RASNZ_20_07_2019
Royal Astronomical Society of New Zealand
eNewsletter: No. 223, 20 July 2019 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. Apollo 11's 50th Anniversary and Future Plans
2. Conference Honours
3. The Solar System in August
4. Stargazers Getaway August 30-September 1
5. 2019 AAS Astrophotography Competition
6. Variable Star News
7. Joan Marie Galat in NZ
8. Space Weather Section Director Sought
9. Secretary for National Astronomical Society
10. Astro-tourism Centre Opened in Tekapo
11. Another Earth-Impactor Tracked
12. Saturn's Rings from Cassini's Close-ups
13. Did a Nearby Supernova Lead to Us?
14. How to Join the RASNZ
15. Gifford-Eiby Lecture Fund
16. Quote
1. Apollo 11's 50th Anniversary and Future Plans
It's the 50th anniversary of the Apollo 11 moon landing but nobody has been back since the end of the Apollo programme. Now everyone, it seems, wants to go the moon.
In January, Chang’e-4, a Chinese robotic spacecraft including a small rover, became the first ever to land on the far side of the moon. India is aiming to launch Chandrayaan-2 this month, its first attempt to reach the lunar surface. Even a small Israeli non-profit, SpaceIL, tried to send a small robotic lander there this year, but it crashed.
In the coming decades, boots worn by visitors from these and other nations could add their prints to the lunar dust. China is taking a slow and steady approach, and foresees its astronauts’ first arrival about a quarter of a century in the future. The European Space Agency has put out a concept of an international “moon village” envisioned for sometime around 2050. Russia has also described plans for sending astronauts to the moon by 2030, at last, although many doubt it can afford the cost.
In the United States, which sent 24 astronauts toward the moon from 1968 to 1972, priorities shift with the whims of Congress and presidents. But NASA in February was suddenly pushed to pick up its pace when Vice President Mike Pence announced the goal of putting Americans on the moon again by 2024, four years ahead of the previous schedule.
“NASA is highly motivated,” Jim Bridenstine, the former Oklahoma congressman and Navy pilot picked by President Trump to be the agency’s administrator, said in an interview. “We now have a very clear direction.”
For India, reaching the moon would highlight its technological advances. China would establish itself as a world power off planet. For the United States and NASA, the moon is now an obvious stop along the way to Mars.
The fascination with Earth’s celestial companion is not limited to nation-states. A bevy of companies has lined up in hopes of winning NASA contracts to deliver experiments and instruments to the moon. Blue Origin, the rocket company started by Jeff Bezos, founder and chief executive of Amazon, is developing a large lander that it hopes to sell to NASA for taking cargo — and astronauts — to the moon’s surface.
For three decades after the end of the Apollo program, few thought much about the moon. The United States had beaten the Soviet Union in the moon race. After Apollo 17, the last visit by NASA astronauts in 1972, the Soviets sent a few more robotic spacecraft to the moon, but they soon also lost interest in further exploration there.
NASA in those years turned its attention to building space shuttles and then the International Space Station. Its robotic explorers headed farther out, exploring Mars more intensely, as well as the asteroid belt and the solar system’s outer worlds.
-- The first paragraphs of a New York Times article by Kenneth Chang
on July 12. See the full article with images at
https://www.nytimes.com/2019/07/12/science/nasa-moon-apollo-artemis.html
Fred Watson has an introduction to the Moon at
https://www.abc.net.au/news/2019-07-16/pocket-guide-to-the-moon/11260558
2. Conference Honours
Two other awards made at the May Conference that were omitted from previous Newsletters:
Kyra Xavia of Dunedin received the Earth and Sky ‘Bright Star’ Award. Kyra has been extremely active in the promotion of astronomy and in the work of preserving the night sky from the effects of light pollution.
Gordon Hudson of Porirua received the President’s Service Award. Gordon was RASNZ President between 2012-14. He served as Secretary during this current term. Gordon has actively promoted astronomy and star parties since the 1980s and is an active observer/contributor.
-- From Keeping in Touch #33.
3. The Solar System in August
Dates and times shown are NZST (UT + 12 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.
