the ESA Trace Gas Orbiter spacecraft using the CaSSIS Camera.
European Space Agency, ExoMars, Trace Gas Orbiter, CaSSIS (Colour and Stereo Surface Imaging System) camera.
Science results have been released concerning the Mars InSight / Interior Exploration using Seismic Investigations, Geodesy and Heat Transport Lander which successfully landed on the lava plains within south west Elysium Planitia, Elysium Quadrangle on: Monday 26th November 2018.
Interesting results they are too.
The SEIS / Seismometer and the RISE / Rotation and Interior Structure Experiment have determined the following about Mars.
1). Mars has a thinner expected crust, could be locally rather than globally. The crust appears to have at leat two sub layers with a total depth of about 20 KM / 12 miles. If the third sublayer is confirmed, the depth could be 37 KM / 23 miles.
2). Mars appears to have a mantle 1,540 KM / 957 miles deep, and appears to be fairly uniform in composition and is single layered.
3). Mars also appears to have a molten iron core, also to be an alloy with lighter elements. The core is 3,660 KM / 2,274 miles wide and currently appears to be a single layered core, like the Moon.
4). All Marsquakes detected to date originate from the Cerberos Fossae area some 1,519 KM / 944 miles to the east. These along with all other Marsquakes detected to date originate within the same area, proving that Cerberus Fossae is a geologically active region, with perhaps magma (unerupted molten rock) moving around deep under the martian crust there. Another possiblity is that these fractures could also result from the cooling of the interior of Mars, cracking the crust, much like the Rupes on Mercury.
I have attached some readings and some of my favourite Mars InSight images and the new TGO Cassis image.
LMST = Local Mars Standard Time in western Elysium Planitia.
45 degree wide view from the Instrument Deployment Camera / IDC of the Mars InSight lander deck with the volcanic plains in the background to the horizon of Elysium Planitia, Elysium Quadrangle.
120 degree wide views from the Instrument Context Camera of the Seismometer thermal & wind shield and lava plains to the south.
Note how the plains of Elysium Planitia here are remarkably similar to those in SW Utopia Planitia some 1,922 KM / 1,194 miles away as seen by the China National Space Administration / CNSA Zhurong Rover.
Power issues have been a huge concern for Mars inSight in recent months as the solar arrays have become increasingly coated in dust and Mars has just passed through Aphelion, the furthest point from the Sun at a distance of about 250.50 million KM / 156.65 million miles from the Sun. Mars at Aphelion occured on: Tuesday 13th July 2021.
The next Mars Perihelion (closest point to the Sun) will occur on: Tuesday 21st June 2022.
Firstly the dust issue has been somewhat alleviated by a very balsy but appearing to be largely successful plan of the scoop to dump small quantities of duricrust on the deck next to the arrays and allowing the winds to pick up particles from the duricrust, blow them across the arrays knocking off dust particles. It is working and the power output from the arrays has increased a little and continuing to do so.
Perhaps the powering down of the science instruments can be postponed or even not at all. The more seismic & RISE data, the better for sure. The cameras too can keep capturing images.
It was hoped that dust devils would at times pass over InSight and they would remove dust from the solar panels. This happened fairly frequently with the Mars Exporation Rovers, MER A Sprit and MER B Opportunity as well as the Phoenix Mars Lander. All three had vastly extended operational missions in part due to this.
However, this has not happened with Mars InSight Lander.
Whilst it is late Spring in the northern hemisphere on Mars now (InSight landed at about 4.5 North, well within the martian tropics between the equator and the Tropic of Aquarius, Mars's northern tropic), the increased distance towards Aphelion is offsetting the higher rising Sun. It was the Martian Solstice, northern Summer, southern Winter on: Tuesday 25th August 2021.
Text: Andrew R Brown.
IRIS / Incorporated Research Institutions for Seismology. Earth & Mars.
NASA / JPL-Caltech. Mars InSight.
Interior Exploration using Seismic Investigations, Geodesy and Heat Transport.
ESA/Roscosmos/ExoMars/CaSSIS/UniBE. ExoMars, Trace Gas Orbiter spacecraft.
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RASNZ
Royal Astronomical Society of New Zealand
eNewsletter: No. 249, 20 September 2021
Affiliated Societies are welcome to reproduce any item in this email newsletter or on the RASNZ website www.rasnz.org.nz in their own newsletters provided an acknowledgement of the source is also included.
Contents
1. James Webb Space Telescope Launch Delayed
2. RASNZ Beanies
3. The Solar System in October
4. Variable Star News
5. Science and Space Podcasts
6. Citizen Science Astronomy Projects
7. Hydrogen-Burning White Dwarfs
8. AAS Journals Open Access in 2022
9. Record-Breaking Atira Discovered
10. Saturn's Sloppy Core
11. New Type of Dark Energy?
12. Chicxulub crater Anniversary
13. Gifford-Eiby Lecture Fund
14. How to Join the RASNZ
15. Quote
1. James Webb Space Telescope Launch Delayed
NASA's long-awaited and high-powered James Webb Space Telescope won't begin observations this year after NASA and its counterpart the European Space Agency (ESA) announced another launch delay.
In coordinated statements, the two agencies announced that the observatory is now targeting a launch on Dec. 18, more than six weeks after its previously set lift-off date. The highly-anticipated project has racked up consistently escalating budget and schedule overruns since development began in the 1990s.
"We now know the day that thousands of people have been working towards for many years, and that millions around the world are looking forward to," Günther Hasinger, ESA's director of science, said in an agency statement. "Webb and its Ariane 5 launch vehicle are ready, thanks to the excellent work across all mission partners. We are looking forward to seeing the final preparations for launch at Europe's Spaceport."
The observatory's most recent target launch date was Oct. 31, but it had long been suggested that the telescope, also known as JWST, would miss that schedule. In June, Thomas Zurbuchen, who serves as NASA's associate administrator for science, admitted that the timeline for the launch was looking tricky.
The observatory has not yet shipped from its current location in California to ESA's launch site at Kourou in French Guiana, and estimates suggest that the observatory needs about 10 weeks turnaround time from shipping out until launch. Additionally, the Ariane 5 rocket that will launch the observatory only began its journey from Europe to South America for the flight in mid-August, according to an ESA statement.
Ariane 5 made its first flight in nearly a year on July 30. Arianespace, which builds the rocket, had benched the launcher after two 2020 flights were successful but experienced nose cone anomalies. The rocket has another preparatory flight to make later this month before it will be clear to launch the new observatory.
Once the James Webb Space Telescope launches, the spacecraft will spend about a month traveling the 1.5 million km out to its destination, the second Lagrange point (L2). Here, the observatory can enjoy a relatively stable "parking spot" orbit on the opposite side of Earth from the sun. The location is crucial for the telescope, which must remain well shielded from the heat that would interfere with the infrared capabilities on the observatory.
The telescope's instruments won't turn on until two or three months after launch, and typical science won't begin until about six months after launch, according to ESA.