THE SUN and PLANETS in AUGUST, Rise & Set, Magnitude & Constellation
August 1 NZST August 31 NZST
Mag Cons Rise Set Mag Cons Rise Set
SUN -26.7 Cnc 7.27am 5.27pm -26.7 Leo 6.46am 5.57pm
Merc 1.9 Gem 6.21am 4.19pm -1.8 Leo 6.46am 5.33pm
Venus -3.9 Cnc 7.21am 5.05pm -3.9 Leo 7.05am 6.17pm
Mars 1.8 Leo 8.04am 6.17pm .1.7 Leo 6.55am 5.57pm
Jup -2.4 Oph 1.07pm 4.16am -2.2 Oph 11.10am 2.08am
Sat 0.3 Sgr 3.20pm 6.18am 0.3 Sgr 1.15pm 4.15am
Uran 5.8 Ari 12.41am 11.15am 5.7 Ari 10.42pm 9.17am
Nep 7.8 Aqr 8.35pm 9.23am 7.8 Aqr 6.34pm 7.24am
Pluto 14.4 Sgr 3.46pm 6.43am 14.4 Sgr 1.45pm 4.43am
August 1 NZST August 31 NZST
Twilights morning evening morning evening
Civil: start 7.00am, end 5.55pm start 6.21am, end 6.23pm
Nautical: start 6.27am, end 6.28pm start 5.49am, end 6.55pm
Astro: start 5.54am, end 7.01pm start 5.17am, end 7.27pm
AUGUST PHASES OF THE MOON, times NZST (& UT)
New moon: Aug 1 at 3.12pm (03:12 UT)
First quarter: Aug 8 at 5.31am (Aug 7, 17:31 UT).
Full Moon: Aug 16 at 12.29am (Aug 15, 12:29 UT)
Last quarter Aug 24 at 2.56am (Aug 23, 14:56 UT)
New Moon: Aug 30 at 10:37pm (10:37 UT)
PLANETS in August.
MERCURY, VENUS and MARS: during the last 8 days of August the three terrestrial planets are all in Leo - with the Sun (see table above). Not surprisingly, the three planets are unobservable during August. On the 30th they are joined by the New Moon with all three planets at conjunction with our satellite during the 24 hours. Again, an unobservable event.
Remembering that this is as viewed from the Earth, it means that there is effectively a line-up of all 4 inner planets and Sun.
JUPITER and SATURN meanwhile are visible much of the night rising well before the time of Sunset and setting after midnight. Jupiter is stationary on the 11th when it will be just under 7° from Antares.
This month's lunar occultation of Saturn is on the 12th. It is visible from most of the North Island but is a miss from the South Island. The southern limit grazing occultation of Saturn occurs along a west to east band which includes Carterton and Masterton. The extreme outer edge is at Greytown where Saturn only just touches the moon. Further north increasing amounts of Saturn are hidden until the latitude of Otaki from where Saturn is, briefly, fully obscured The duration of the occultation increases the further north one goes, more than an hour at North Cape.
Predictions of times of the occultation for a number of places in the North Island and Eastern Australia are available on the Occultation Section web site.
PLUTO is close behind Saturn, rising and setting half an hour later.
URANUS remains a morning object in Aries.
NEPTUNE, is in Aquarius. By the end of August it is in the sky most of the night.
BRIGHTEST ASTEROIDS in AUGUST, magnitude, constellation, time of transit
AUGUST 1 NZDT AUGUST 31 NZST
Mag Cons transit Mag Cons transit
(1) Ceres 8.4 Lib 7.38am 8.9 Sco 5.59pm
(4) Vesta 8.1 Ari 6.54am 7.7 Tau 5.24am
(15) Eunomia 8.5 Aqr 1.12am 8.5 Aqr 10.45pm
CERES moves into Scorpius on the 1st. It passes between the second magnitude stars delta and beta Sco midmonth and ends August just over 5° from Antares and 9° from Jupiter.
VESTA is in the morning sky, rising at 1.30 am on the 1st and at midnight on the 31st. It moves into Taurus on the 11th.
EUNOMIA is at opposition on August 12 with a magnitude 8.2. It will then be in the sky most of the night.
-- Brian Loader
4. Stargazers Getaway August 30 - September 1
The North Otago Astronomical Society Inc, would like to invite you to Stargazers Getaway 2019, over the weekend of, Friday August 30th to Sunday September 1st at Camp Iona in Herbert.
This is the second year back for our iconic Stargazers Getaway, building on last year's camp, the first in over 10 years!
With expressions for attendees already coming in, this year is promising to be bigger and better!!
Children under 5 are free
Students 5-17 - $20 p/night, $35 for both
Adults +18 - $35 p/night, $60 for both
Day visits for talks - $5 p/day
Interested people who would like to either attend, speak or present a poster paper are asked to email the Stargazers Getaway Co-ordinator, Damien McNamara, as numbers are limited at :- solaur.science@gmail.com
5. 2019 AAS Astrophotography Competition
Calling all Astrophotographers: get your entries in for the 2019 New Zealand Astrophotography competition before the competition cut-off date of September 30. Winners will be announced at the Auckland Astronomical Society's annual Burbidge dinner.