See Meghan Bartels original article with pictures at https://www.space.com/james-webb-space-telescope-launch-december-2021
2. RASNZ Beanies
Astronz advises that a limited stock of the RASNZ Centennial Beanies have arrive in and are now available on the Astronz website at
https://astronz.nz/products/rasnz-centenary-beanie .
3. The Solar System in October
Dates and times shown are NZDT (UT + 13 hours). Rise and Set times are for Wellington. They will vary by a few minutes elsewhere in NZ. Data is adapted from that shown by GUIDE 9.1.
THE SUN and PLANETS in OCTOBER, Rise & Set, Magnitude & Constellation
OCT 1 NZDT OCT 31 NZDT
Mag Cons Rise Set Mag Cons Rise Set
SUN -26.7 Vir 6.53am 7.28pm -26.7 Lib 6.06am 8.02pm
Mercury 1.6 Vir 7.15am 8.56pm -0.8 Vir 5.35am 6.34pm
Venus -4.3 Lib 8.37am 11.24pm -4.6 Oph 8.25am 12.12am
Mars 1.7 Vir 7.03am 7.37pm 1.7 Vir 5.49am 7.20pm
Jupiter -2.7 Cap 3.22pm 5.20am -2.5 Cap 1.23pm 3.22am
Saturn 0.5 Cap 2.01pm 4.34am 0.6 Cap 12.04pm 2.37am
Uranus 5.7 Ari 10.17pm 8.33am 5.6 Ari 8.14pm 6.32am
Neptune 7.8 Aqr 5.49pm 6.29am 7.8 Aqr 3.47pm 4.29am
Pluto 14.5 Sgr 12.54pm 3.57am 14.6 Sgr 10.56am 2.00am
OCT 1 NZDT OCT 31 NZDT
TWILIGHTS morning evening morning evening
Civil: start 6.28am, end 7.54pm start 5.40am, end 8.30pm
Nautical: start 5.55am, end 8.27pm start 5.03am, end 9.07pm
Astro: start 5.21am, end 9.01pm start 4.25am, end 9.46pm
OCTOBER PHASES OF THE MOON, times NZDT & UT
New Moon: Oct 7 at 12.05am (Oct 6, 11:05 UT)
First quarter: Oct 13 at 4.25pm (03:25 UT)
Full Moon: Oct 21 at 3.57am (Oct 20, 14:57 UT)
Last quarter Oct 29 at 9.05pm (Oct 28, 20:05 UT)
THE PLANETS in OCTOBER 2021
VENUS is a brilliant object in the evening sky. It is at its greatest angular distance from the Sun at the end of October when it will set over 4 hours after the Sun, shortly after midnight (NZDT). So it is readily visible all evening. In mid-October Venus passes the first magnitude star, Antares, the two being about 1.5° at their closest.
MERCURY and MARS are both going to be more or less unobservable during October. Both are at conjunction with the Sun, Mars on the 8th and Mercury 36 hours later. Following conjunction they both move into the morning sky rising in twilight shortly before the Sun.
JUPITER and SATURN are both easily visible in the evening sky. They rise early afternoon and set well after midnight, with Jupiter being about 80 minutes behind Saturn. Both planets are stationary during October, Saturn on the 11th and Jupiter a week later.
The moon will be a little over 3° above Saturn on the 14th and a similar distance from Jupiter on the 15th.
URANUS, NEPTUNE and PLUTO are all becoming evening objects. Uranus will rise early in the evening during October, barely a quarter hour after the Sun sets by the end of the month. By that date, Neptune will be up by mid afternoon while PLUTO rises near midday all month.
POSSIBLE BINOCULAR ASTEROIDS in OCTOBER
OCT 1 NZDT OCT 30 NZDT
Mag Cons transit Mag Cons transit
(1) Ceres 8.3 Tau 5.24am 7.7 Tau 3.19am
(2) Pallas 8.9 Aqr 11.35pm 9.5 Aqr 9.28pm
(4) Vesta 7.9 Vir 3.00pm 7.8 Lib 2.02pm
(7) Iris 9.4 Gem 7.47am 9.1 Gem 6.33am
CERES, in Taurus is stationary on October 8 after which date it starts heading back towards Aldebaran. By the 31st the two are less than half a degree apart. The asteroid is a late evening object, rising at 12.17am on the 1st and 10.15 pm on the 31st.
PALLAS, in Aquarius, rises at 5.14pm on the 1st and at 2.48pm on the 31st.
VESTA is an early evening object crossing from Virgo to Libra on the 3rd. It sets at 9.37pm on the 1st and 9.00pm on the 31st, an hour after the Sun
IRIS is crossing Gemini in October. It rises at 3.10am on the 1st and 1.43am on the 31st, so is very much a morning sky object.
-- Brian Loader
4. Variable Star News
RS Ophiuchus Update
The outburst of recurrent nova RS Ophiuchus was reported on in the August RASNZ Newsletter. From its stable brightness at visual magnitude 11.2 it rapidly rose to magnitude 4.6 and then dropped quickly, in a week, to about magnitude 7.0. Since then, typical of the behaviour of novae, the star has declined more slowly, and in the following month is now at about magnitude 9.5. The star has been observed by over 1200 observers at a number of different wavelengths. The light curve can be plotted from the observations in the AAVSO website database (Go to bottom of Home page. Enter RS Oph in Tile “Pick A Star”. Select “Recent Observations”. Choose a time period of 60 days or so).
-- Alan Baldwin
5. Science and Space Podcasts
Ernest Rutherford’s Place in Science
Rutherford, probably our most famous scientist, won his Nobel Prize in Chemistry for work on radio-activity, even though he went on to make even greater breakthroughs in Physics on the structure of the atom. On the occasion of the 150th Anniversary of Ernest Rutherford’s birth, Radio NZ broadcast this interview with Allan Blackman, Professor of Chemistry, AUT, on his assessment of Rutherford’s contribution to science (9 min). His brief descriptions of Rutherford’s experiments are worth listening to.
https://www.rnz.co.nz/national/programmes/ninetonoon/audio/2018809647/was-ernest-rutherford-ripped-off
The other two New Zealanders who have won a Nobel Prize are Maurice Wilkins and Alan MacDiarmid. Wilkins developed the imaging techniques that revealed the helix structure of DNA. MacDiarmid, after years of research, discovered how to make polymers conductive.
Starlink Satellites
Elon Musk's Starlink satellites are a wondrous sight - and also a slightly disturbing one. ... From The Detail, 5:00 am on 3 March 2021 and repeat Sunday 12 September 2021. Interview with John Kirkley, Auckland Stardome Educator (22 min).
https://www.rnz.co.nz/audio/player?audio_id=2018785303
RNZ Synopsis: When satellites become star pollution
https://www.rnz.co.nz/programmes/the-detail/story/2018785303/when-satellites-become-star-pollution
New Zealand in Space. A review of NZ space activities.
Broadcast 'Our Changing World', 23 Nov 2017, 9:05 pm (31 min).
Features Rocket Lab’s Peter Beck, Nicholas Rattenbury (Auckland University), Sergei Gulyaev (Auckland University of Technology) and the NZ Space Agency and Centre for Space Science Technology based in Alexandra. Sets out the foundations which are currently being built on.
https://www.rnz.co.nz/national/programmes/ourchangingworld/audio/2018622454/new-zealand-in-space
-- Items selected by Alan Baldwin
6. Citizen Science Astronomy Projects
Tim Banks writes:
I'd imagine RASNZ members are already participating with Zoonuniverse projects --- these crowdsourcing projects can be quite fun, plus it doesn't really matter how much time you put in, your effort is a contribution. I've participated in some of these, on topics such as searching satellite images for MH70 in the early days of its loss through to identifying Martian landscapes. They're quite a nice way to get high school students and the general public involved in research.
Once people are using Zoonuniverse they'll spot the other astronomy projects on the site: https://science.nasa.gov/citizenscience
7. Hydrogen-Burning White Dwarfs
Could dying stars hold the secret to looking younger? New evidence from the NASA/ESA Hubble Space Telescope suggests that white dwarfs could continue to burn hydrogen in the final stages of their lives, causing them to appear more youthful than they actually are. This discovery could have consequences for how astronomers measure the ages of star clusters.
The prevalent view of white dwarfs as inert, slowly cooling stars has been challenged by observations from the NASA/ESA Hubble Space Telescope. An international group of astronomers have discovered the first evidence that white dwarfs can slow down their rate of ageing by burning hydrogen on their surface.
“We have found the first observational evidence that white dwarfs can still undergo stable thermonuclear activity,” explained Jianxing Chen of the Alma Mater Studiorum Università di Bologna and the Italian National Institute for Astrophysics, who led this research. “This was quite a surprise, as it is at odds with what is commonly believed.”
White dwarfs are the slowly cooling stars which have cast off their outer layers during the last stages of their lives. They are common objects in the cosmos; roughly 98% of all the stars in the Universe will ultimately end up as white dwarfs, including our own Sun. Studying these cooling stages helps astronomers understand not only white dwarfs, but also their earlier stages as well.
To investigate the physics underpinning white dwarf evolution, astronomers compared cooling white dwarfs in two massive collections of stars: the globular clusters M3 and M13. These two clusters share many physical properties such as age and metallicity but the populations of stars which will eventually give rise to white dwarfs are different. In particular, the overall colour of stars at an evolutionary stage known as the Horizontal Branch are bluer in M13, indicating a population of hotter stars. This makes M3 and M13 together a perfect natural laboratory in which to test how different populations of white dwarfs cool.
“The superb quality of our Hubble observations provided us with a full view of the stellar populations of the two globular clusters,” continued Chen. “This allowed us to really contrast how stars evolve in M3 and M13.”
Using Hubble’s Wide Field Camera 3 the team observed M3 and M13 at near-ultraviolet wavelengths, allowing them to compare more than 700 white dwarfs in the two clusters. They found that M3 contains standard white dwarfs which are simply cooling stellar cores. M13, on the other hand, contains two populations of white dwarfs: standard white dwarfs and those which have managed to hold on to an outer envelope of hydrogen, allowing them to burn for longer and hence cool more slowly.
Comparing their results with computer simulations of stellar evolution in M13, the researchers were able to show that roughly 70% of the white dwarfs in M13 are burning hydrogen on their surfaces, slowing down the rate at which they are cooling.
This discovery could have consequences for how astronomers measure the ages of stars in the Milky Way. The evolution of white dwarfs has previously been modelled as a predictable cooling process. This relatively straightforward relationship between age and temperature has led astronomers to use the white dwarf cooling rate as a natural clock to determine the ages of star clusters, particularly globular and open clusters. However, white dwarfs burning hydrogen could cause these age estimates to be inaccurate by as much as 1 billion years.
“Our discovery challenges the definition of white dwarfs as we consider a new perspective on the way in which stars get old,” added Francesco Ferraro of the Alma Mater Studiorum Università di Bologna and the Italian National Institute for Astrophysics, who coordinated the study. “We are now investigating other clusters similar to M13 to further constrain the conditions which drive stars to maintain the thin hydrogen envelope which allows them to age slowly”.
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Astronomers use the word “metallicity” to describe the proportion of a star which is composed of elements other than hydrogen and helium. The vast majority of matter in the Universe is either hydrogen or helium — to take the Sun as an example, 74.9% of its mass is hydrogen, 23.8% is helium, and the remaining 1.3% is a mixture of all the other elements, which astronomers refer to as “metals”.
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See the original press release at https://esahubble.org/news/heic2108/?lang
-- Thanks to Karen Pollard for passing it along.
8. AAS Journals Open Access in 2022
Research results in astronomy, solar physics, and planetary science are about to become more widely accessible to scientists and the public alike. The American Astronomical Society (AAS), a leading non-profit professional association for astronomers, today announced the switch of its prestigious journals to fully open access (OA) as of 1 January 2022.
Under this change, all articles in the AAS journal portfolio will be immediately open for anyone to freely read. The transition will affect the Astronomical Journal (AJ), the Astrophysical Journal (ApJ), Astrophysical Journal Letters (ApJL), and the Astrophysical Journal Supplement Series (ApJS); the Planetary Science Journal, the AAS’s newest journal published in partnership with its Division for Planetary Sciences, is already fully open access.
The AAS’s community-owned, peer-reviewed journals collectively publish more than 4,000 articles each year from a diverse and international authorship, and they consistently feature some of the most-read and most-cited research results in the astronomical sciences. The transition to OA will allow everyone to access this high-quality and trusted research, and it will offer scientists low-cost fully OA options for publishing their research in astronomy and related disciplines. The new publishing policy aligns with ongoing efforts by the Society to centre diversity, equity, and inclusion in its work within the astronomical community.
Under the new OA model, subscription charges and paywalls will be entirely eliminated, providing readers with immediate universal access to all past and future research articles published in the AAS journals. Reasonable article publication charges will cover the journals’ operating costs, and the Society will also enhance its waiver and discount program, providing generous assistance to eligible authors who don’t have sufficient funding.
As of January 2022, the AAS’s journal portfolio will be fully compliant with recent open-science government and funding-body mandates like Europe’s Plan S, UK Research and Innovation's OA policy, and others. Moreover, US research funding agencies such as NASA and the National Science Foundation (NSF) have expressed support for OA publishing. NASA and NSF generally cover publication costs as allowable expenses for grants, which would include costs of the new OA model.
Since 2017, the AAS journals have provided a hybrid OA option, allowing authors the choice to publish their articles traditionally or OA. “We’ve seen that articles published open access in our journals are on average more widely cited than those that are paywalled,” says AAS Chief Publishing Officer Julie Steffen. “The OA article describing the Event Horizon Telescope’s observations of the ‘shadow’ of a black hole, for instance, has been downloaded an astounding 340,000 times by people all over the world. The transition of all our journals from hybrid to fully OA in January will provide this same wide audience access to the entire cosmos.”
-- Thanks to Graeme Jonas for passing along this news.