This year's judge is the "Bad Astronomer" Phil Plait, American astronomer, sceptic, writer and popular science blogger. Phil is best known for debunking misconceptions in astronomy but is also a well-known astrophotography enthusiast.
Prizes are one year subscriptions to Australian Sky & Telescope and a $300 Astronz gift voucher. As well the Auckland Astronomical Society will provide a cash prize for each category winner.
For categories, prize details, competition rules and entry forms see the homepage of the Auckland Astronomical Society website
https://www.astronomy.org.nz/new/public/default.aspx
-- Abridged from a note to the nzastronomers group by Jonathan Green.
6. Variable Star News
False Flare
A flurry of posts was spawned on the Variable Stars South (VSS) Google discussion group starting in June. An observation was reported by Marcos da Silva of a light outburst of the 4th magnitude star Gamma Ophiuchi. The brightening was about 2 magnitudes. As this was not a known variable star a number of questions were asked and more information was provided over several posts. The observation was a short video over quite a large area of sky (60 degrees across) taken with a meteor camera, part of the Brazilian Meteor Observation Network (BRAMON). The video was taken in South America and the time of day was soon after nightfall; the video was also posted. It was eventually proposed that the phenomenon was probably due to a flash from an earth-orbiting satellite coincidentally at the same position as the star. A web-site that publishes predictions of flash events had a couple of occurrences near Gamma Oph at the time of observation. It is intriguing that the equipment launched into earth orbit can unknowingly interfere with our observations of stellar objects far away. Another explanation proposed, in this case celestial, was an incoming meteor aligned head-on with the camera. The video is available on the VSS website under “News Items” or using the following link: https://www.variablestarssouth.org/unusual-brightening-of-gamma-ophiuchi/
The comments on the flash event were mixed in with a lot of discussion of basic photometric procedures such as making and filing darks and flats. It is proposed that an updated guide to procedures for photometric systems and software will be produced, distilling the best methodologies from this discussion.
AAVSO
Three more CHOICE education courses are being offered in the remainder of the 2019 year. Notable is Exoplanet Observing, November 4 - December 6. For the full list refer to the AAVSO web-site or the July monthly Circular.
VSS Symposium in 2000
The Variable Stars South Symposium 6 (VSS S6) will be held on Friday April 10th, the first day of the 29th National Australian Convention of Amateur Astronomers, Easter weekend 2020, 10-13 April. The NACAA XXIX event will be held at Parkes, a NSW Regional Town, and hosted by the Central West Astronomical Society. Parkes is the site of the Parkes Radio Telescope, the famous 64 m steerable dish which has been operating since 1961. The website for the NACCA event is https://nacaa.org.au/2020/about. We will advise details of the VSS Symposium when they are posted on the VSS website.
Star Alert
The variable V854 Centauri appears to have commenced a decline. This star is a R Coronae Borealis (RCB) type star; this class of star undergoes large fades in brightness intermittently due to obscuration by dust clouds in the stellar atmosphere. Each event tends to be unique in duration and magnitude decline.
-- Alan Baldwin
7. Joan Marie Galat in NZ
Joan Marie Galat is a Canadian-based international award-winning author whose career began at the age of 12, when she was hired as a newspaper columnist. Now she is the author of more than 20 books, including a Canadian best seller. Joan shares her love of the night sky in her Dot to Dot in the Sky series (Whitecap Books), which partners sky science with the stories early cultures first told to explain their observations. Dark Matters—Nature’s Reaction to Light Pollution (Red Deer Press) offers personal stories, revealing how light at night impacts wildlife. Other titles include Black Holes and Supernovas, The Discovery of Longitude, and an upcoming title: Absolute Expert – Space (National Geographic Kids).
A professional speechwriter, former radio show host, and frequent presenter, Joan has travelled across Canada and from the Arctic Circle to Australia, South Korea, and the USA to deliver presentations promoting science and literacy. In 2016, Joan spoke about the night sky environment at a United Nations event in Seoul. Featured at the Jasper Dark Sky Festival and numerous other night sky events, she presented at the International Dark-Sky Association annual meeting in 2018. When not writing or talking about the night sky, Joan enjoys stiltwalking and can sometimes be seen in costume at Edmonton festivals.
PRESENTATIONS and WORKSHOP
Joan will be touring in New Zealand October 14 – 28, 2019. She is available for adult, family, and student presentations that explore the world through science and story. You can watch Joan’s speaker demo and book trailers, and view book descriptions at www.joangalat.com.
-- Forwarded by John Hearnshaw.
8. Space Weather Section Director Sought
Dear Members,
Following his valuable term of service as Director of the Space Weather Section, Damien McNamara has chosen to step down from that position. Damien has become more involved with the challenges brought by increasing light pollution from new and additional sources. For and on behalf of the Council, I would like to thank Damien for his effort, energy and leadership.
Damien stepped down as Director on 5 May 2019. At this time, Council is inviting any Member of the Society who wishes to be considered for the Directorship of the Space Weather Section to apply. Applications close at 5 p.m. 12 April 2019.
Applications are to be sent by post or email to the Secretary by the above deadline; secretary@rasnz.org.nz.
Applications are to include
1. a statement of interest which sets out the Member's interests in Space Weather, their past experience, their plans for leading the Section and any new initiatives for the Section's members, and
2. the names and contact details of two referees of whom Council can request further information about the applicant. Applications are to be no more than two sides of A4 in length, font size at least 12, font either Times New Roman or Ariel.
Yours,
Nicholas Rattenbury, RASNZ President.
9. Secretary for National Astronomical Society
The Royal New Zealand Astronomical Society (RASNZ) is seeking a suitable person to take on the voluntary role of Secretary. This is an important role within RASNZ. The new appointee will be a key member of RASNZ helping administer and make strategic decisions for RASNZ.
No formal qualifications or prior experience in a similar role are necessary, and, this role does not preclude holders of positions in other astronomical societies. However, knowledge of RASNZ rules
(https://www.rasnz.org.nz/images/articleFiles/Council/Rules2015.pdf), history and operations would be beneficial to performing the duties. Templates created by former holders of this position will be made available. This role can be undertaken entirely from the home office but attendance at the RASNZ Council's AGM held once a year at the RASNZ annual conference is strongly encouraged.
The responsibilities of the Secretary include:
(i) Receive and send physical and electronic correspondence on behalf of the RASNZ, document it and draw appropriate people's attention to the
correspondence;
(ii) Compile the Council's Annual Report and prepare it for approval by the Council in time for publication in the March issue of Southern Stars, and
(iii) Maintain a record of meetings and motions, both physical and electronic.
This offers a great opportunity for someone to contribute to the nationwide support and promotion of astronomy, science education and related research.
Contact: Nick Rattenbury (nicholas.rattenbury@gmail.com)
President - RASNZ
10. Astro-tourism Centre Opened in Tekapo
An $11 million, fully immersive dark sky experience is now open in Tekapo combining Māori astronomy and science.
Dark Sky Project, formerly Earth and Sky, opened the doors to its new 1140sqm building on the Tekapo lakefront on July 1 and is a joint venture between Ngāi Tahu Tourism and co-founders Graeme Murray and Hide Ozawa.
The centre includes the Dark Sky Diner, and will be the departure point for the astro-tourism business' outdoor, evening stargazing experiences.
Mana whenua from Arowhenua, Waihao and Moeraki rūnanga blessed the building named Rehua on Monday while Governor-General of New Zealand, Dame Patsy Reddy, opened the new experience.
Murray said it "has been incredible" to watch the building take shape, especially the moment the large observatory dome was craned on in April.
"Ever since Hide and I stood on the summit of Ōtehīwai (Mt John) looking up at the night sky 15 years ago, it has been our dream to develop a home for astronomy in the heart of the Aoraki Mackenzie International Dark Sky Reserve, so that we could inspire a lifelong understanding and passion for our night skies."
The dome houses the 125-year-old Brashear Telescope, which stands up to nine metres tall and was in storage for five decades before being restored in Fairlie over the past two years. The telescope is now part of the new 45-minute Dark Sky Experience.
The centre will tell the stories of local iwi and runanga's relationship with the night sky, and how it has developed.
It is located at the heart of the Aoraki/Mt Cook Mackenzie International Dark Sky Reserve - the largest dark sky reserve in the world and the only one of its kind in the Southern Hemisphere.
Te Rūnanga o Ngāi Tahu Kaiwhakahaere Lisa Tumahai said the $3m in government funding provided by the Tourism Growth Partnership fund in 2016 was the kick-start the $11 million development needed. "It will further enhance the Ngāi Tahu contribution to regional development and job creation – mō tātou, ā, mō ka uri ā muri ake nei. I truly commend mana whenua and all involved in the creation of an authentic experience that will see our ancestors' stories told to the world."
To ensure the Dark Sky Experience was authentic, Dark Sky Project worked with mana whenua from Arowhenua, Waihao and Moeraki, leading Māori astronomy expert Professor Rangi Mātāmua and the University of Canterbury to bring to life the stories of the universe.