9. Record-Breaking Atira Discovered
A newly discovered asteroid has broken many records in our Solar System. The object, now designated 2021 PH27, was discovered by Scott Sheppard on 13 August 2021, using the wide-field DECam imager mounted on the 4-metre Blanco Telescope at Cerro Tololo.
What makes this asteroid really unique is its extremely small orbit, and short orbital period. It orbits the Sun in less than 4 months (115 days to be precise), surpassed among the known objects only by planet Mercury with its 89 days. The semiaxis of its orbit is consequently the smallest among the known asteroids, at 0.46 au.
A direct consequence of its orbit is its challenging observability. It always remains very close to the Sun, and therefore can only be observed from Earth during very short time windows around local twilight. Also, its location in the sky makes it almost unobservable from the Northern Hemisphere, with Southern tropical locations being favoured. Because of these constraints, only less than 5 days of observations had been initially obtained, resulting in a poorly determined orbit that would have made a recovery during the next apparition quite challenging.
To improve the orbital information European Space Agency observers made follow-up observation of the object on 30 August, twelve days after the latest reported astrometric measurement. The object was detected with a 36 cm telescope in Namibia, operated by the 6ROADS team. At a latitude of 23° South of the equator, its location is ideal for this particular object, and allowed us to detect it at an elevation of 18° above the local horizon, while at a solar elongation of just 33°.
Adding the corresponding astrometry to the orbital solution leads to an improvement of the uncertainties on all orbital elements of about an order of magnitude. The uncertainty of its sky position during the next apparition, in 2022, is similarly improved, going from a few degrees to just a few arcminutes, and ensuring that the object will likely not be lost in the future.
-- See the original article with orbit diagram at https://neo.ssa.esa.int/-/latest-news
10. Saturn's Sloppy Core
The rings of Saturn may hold clues into the planet's soupy, mushy core, scientists say. Saturn's rings aren't just a beautiful adornment — scientists can use the feature to understand what's happening deep inside the planet.
By using the famous rings like a seismograph, scientists studied processes in the planet's interior and determined that its core must be "fuzzy." Instead of a solid sphere like Earth's, the core of Saturn appears to consist of a 'soup' of rocks, ice and metallic fluids that slosh around and affect the planet's gravity.
The new study used data from NASA's Cassini mission, which orbited Saturn and its moons for 13 years between 2004 and 2017. In 2013, data from the mission revealed for the first time that Saturn's innermost ring, the D-ring, ripples and swirls in ways that cannot be entirely explained by the gravitational influences of the planet's moons. The new study looked at these motions in Saturn's rings in greater detail to gain insight into the processes in its interior.
"We used Saturn's rings like a giant seismograph to measure oscillations inside the planet," Jim Fuller, assistant professor of theoretical astrophysics at Caltech and one of the authors of the paper said in a statement. "This is the first time we've been able to seismically probe the structure of a gas giant planet, and the results were pretty surprising."
Not only does the planet's core seem sludgy, it also appears to extend across 60% of the planet's diameter, making it much larger than previously estimated.
The analysis showed that Saturn's core might be about 55 times as massive as the entire planet Earth. Of the total mass of the core, 17 Earth masses are made of ice and rock, with the rest consisting of a hydrogen and helium-based fluid, the study suggests.
The lead author of the study, Christopher Mankovich, a postdoctoral scholar research associate in planetary science who works in Fuller's group, explained that the motions in the core cause Saturn's surface to constantly ripple. These surface waves create minuscule changes in the planet's gravity that subsequently affect the rings.
"Saturn is always quaking, but it's subtle," Mankovich said in the statement. "The planet's surface moves about a meter every one to two hours like a slowly rippling lake. Like a seismograph, the rings pick up the gravity disturbances, and the ring particles start to wiggle around."
According to the scientists, the nature of those ring ripples suggests that the core, despite its sloshing, is composed of stable layers of various densities. Heavier materials sit around the centre of the planet and don't mix with the lighter materials closer to the surface.
The research is described in a paper published in the journal Nature on August 16.
-- See all of Tereza Pultarova's article with pictures at https://www.space.com/saturn-rings-study-reveals-soupy-core
There is another summary at
https://skyandtelescope.org/astronomy-news/saturn-fuzzy-core/
11. New Type of Dark Energy?
Hints of a previously unknown, primordial form of dark energy could explain why the cosmos now seems to be expanding faster than theory predicts. Cosmologists have found signs that a second type of dark energy — the ubiquitous but enigmatic substance that is pushing the current Universe’s expansion to accelerate — might have existed in the first 300,000 years after the Big Bang.
Two separate studies — both posted on the arXiv preprint server in the past week — have detected a tentative first trace of this ‘early dark energy’ in data collected between 2013 and 2016 by the Atacama Cosmology Telescope (ACT) in Chile. If the findings are confirmed, they could help to solve a long-standing conundrum surrounding data about the early Universe, which seem to be incompatible with the rate of cosmic expansion measured today. But the data are preliminary and don’t show definitively whether this form of dark energy really existed.
“There are a number of reasons to be careful to take this as a discovery of new physics,” says Silvia Galli, a cosmologist at the Paris Institute of Astrophysics.
The authors of both preprints — one posted by the ACT team, and the other by an independent group — admit that the data are not yet strong enough to detect early dark energy with high confidence. But they say that further observations from the ACT and another observatory, the South Pole Telescope in Antarctica, could provide a more stringent test soon. “If this really is true — if the early Universe really did feature early dark energy — then we should see a strong signal,” says Colin Hill, a co-author of the ACT team’s paper1 who is a cosmologist at Columbia University in New York City.
Both the ACT and the South Pole Telescope are designed to map the cosmic microwave background (CMB), primordial radiation sometimes described as the afterglow of the Big Bang. The CMB is one of the pillars of cosmologists’ understanding of the Universe. By mapping subtle variations in the CMB across the sky, researchers have found compelling evidence for the ‘standard model of cosmology’. This model describes the evolution of a Universe containing three primary ingredients: dark energy; the equally mysterious dark matter, which is the primary cause of the formation of galaxies; and ordinary matter, which accounts for less than 5% of the Universe’s total mass and energy.
Current state-of-the-art CMB maps were provided by the European Space Agency’s Planck mission, which was active between 2009 and 2013. Calculations based on Planck data predict — assuming that the standard model of cosmology is correct — exactly how fast the Universe should be expanding now. But for the past decade or so, increasingly accurate measurements of that expansion, based on observations of supernova explosions and other techniques, have found it to be 5–10% faster.
Theorists have suggested a plethora of modifications to the standard model that could explain this difference. Two years ago, cosmologist Marc Kamionkowski at Johns Hopkins University in Baltimore, Maryland, and his collaborators suggested an extra ingredient for the standard model. Their ‘early dark energy’ — which made more precise an idea that they and other teams had been working on for several years — would be a sort of fluid that permeated the Universe before withering away within a few hundred thousand years of the Big Bang. “It’s not a compelling argument, but it’s the only model we can get to work,” says Kamionkowski.