-- From The Timaru Herald of July 2. See the original text with photos at https://www.stuff.co.nz/travel/destinations/nz/113896886/new-star-attraction-opens-in-tekapo-combining-mori-astronomy-and-science
11. Another Earth-Impactor Tracked
On June 22 around 21:26 UT (17:26 local time), a roughly 5-metre object entered the atmosphere over the Caribbean Sea, and exploded at an altitude of about 25 km over the sea surface, releasing an energy roughly equivalent to 3 kilotons of TNT. The explosion was first detected by the geostationary Lightning Mapper (GLM) instrument on board the GOES-16 geostationary satellite.
A couple of days later the NASA JPL team realised that an object appearing on the NEO Confirmation Page as A10eoM1, discovered on the morning of June 22 by the ATLAS survey in Hawaii, could be a good candidate progenitor for the fireball event. This tentative identification allowed the Pan-STARRS team to locate three pre-discovery detections of the object in images obtained by the Pan-STARRS2 telescope a couple of hours before the ATLAS discovery. Adding the corresponding astrometry to the orbit determination confirmed the identification of the object with the fireball event, pinpointing the impact location with a precision of a few hundred km.
The asteroid has now been designated 2019 MO and is the fourth known impactor detected by surveys before impact with our planet.
Past impactors have been 2008 TC3, on 2008 October 7, about 4 metres across, found 20 hours before impact; 2014 AA on 2014 January 2, 2-4 metres across, found about 22 hours before impact; 2018 LA found on 2018 June 2, 2-5 metres across, found 8 hours before impact; and 2019 MO, 4-8 metres across, recorded 13 hours before impact.
For more information see http://neo.ssa.esa.int
-- Copied from the European Space Agency's NEO Coordination Centre Newsletter July 2019. See the above website for the original.
12. Saturn's Rings from Cassini's Close-ups
As NASA's Cassini spacecraft (https://solarsystem.nasa.gov/cassini) dove close to Saturn in its final year, the spacecraft provided intricate detail on the workings of Saturn's complex rings, new analysis shows.
Although the mission ended in 2017, science continues to flow from the data collected. A new paper published on June 13 in Science describes results from four Cassini instruments taking their closest-ever observations of the main rings.
Findings include fine details of features sculpted by masses embedded within the rings. Textures and patterns, from clumpy to straw-like, pop out of the images, raising questions about the interactions that shaped them. New maps reveal how colours, chemistry and temperature change across the rings.
Like a planet under construction inside a disk of protoplanetary material, tiny moons embedded in Saturn's rings (named A through G, in order of their discovery) interact with the particles around them. In that way, the paper provides further evidence that the rings are a window into the astrophysical disk processes that shape our solar system.
The observations also deepen scientists' understanding of the complex Saturn system. Scientists conclude that at the outer edge of the main rings, a series of similar impact-generated streaks in the F ring have the same length and orientation, showing that they were likely caused by a flock of impactors that all struck the ring at the same time. This shows that the ring is shaped by streams of material that orbit Saturn itself rather than, for instance, by cometary debris (moving around the Sun) that happens to crash into the rings.
"These new details of how the moons are sculpting the rings in various ways provide a window into solar system formation, where you also have disks evolving under the influence of masses embedded within them," said lead author and Cassini scientist Matt Tiscareno of the SETI Institute in Mountain View, California.
At the same time, new puzzles have arisen and old mysteries have deepened with the latest research. The close-up ring images brought into focus three distinct textures -- clumpy, smooth and streaky -- and made it clear that these textures occur in belts with sharp boundaries. But why? In many places the belts aren't connected to any ring characteristics that scientists have yet identified.
"This tells us the way the rings look is not just a function of how much material there is," Tiscareno said. "There has to be something different about the characteristics of the particles, perhaps affecting what happens when two ring particles collide and bounce off each other. And we don't yet know what it is."
The data analysed were gathered during the Ring Grazing Orbits (December 2016 to April 2017) and the Grand Finale (April to September 2017), when Cassini flew just above Saturn's cloud tops. As the spacecraft was running out of fuel, the mission team deliberately plunged it into the planet's atmosphere in September 2017.
Cassini's Visible and Infrared Mapping Spectrometer (VIMS) uncovered another mystery. The spectrometer, which imaged the rings in visible and near-infrared light, identified unusually weak water-ice bands in the outermost part of the A ring. That was a surprise, because the area is known to be highly reflective, which usually is a sign of less-contaminated ice and thus stronger water ice bands.
The new spectral map also sheds light on the composition of the rings. And while scientists already knew that water ice is the main component, the spectral map ruled out detectable ammonia ice and methane ice as ingredients. But it also doesn't see organic compounds -- a surprise, given the organic material Cassini has discovered flowing from the D ring into Saturn's atmosphere.
The research signals the start of the next era of Cassini science, said NASA's Ames Research Center's Jeff Cuzzi, who's been studying Saturn's rings since the 1970s and is the interdisciplinary scientist for rings on the Cassini mission.
"We see so much more, and closer up, and we're getting new and more interesting puzzles," Cuzzi said. "We are just settling into the next phase, which is building new, detailed models of ring evolution -- including the new revelation from Cassini data that the rings are much younger than Saturn."
The new observations give scientists an even more intimate view of the rings than they had before, and each examination reveals new complexities, said Cassini Project Scientist Linda Spilker, based at NASA's Jet Propulsion Laboratory in Pasadena. "It's like turning the power up one more notch on what we could see in the rings. Everyone just got a clearer view of what's going on. Getting that extra resolution answered many questions, but so many tantalizing ones remain."
For the original and graphics see
https://www.jpl.nasa.gov/news/news.php?release=2019-114
-- From a Jet Propulsion Laboratory press release forwarded by Karen Pollard.
13. Did a Nearby Supernova Lead to Us?
Did ancient supernovae induce proto-humans to walk on two legs, eventually resulting in homo sapiens with hands free to build cathedrals, design rockets and snap iPhone selfies?
A paper published on May 28 in the Journal of Geology makes the case: Supernovae bombarded Earth with cosmic ray energy starting as many as 8 million years ago, with a peak some 2.6 million years ago. This ionized the lower atmosphere and set off a chain of events that feasibly ended with bipedal hominins such as homo habilis, dubbed “handy man.”
The authors believe atmospheric ionization probably triggered an enormous upsurge in cloud-to-ground lightning strikes that ignited forest fires around the globe. These infernos could be one reason ancestors of homo sapiens developed bipedalism -- to adapt in savannas that replaced torched forests in northeast Africa.
“It is thought there was already some tendency for hominins to walk on two legs, even before this event,” said lead author Adrian Melott, professor emeritus of physics & astronomy at the University of Kansas. “But they were mainly adapted for climbing around in trees. After this conversion to savanna, they would much more often have to walk from one tree to another across the grassland, and so they become better at walking upright. They could see over the tops of grass and watch for predators. It’s thought this conversion to savanna contributed to bipedalism as it became more and more dominant in human ancestors.”
Based on a tell-tale layer of iron-60 deposits lining the world’s sea beds, astronomers have high confidence that a supernovae exploded in Earth’s immediate cosmic neighbourhood -- between 100 and only 50 parsecs (330 to 160 light-years) away -- during the transition from the Pliocene Epoch to the Ice Age.
The researchers calculated the ionization of the atmosphere caused by cosmic rays from such a supernova, which appears to have been the closest one in a much longer series. They contend it would increase the ionization of the lower atmosphere by 50-fold. Usually cosmic rays don’t penetrate that far, but the more energetic ones from supernovae come right down to the surface. Ionization in the lower atmosphere meant an abundance of electrons would form more pathways for lightning strikes so there would be a lot more lightning bolts.
The probability that this lightning spike touched off a worldwide upsurge in wildfires is supported by the discovery of carbon deposits found in soils that correspond with the timing of the cosmic-ray bombardment.
“The observation is that there’s a lot more charcoal and soot in the world starting a few million years ago,” Melott said. “It’s all over the place, and nobody has any explanation for why it would have happened all over the world in different climate zones. This could be an explanation. That increase in fires is thought to have stimulated the transition from woodland to savanna in a lot of places. That’s thought to be related to human evolution in northeast Africa. Specifically, in the Great Rift Valley where you get all these hominin fossils.”
Melott said no such event is likely to occur again anytime soon. The nearest star capable of exploding into a supernova in the next million years is Betelgeuse, currently some 150 parsecs (500 light-years) from Earth. That's too far away to have effects anywhere near this strong. So, don’t worry about it. Worry about solar proton events. That’s the danger for us with our technology: a solar flare that knocks out electrical power. Just imagine months without electricity.
For the original text and references see https://news.ku.edu/2019/03/12/supernovae-zapped-earth-26-million-years-ago-researchers-wonder-if-they-prompted-human
-- From a University of Kansas press release forwarded by Karen Pollard.
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 2019 year starts at $40 for an ordinary
member, which includes an electronic subscription to our journal
'Southern Stars'.
15. 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.