Early dark energy would not have been strong enough to cause an accelerated expansion, as ‘ordinary’ dark energy is currently doing. But it would have caused the plasma that emerged from the Big Bang to cool down faster than it would have otherwise. This would affect how CMB data should be interpreted — especially when it comes to measurements of the age of the Universe and its rate of expansion that are based on how far sound waves were able to travel in the plasma before it cooled into gas. Planck and similar observatories use features that were left in the sky after this transition to make such calculations.
The two latest studies find that the ACT’s map of the CMB’s polarization fits better with a model including early dark energy than with the standard one. Interpreting the CMB on the basis of the early dark energy model and ACT data would mean that the Universe is now 12.4 billion years old, about 11% younger than the 13.8 billion years calculated using the standard model, says Hill. Correspondingly, the current expansion would be about 5% faster than the standard model predicts — closer to what astronomers calculate today.
Hill says that he was previously sceptical about early dark energy, and that his team’s findings surprised him. Vivian Poulin, an astrophysicist at the University of Montpellier in France and a co-author of the second study based on ACT data, says it was reassuring that his team’s analysis agreed with the ACT team’s own. “The lead authors are very, very hard-nosed, conservative people, who really understand the data and the measurements,” Kamionkowski says.
But Galli warns that the ACT data seem to be inconsistent with calculations by the Planck team, which she was part of. And although the ACT’s polarization data might favour early dark energy, it is unclear whether its other major set of data — its map of CMB temperatures — shows such a preference. For these reasons, she adds, it will be crucial to cross-check the results using the South Pole Telescope, an experiment she is part of.
Wendy Freedman, an astronomer at the University of Chicago in Illinois who has contributed to some of the most precise measurements of cosmic expansion, says that the ACT-based results are interesting, if preliminary. “It is important to pursue different models” and compare them with the standard one, she says.
See Davide Castelvecchi's article with references and images at https://www.nature.com/articles/d41586-021-02531-5
12. Chicxulub crater Anniversary
This month marks the 30th anniversary of the publication of the article identifying the Chicxulub crater as the one resulting from the impact of a minor body that wiped out the dinosaurs and many other species from Earth. Ten years before, in 1980, L. W. Álvarez et al. had found anomalously high concentrations of iridium in the sedimentary layer corresponding to the CretaceousPaleogene boundary (the socalled
KPg boundary) dated 66 million years ago. They attributed such large concentrations of iridium to the impact of an extraterrestrial body of a size that they estimated to be of 10 km ± 4 km. However, no crater had been found at that time that corresponded to such a large possible impact. It took roughly a decade to locate the crater. In September 1991, A.R. Hildebrand et al. published the definitive article about this global search for the impact crater. In their publication, they provided the geological clues in terms of gravity and magnetic data, stratigraphy, petrology and morphology to justify their inferences on the age and origin of the causing impact object. With all that in hand, they concluded that the resulting ~180 km crater, hidden below the surface and sea of the Yucatán Peninsula, was the perfect candidate for the long search that the international geology community had undertaken to find the KPg boundary culprit.
--- From the European Space Agency’s NEO Coordination Centre September Newsletter.
13. Gifford-Eiby Lecture Fund
The RASNZ administers the Gifford-Eiby Memorial Lectureship Fund to
assist Affiliated Societies with travel costs of getting a lecturer
or instructor to their meetings. Details are in RASNZ By-Laws Section
H and at http://rasnz.org.nz/rasnz/ge-fund
The application form is at
http://rasnz.org.nz/Downloadable/RASNZ/GE_Application2019.pdf
14. How to Join the RASNZ
RASNZ membership is open to all individuals with an interest in
astronomy in New Zealand. Information about the society and its
objects can be found at
http://rasnz.org.nz/rasnz/membership-benefits
A membership form can be either obtained from treasurer@rasnz.co.nz or
by completing the online application form found at
http://rasnz.org.nz/rasnz/membership-application
Basic membership for the 2021 year starts at $40 for an ordinary
member, which includes an electronic subscription to our journal
'Southern Stars'.
15. Quote
The United Nations (UN) has not explicitly invited science leaders to join the 76th session of the UN General Assembly, which starts this week. Given the UN’s recognition of the part that science plays in achieving the sustainable development goals, it is a puzzling decision. The General Assembly is the UN’s means of bringing together world leaders, civil-society champions, young people and global businesses around the need to solve common problems. If we are serious about science advice, science should not be confined to satellite or domain-specific events. The UN needs to take the next step and place the science agenda front and centre on the UN General Assembly agenda. Meanwhile, this year science will be discussed in its own Science Summit, held in parallel to the main event. Let us hope next year it will be different.
-- Magdalena Skipper, Nature editor-in-chief
Alan Gilmore Phone: 03 680 6817
P.O. Box 57 alan.gilmore@canterbury.ac.nz
Lake Tekapo 7945
New Zealand
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December Celestial Calendar by Dave Mitsky
September 2021 Celestial Calendar by Dave Mitsky
All times, unless otherwise noted, are UT (subtract four hours and, when appropriate, one calendar day for EDT)
9/1 The equation of time, which yields the difference between mean solar time and apparent solar time, equals 0 at 8:00; the Moon is 1.4 degrees north of the bright open cluster M35 in Gemini at 11:00
9/2 The Moon is 6.6 degrees south of the first-magnitude star Castor (Alpha Geminorum) at 23:00
9/3 The Moon is 3.0 degrees south of the first-magnitude star Pollux (Beta Geminorum) at 5:00
9/4 The Moon is 3.1 degrees north-northeast of the bright open cluster M44 (the Beehive Cluster or Praesepe) in Cancer at 7:00
9/5 Venus is 1.6 degrees north-northeast of the first-magnitude star Spica (Alpha Virginis) at 21:00
9/6 The Moon is 4.5 degrees north-northeast of the first-magnitude star Regulus (Alpha Leonis) at 0:00; Mercury is at aphelion (0.4667 astronomical units from the Sun) at 0:00
9/7 New Moon (lunation 1221) occurs at 0:51; the Moon is 3.8 degrees north-northeast of Mars at 20:00
9/9 The Moon is 5.9 degrees north-northeast of Mercury at 2:00; the Moon is 5.3 degrees north-northeast of Spica at 22:00
9/10 The Moon is 3.7 degrees north-northeast of Venus at 6:00
9/11 Asteroid 2 Pallas (magnitude +7.8 ) is at opposition in Pisces at 2:00; the Moon is at perigee, subtending 32' 26" from a distance of 368,462 kilometers (228,951 miles), at 10:03
9/12 The Moon is at descending node (longitude 244.7 degrees) at 17:00
9/13 The Moon is 4.1 degrees north-northeast of the first-magnitude star Antares (Alpha Scorpii) at 3:00; the Lunar X, also known as the Werner or Purbach Cross, an X-shaped clair-obscur illumination effect involving various ridges and crater rims located between the craters La Caille, Blanchinus, and Purbach, is predicted to be visible at 22:08; First Quarter Moon occurs at 20:39
9/14 Mercury is at greatest eastern elongation (27 degrees) at 4:00; Neptune (magnitude +7.8, angular size 2.3") is at opposition at 9:00
9/16 The Sun enters Virgo (ecliptic longitude 174.2 degrees) at 20:00
9/17 The Moon is 3.7 degrees southeast of Saturn at 5:00; Mars crosses south of the celestial equator at 20:00
9/18 The Moon 3.8 degrees southeast of Jupiter at 10:00
9/20 The Moon is 3.7 degrees southeast of Neptune at 13:00; Full Moon (known as the Barley, Corn, or Fruit Moon, and this year's Harvest Moon) occurs at 23:54
9/21 Mercury is 1.4 degrees south-southwest of Spica at 15:00
9/22 The Sun's longitude is 180 degrees at 19:22; the northern hemisphere autumnal equinox occurs at 19:22
9/24 The Moon is 1.3 degrees southeast of Uranus at 18:00
9/26 The Moon is 4.3 degrees southeast of the bright open cluster M45 (the Pleiades or Subaru) in Taurus at 3:00; Mercury is at its southernmost latitude from the ecliptic plane (-7.0 degrees) at 6:00; the Moon is at the ascending node (longitude 63.4 degrees) at 8:00; the Moon is 6.0 degrees north of the first-magnitude star Aldebaran (Alpha Tauri) at 21:00; the Moon is at apogee, subtending 29' 32" from a distance of 404,640 kilometers (251,432 miles), at 21:44
9/27 Mercury is stationary, with retrograde (westward) motion to begin, at 4:00
9/28 The Moon is 1.6 degrees north of M35 at 19:00
9/29 Last Quarter Moon occurs at 1:57; the Curtiss Cross, an X-shaped illumination effect located between the craters Parry and Gambart, is predicted to be visible at 21:48
9/30 The Moon is 6.3 degrees south of Castor at 8:00; the Moon is 2.8 degrees south of Pollux at 13:00
Jean-Dominique Maraldi discovered the globular cluster M15 on September 7, 1746. On September 11, 1746, Jean-Dominique Maraldi discovered the globular cluster M2. Nicolas-Louis de Lacaille discovered NGC 104 (47 Tucanae), the second largest and brightest globular cluster, on September 14th, 1751. William Herschel discovered the barred spiral galaxy NGC 7753 on September 12, 1784. William Herschel discovered the Saturnian satellite Mimas on September 17, 1789. Comet C/1793 S2 (Messier) was discovered by Charles Messier on September 27th, 1793. Karl Harding discovered asteroid 3 Juno on September 1, 1804. Neptune was discovered by Johann Gottfried Galle on September 23, 1846, using Urbain Le Verrier’s calculations of its position. On September 19, 1848, William Bond discovered Saturn’s fourteenth-magnitude satellite Hyperion, the first irregular moon to be discovered. On September 13, 1850, John Russell Hind discovered the asteroid 12 Victoria. E. E. Barnard discovered Jupiter’s fifth satellite, fourteenth-magnitude Amalthea, using the 36-inch refractor at the Lick Observatory, on September 9, 1892.
Only very minor meteor showers occur this month.
Information on passes of the ISS, the USAF’s X-37B, the HST, Starlink, and other satellites can be found at http://www.heavens-above.com/
The Moon is 23.3 days old, is illuminated 35.7%, subtends 29.6 arc minutes, and is located in Taurus on September 1st at 00:00 UT. The Moon is at its greatest northern declination on September 2nd (+25.9 degrees) and on September 29th (+26.0 degrees) and its greatest southern declination on September 15th (-26.0 degrees). Longitudinal libration is at a maximum of +5.2 degrees on September 20th and a minimum of -5.3 degrees on September 5th. Latitudinal libration is at a maximum of +6.6 degrees on September 19th and a minimum of -6.5 degrees on September 6th. Favorable librations for the following lunar features occur on the indicated dates: Crater Schickard on September 3rd, Lacus Spei on September 14th, Mare Humboldtianum on September 18th, and Crater Graff on September 30th. The Moon is at perigee (at a distance of distance 57.77 Earth-radii) on September 11th and at apogee (at a distance 63.44 Earth-radii) on September 26th. New Moon (i.e., the dark of the Moon) occurs on September 7th. Full Moon occurs on September 20th. Browse http://www.lunar-occultations.com/iota/iotandx.htm for information on lunar occultation events. Visit https://saberdoesthestars.wordpress.com/.../saber-does.../ for tips on spotting extreme crescent Moons and https://curtrenz.com/moon.html for Full Moon and other lunar data. Browse https://skyandtelescope.org/wp-content/uploads/MoonMap.pdf and https://nightsky.jpl.nasa.gov/docs/ObserveMoon.pdf for simple lunar maps. Click on http://astrostrona.pl/moon-map for an excellent online lunar map. Visit http://www.ap-i.net/avl/en/start to download the free Virtual Moon Atlas. Consult http://time.unitarium.com/moon/where.html for current information on the Moon and https://www.fourmilab.ch/earthview/lunarform/lunarform.html for information on various lunar features. See https://svs.gsfc.nasa.gov/4874 for a lunar phase and libration calculator and https://quickmap.lroc.asu.edu/?extent=-90,-25.2362636,90,25.2362636&proj=10&layers=NrBsFYBoAZIRnpEoAsjYIHYFcA2vIBvAXwF1SizSg for the Lunar Reconnaissance Orbiter Camera (LROC) Quickmap. Click on https://www.calendar-12.com/moon_calendar/2021/september for a lunar phase calendar for this month. Times and dates for the lunar crater light rays predicted to occur this month are available at http://www.lunar-occultations.com/rlo/rays/rays.htm
The zodiacal light, or the false dawn, is visible about two hours before sunrise from a dark site for two weeks beginning on September 5th. It can be seen in Leo, Cancer, Gemini, and Taurus. Articles on the zodiacal light appear at http://www.atoptics.co.uk/highsky/zod1.htm and http://oneminuteastronomer.com/6645/zodiacal-light/
The Sun is located in Leo on September 1st. It enters Virgo on September 16th. The Sun crosses the celestial equator from north to south at 19:22 UT on September 22nd, the date of the autumnal equinox.
Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on September 1st: Mercury (magnitude -0.1, 5.9", 74% illuminated, 1.15 a.u., Virgo), Venus (magnitude -4.0., 15.1", 73% illuminated, 1.11 a.u., Virgo), Mars (magnitude +1.8, 3.6", 100% illuminated, 2.63 a.u., Leo), Jupiter (magnitude -2.9, 48.9", 100% illuminated, 4.03 a.u., Capricornus), Saturn (magnitude +0.3, 18.3", 100% illuminated, 9.06 a.u., Capricornus), Uranus (magnitude +5.7, 3.7", 100% illuminated, 19.09 a.u. on September 16th, Aries), Neptune (magnitude +7.8, 2.4", 100% illuminated, 28.92 a.u. on September 16th, Aquarius), and Pluto (magnitude +14.3, 0.1", 100% illuminated, 33.62 a.u. on September 16th, Sagittarius).