For an application form contact the Executive Secretary
secretary@rasnz.org.nz,
16. Quote
"In the space of one hundred and seventy-six years the Lower Mississippi has shortened itself two hundred and forty-two miles. Therefore ... in the Old Oolitic Silurian Period the Lower Mississippi River was upward of one million three hundred thousand miles long... seven hundred and forty-two years from now the Lower Mississippi will be only a mile and three-quarters long... There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact." -- Mark Twain quoted on Phil Plait's 'Bad Astronomy' webpage, http://www.badastronomy.com/index.html
Alan Gilmore Phone: 03 680 6817
P.O. Box 57 alan.gilmore@canterbury.ac.nz
Lake Tekapo 7945
New Zealand
eNewsletter: No. 223, 20 July 2019 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. Apollo 11's 50th Anniversary and Future Plans
2. Conference Honours
3. The Solar System in August
4. Stargazers Getaway August 30-September 1
5. 2019 AAS Astrophotography Competition
6. Variable Star News
7. Joan Marie Galat in NZ
8. Space Weather Section Director Sought
9. Secretary for National Astronomical Society
10. Astro-tourism Centre Opened in Tekapo
11. Another Earth-Impactor Tracked
12. Saturn's Rings from Cassini's Close-ups
13. Did a Nearby Supernova Lead to Us?
14. How to Join the RASNZ
15. Gifford-Eiby Lecture Fund
16. Quote
1. Apollo 11's 50th Anniversary and Future Plans
It's the 50th anniversary of the Apollo 11 moon landing but nobody has been back since the end of the Apollo programme. Now everyone, it seems, wants to go the moon.
In January, Chang’e-4, a Chinese robotic spacecraft including a small rover, became the first ever to land on the far side of the moon. India is aiming to launch Chandrayaan-2 this month, its first attempt to reach the lunar surface. Even a small Israeli non-profit, SpaceIL, tried to send a small robotic lander there this year, but it crashed.
In the coming decades, boots worn by visitors from these and other nations could add their prints to the lunar dust. China is taking a slow and steady approach, and foresees its astronauts’ first arrival about a quarter of a century in the future. The European Space Agency has put out a concept of an international “moon village” envisioned for sometime around 2050. Russia has also described plans for sending astronauts to the moon by 2030, at last, although many doubt it can afford the cost.
In the United States, which sent 24 astronauts toward the moon from 1968 to 1972, priorities shift with the whims of Congress and presidents. But NASA in February was suddenly pushed to pick up its pace when Vice President Mike Pence announced the goal of putting Americans on the moon again by 2024, four years ahead of the previous schedule.
“NASA is highly motivated,” Jim Bridenstine, the former Oklahoma congressman and Navy pilot picked by President Trump to be the agency’s administrator, said in an interview. “We now have a very clear direction.”
For India, reaching the moon would highlight its technological advances. China would establish itself as a world power off planet. For the United States and NASA, the moon is now an obvious stop along the way to Mars.
The fascination with Earth’s celestial companion is not limited to nation-states. A bevy of companies has lined up in hopes of winning NASA contracts to deliver experiments and instruments to the moon. Blue Origin, the rocket company started by Jeff Bezos, founder and chief executive of Amazon, is developing a large lander that it hopes to sell to NASA for taking cargo — and astronauts — to the moon’s surface.
For three decades after the end of the Apollo program, few thought much about the moon. The United States had beaten the Soviet Union in the moon race. After Apollo 17, the last visit by NASA astronauts in 1972, the Soviets sent a few more robotic spacecraft to the moon, but they soon also lost interest in further exploration there.
NASA in those years turned its attention to building space shuttles and then the International Space Station. Its robotic explorers headed farther out, exploring Mars more intensely, as well as the asteroid belt and the solar system’s outer worlds.
-- The first paragraphs of a New York Times article by Kenneth Chang
on July 12. See the full article with images at
https://www.nytimes.com/2019/07/12/science/nasa-moon-apollo-artemis.html
Fred Watson has an introduction to the Moon at
https://www.abc.net.au/news/2019-07-16/pocket-guide-to-the-moon/11260558
2. Conference Honours
Two other awards made at the May Conference that were omitted from previous Newsletters:
Kyra Xavia of Dunedin received the Earth and Sky ‘Bright Star’ Award. Kyra has been extremely active in the promotion of astronomy and in the work of preserving the night sky from the effects of light pollution.
Gordon Hudson of Porirua received the President’s Service Award. Gordon was RASNZ President between 2012-14. He served as Secretary during this current term. Gordon has actively promoted astronomy and star parties since the 1980s and is an active observer/contributor.
-- From Keeping in Touch #33.
3. The Solar System in August
Dates and times shown are NZST (UT + 12 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.