During the month of September, Mercury and Venus are located in the west, Jupiter and Saturn in the southeast, and Neptune in the east during the evening. At midnight, Jupiter and Neptune can be found in the south, Saturn in the southwest, and Uranus in the east. Uranus is in the southwest and Neptune is in the west in the morning sky.
Mercury continues a poor evening apparition for mid-northern hemisphere observers this month. The speediest planet achieves aphelion on September 6th and greatest eastern elongation on September 14th. A very thin waxing crescent Moon passes almost six degrees north of Mercury on the evening of September 8th. On September 9th, Mercury lies 13 degrees to the lower right of the waxing crescent Moon and just over three degrees above the western horizon. Mercury passes less than two degrees northeast of Spica on September 21st.
Venus sets about 30 minutes after Mercury. By month's end, Venus sets about two hours after the Sun. The brightest planet increases in brightness from magnitude -4.0 to magnitude -4.2, increases in apparent size from 15.1 arc second to 18.6 arc seconds, and decreases in illumination from 73% to 63%. Venus passes less than two degrees north of Spica on September 5th. The three-day old waxing crescent Moon passes four degrees north of Venus on September 9th.
Mars is too close to the Sun to observe this month.
Jupiter decreases in brightness from magnitude -2.9 to magnitude -2.7 and shrinks in angular diameter from 48.9 arc seconds to 46.4 arc seconds over the course of September. Jupiter passes 1.5 degrees north of the third-magnitude star Deneb Algedi on September 12th. The waxing gibbous Moon passes four degrees south of the Jupiter on September 18th. Transits by Europa, Europa's shadow, Ganymede, and eventually Ganymede's shadow take place beginning at 8:59 p.m. EDT on September 5th. This event occurs again on the night of September 12th/13th starting at 8:26 p.m. EDT. Io and Ganymede are less than six arc minutes apart at 10:20 p.m. EDT that night. Information on Great Red Spot transit times and Galilean satellite events is available on pages 50 and 51 of the September 2021 issue of Sky & Telescope and online at http://www.skyandtelescope.com/.../interactive-sky.../ and https://www.projectpluto.com/jeve_grs.htm
During September, Saturn fades from magnitude +0.3 to magnitude +0.5 and shrinks in apparent size from 18.3 arc seconds to 17.7 arc seconds. Its rings are tilted 19 degrees with respect to the Earth. The waxing gibbous Moon passes four degrees south of the Ringed Planet on the night of September 16th/17th. Titan, Saturn’s largest and brightest satellite, shines at magnitude +8.5. It's due north of the planet on September 3th and September 19th and due south of it on September 11th and September 27th. An eighth-magnitude field star joins Titan to Saturn's southwest on September 12th. The star lies to the southeast of the planet on September 13th. Saturn’s peculiar satellite Iapetus glows at eleventh magnitude on September 1st as it is passes 1.5 arc minutes southwest of the planet. By the time Iapetus reaches western elongation nine arc minutes due west of Saturn on September 20th, it will have brightened to about tenth magnitude. For further information on Saturn’s satellites, browse http://www.skyandtelescope.com/.../interactive-sky.../
Uranus lies halfway between the fifth-magnitude stars Omicron and Sigma Arietis at the beginning of the month. By the final day of September, it is located within 25 arc minutes of Omicron. The waning gibbous Moon passes about one degree southeast of Uranus on September 24th. Visit http://www.nakedeyeplanets.com/uranus.htm for a finder chart. Five of the brightest Uranian satellites (Miranda, Ariel, Umbriel, Titania, and Oberon) can be located using the Sky & Telescope interactive observing tool at https://skyandtelescope.org/.../the-elusive-moons-ofuranus/
Neptune is located almost five degrees east of the fourth-magnitude star Phi Aquarii as September begins. The ice giant planet lies less than four degrees east of the star at the end of the month. It passes within 1.5 arc minutes of a sixth-magnitude star on September 23rd. Neptune subtends 2.3 arc seconds, shines at magnitude +7.8, and lies at a distance of 4.0 light hours when it reaches opposition on September 14th. The Full Moon passes less than four degrees southeast of Neptune on September 20th. See http://www.nakedeyeplanets.com/neptune.htm for an online finder chart. An article on Neptune complete with a finder chart appears on pages 48 and 49 of the September 2021 issue of Sky & Telescope. Triton, Neptune's brightest satellite, can be located using the Sky & Telescope interactive observing tool at https://skyandtelescope.org/.../sky-telescopes-triton.../
The dwarf planet Pluto is located near the Teaspoon asterism in northeastern Sagittarius at a declination of nearly -23.0 degrees. Finder charts can be found at pages 48 and 49 of the July 2021 issue of Sky & Telescope and on page 243 of the RASC Observer’s Handbook 2021.
For more on the planets and how to locate them, see http://www.nakedeyeplanets.com/
The Distance, Brightness, and Apparent Size of Planets graphic at https://www.timeanddate.com/astronomy/planets/distance displays the apparent and comparative sizes of the planets, along with their magnitudes and distances, on a given date and time.
Comet C/2020 T2 (Palomar) is predicted to be the brightest comet visible this month. It heads to the southeast through Virgo and into Libra. The periodic comet 15P/Finlay passes northeastward through Taurus and into Gemini. Comet 67P/Churyumov-Gerasimenko is a rather faint target as it travels northeastward through Aries and Taurus. This periodic comet orbits the Sun once every 6.5 years between the orbits of Jupiter and Earth. It was visited by the Rosetta spacecraft and the Philae probe seven years ago. Visit http://cometchasing.skyhound.com/ and http://www.aerith.net/comet/future-n.html and https://cobs.si/ for additional information on comets visible this month.
Asteroid 89 Julia shines at ninth-magnitude as it heads northwestward through Aquarius. It passes several degrees north of the globular cluster M2 on September 24th and September 25th. Asteroid 2 Pallas reaches opposition in Pisces on September 11th. A finder chart can be found on page 49 of the September 2021 issue of Sky & Telescope. Other asteroids brighter than magnitude +11.0 reaching opposition this month include 532 Herculina on September 19th and 980 Anacostia on September 30th. On the morning of September 17th, the dwarf planet/asteroid 1 Ceres passes just four arc minutes south of the fifth-magnitude star Sigma1 Tauri. Data on asteroid occultations taking place this month is available at http://www.asteroidoccultation.com/2021_09_si.htm and http://www.poyntsource.com/New/Global.htm
A wealth of current information on solar system celestial bodies is posted at http://nineplanets.org/ and http://www.curtrenz.com/astronomy.html
Information on the celestial events transpiring each week can be found at https://stardate.org/nightsky and http://astronomy.com/skythisweek and http://www.skyandtelescope.com/observing/sky-at-a-glance/
An online data generator for various astronomical events is available at https://astronomynow.com/almanac/
The famous eclipsing variable star Algol (Beta Persei) is at a minimum, decreasing in brightness from magnitude +2.1 to magnitude +3.4, on September 1st, 4th, 7th, 10th, 13th, 16th, 18th, 21st, 24th, 27th, and 30th. Consult page 50 of the September 2021 issue of Sky & Telescope for the minima times. On the morning of September 8th, Algol shines at minimum brightness (magnitude +3.4) for approximately two hours centered at 2:55 a.m. EDT (6:55 UT). It does the same at 11:44 p.m. EDT (3:44 UT September 13th) on the night of September 12th. For more on Algol, see http://stars.astro.illinois.edu/sow/Algol.html and http://www.solstation.com/stars2/algol3.htm
Free star maps for this month can be downloaded at http://www.skymaps.com/downloads.html and https://www.telescope.com/content.jsp... and www.whatsouttonight.com/
Weather and observing conditions forecasts are available at https://www.cleardarksky.com/csk/index.html
Data on current supernovae can be found at http://www.rochesterastronomy.org/snimages/
Finder charts for the Messier objects and other deep-sky objects are posted at https://freestarcharts.com/messier and https://freestarcharts.com/ngc-ic and https://www.cambridge.org/.../seasonal_skies_july-september
Telrad finder charts for the Messier Catalog are posted at http://www.custerobservatory.org/docs/messier2.pdf and http://www.star-shine.ch/.../messiercharts/messierTelrad.htm
Telrad finder charts for the SAC’s 110 Best of the NGC are available at http://sao64.free.fr/observat.../catalogues/cataloguesac.pdf
Information pertaining to observing some of the more prominent Messier galaxies can be found at http://www.cloudynights.com/.../358295-how-to-locate.../
Freeware sky atlases can be downloaded at http://www.deepskywatch.com/.../Deep-Sky-Hunter-atlas... and https://www.cloudynights.com/.../free-mag-7-star-charts... and https://allans-stuff.com/triatlas/
Author Phil Harrington offers an excellent freeware planetarium program for binocular observers known as TUBA (Touring the Universe through Binoculars Atlas), which also includes information on purchasing binoculars, at http://www.philharrington.net/tuba.htm
Stellarium and Cartes du Ciel are two excellent freeware planetarium programs that are available at http://stellarium.org/ and https://www.ap-i.net/skychart/en/start
Deep-sky object list generators can be found at www.virtualcolony.com/sac/ and https://telescopius.com/?fromdsobrowser and www.tonightssky.com/MainPage.php
Eighty binary and multiple stars for September: 12 Aquarii, Struve 2809, Struve 2838 (Aquarius); Alpha Capricorni, Sigma Capricorni, Nu Capricorni, Beta Capricorni, Pi Capricorni, Rho Capricorni, Omicron Capricorni, h2973, h2975, Struve 2699, h2995, 24 Capricorni, Xi Capricorni, Epsilon Capricorni, 41 Capricorni, h3065 (Capricornus); Kappa Cephei, Struve 2751, Beta Cephei, Struve 2816, Struve 2819, Struve 2836, Otto Struve 451, Struve 2840, Struve 2873 (Cepheus); Otto Struve 394, 26 Cygni, h1470, h1471, Omicron Cygni, Struve 2657, 29 Cygni, 49 Cygni, 52 Cygni, 59 Cygni, 60 Cygni, 61 Cygni, Struve 2762 (Cygnus); Struve 2665, Struve 2673, Struve 2679, Kappa Delphini, Struve 2715, Struve 2718, Struve 2721, Struve 2722, Struve 2725 (in the same field as Gamma Delphini), Gamma Delphini, 13 Delphini, Struve 2730, 16 Delphini, Struve 2735, Struve 2736, Struve 2738 (Delphinus); 65 Draconis, Struve 2640 (Draco); Epsilon Equulei, Lambda Equulei, Struve 2765, Struve 2786, Struve 2793 (Equuleus); 1 Pegasi, Struve 2797, h1647, Struve 2804, Struve 3112, 3 Pegasi, 4 Pegasi, Kappa Pegasi, h947, Struve 2841, Struve 2848 (Pegasus); h1462, Struve 2653, Burnham 441, Struve 2655, Struve 2769 (Vulpecula)
Notable carbon star for September: LW Cygni
Fifty deep-sky objects for September: M2, M72, M73, NGC 7009 (Aquarius); M30, NGC 6903, NGC 6907 (Capricornus); B150, B169, B170, IC 1396, NGC 6939, NGC 6946, NGC 6951, NGC 7023, NGC 7160, NGC 7142 (Cepheus); B343, B361, Ba6, Be87, Cr 421, Do9, IC 4996, M29, M39, NGC 6866, NGC 6871, NGC 6888, NGC 6894, NGC 6910, NGC 6960, NGC 6992, NGC 6994, NGC 6995, NGC 7000, NGC 7008, NGC 7026, NGC 7027, NGC 7039, NGC 7048, NGC 7063, NGC 7086 (Cygnus); NGC 6891, NGC 6905, NGC 6934, NGC 7006 (Delphinus); NGC 7015 (Equuleus); M15 (Pegasus); NGC 6940 (Vulpecula)
Top ten binocular deep-sky objects for September: IC 1396, LDN 906, M2, M15, M29, M30, M39, NGC 6939, NGC 6871, NGC 7000
Top ten deep-sky objects for September: IC 1396, M2, M15, M30, NGC 6888, NGC 6946, NGC 6960, NGC 6992, NGC 7000, NGC 7009
Challenge deep-sky object for September: Abell 78 (Cygnus)
The objects listed above are located between 20:00 and 22:00 hours of right ascension.
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Minor Planet Occultation Updates:
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Further links and discussion can be found at the groups/links below
Astronomy in New Zealand - Groups.io
https://groups.io/g/AstronomyNZ
Astronomy in New Zealand - Facebook
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Google Group
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Astronomy in Wellington
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Blogger Posts
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Twitter
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Reddit
https://www.reddit.com/user/Edwin_Rod_NZ
Quaroa
https://www.quora.com/q/astronomyinnewzealand
Groups.io
Astronomy in New Zealand
https://groups.io/g/AstronomyNZ
AstronomyNZ@groups.io
Wellington Astronomers
https://groups.io/g/WellingtonAstronomers
WellingtonAstronomers@groups.io
AucklandAstronomers
https://groups.io/g/AucklandAstronomers
AucklandAstronomers@groups.io
North Island Astronomers
https://groups.io/g/NorthIslandAstronomers
NorthIslandAstronomers@groups.io
South Island Astronomers
https://groups.io/g/SouthIslandAstronomers
SouthIslandAstronomers@groups.io
NZAstrochat
https://groups.io/g/NZAstrochat
NZAstrochat@groups.io
NZ Photographers And Observers
https://groups.io/g/NZPhotographers
NZPhotographers@groups.io
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Please note:
My standard caveat that these are the views of a learned amateur, not a professional in the sector, applies as always.
The above post/email/update represents my own words, views, research and opinions, unless stated otherwise the above work
represents my own writing. I’ll give credit or thanks if I have used or represented other people’s words and/or opinions.
The links and references listed below represent the work and research of the respective author’s.
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