THE SUN and PLANETS in AUGUST, Rise & Set, Magnitude & Constellation
August 1 NZST August 31 NZST
Mag Cons Rise Set Mag Cons Rise Set
SUN -26.7 Cnc 7.27am 5.27pm -26.7 Leo 6.46am 5.57pm
Merc 1.9 Gem 6.21am 4.19pm -1.8 Leo 6.46am 5.33pm
Venus -3.9 Cnc 7.21am 5.05pm -3.9 Leo 7.05am 6.17pm
Mars 1.8 Leo 8.04am 6.17pm .1.7 Leo 6.55am 5.57pm
Jup -2.4 Oph 1.07pm 4.16am -2.2 Oph 11.10am 2.08am
Sat 0.3 Sgr 3.20pm 6.18am 0.3 Sgr 1.15pm 4.15am
Uran 5.8 Ari 12.41am 11.15am 5.7 Ari 10.42pm 9.17am
Nep 7.8 Aqr 8.35pm 9.23am 7.8 Aqr 6.34pm 7.24am
Pluto 14.4 Sgr 3.46pm 6.43am 14.4 Sgr 1.45pm 4.43am
August 1 NZST August 31 NZST
Twilights morning evening morning evening
Civil: start 7.00am, end 5.55pm start 6.21am, end 6.23pm
Nautical: start 6.27am, end 6.28pm start 5.49am, end 6.55pm
Astro: start 5.54am, end 7.01pm start 5.17am, end 7.27pm
AUGUST PHASES OF THE MOON, times NZST (& UT)
New moon: Aug 1 at 3.12pm (03:12 UT)
First quarter: Aug 8 at 5.31am (Aug 7, 17:31 UT).
Full Moon: Aug 16 at 12.29am (Aug 15, 12:29 UT)
Last quarter Aug 24 at 2.56am (Aug 23, 14:56 UT)
New Moon: Aug 30 at 10:37pm (10:37 UT)
PLANETS in August.
MERCURY, VENUS and MARS: during the last 8 days of August the three terrestrial planets are all in Leo - with the Sun (see table above). Not surprisingly, the three planets are unobservable during August. On the 30th they are joined by the New Moon with all three planets at conjunction with our satellite during the 24 hours. Again, an unobservable event.
Remembering that this is as viewed from the Earth, it means that there is effectively a line-up of all 4 inner planets and Sun.
JUPITER and SATURN meanwhile are visible much of the night rising well before the time of Sunset and setting after midnight. Jupiter is stationary on the 11th when it will be just under 7° from Antares.
This month's lunar occultation of Saturn is on the 12th. It is visible from most of the North Island but is a miss from the South Island. The southern limit grazing occultation of Saturn occurs along a west to east band which includes Carterton and Masterton. The extreme outer edge is at Greytown where Saturn only just touches the moon. Further north increasing amounts of Saturn are hidden until the latitude of Otaki from where Saturn is, briefly, fully obscured The duration of the occultation increases the further north one goes, more than an hour at North Cape.
Predictions of times of the occultation for a number of places in the North Island and Eastern Australia are available on the Occultation Section web site
PLUTO is close behind Saturn, rising and setting half an hour later.
URANUS remains a morning object in Aries.
NEPTUNE, is in Aquarius. By the end of August it is in the sky most of the night.
BRIGHTEST ASTEROIDS in AUGUST, magnitude, constellation, time of transit
AUGUST 1 NZDT AUGUST 31 NZST
Mag Cons transit Mag Cons transit
(1) Ceres 8.4 Lib 7.38am 8.9 Sco 5.59pm
(4) Vesta 8.1 Ari 6.54am 7.7 Tau 5.24am
(15) Eunomia 8.5 Aqr 1.12am 8.5 Aqr 10.45pm
CERES moves into Scorpius on the 1st. It passes between the second magnitude stars delta and beta Sco midmonth and ends August just over 5° from Antares and 9° from Jupiter.
VESTA is in the morning sky, rising at 1.30 am on the 1st and at midnight on the 31st. It moves into Taurus on the 11th.
EUNOMIA is at opposition on August 12 with a magnitude 8.2. It will then be in the sky most of the night.
-- Brian Loader
4. Stargazers Getaway August 30 - September 1
The North Otago Astronomical Society Inc, would like to invite you to Stargazers Getaway 2019, over the weekend of, Friday August 30th to Sunday September 1st at Camp Iona in Herbert.
This is the second year back for our iconic Stargazers Getaway, building on last year's camp, the first in over 10 years!
With expressions for attendees already coming in, this year is promising to be bigger and better!!
Children under 5 are free
Students 5-17 - $20 p/night, $35 for both
Adults +18 - $35 p/night, $60 for both
Day visits for talks - $5 p/day
Interested people who would like to either attend, speak or present a poster paper are asked to email the Stargazers Getaway Co-ordinator, Damien McNamara, as numbers are limited at :- solaur.science@gmail.com
5. 2019 AAS Astrophotography Competition
Calling all Astrophotographers: get your entries in for the 2019 New Zealand Astrophotography competition before the competition cut-off date of September 30. Winners will be announced at the Auckland Astronomical Society's annual Burbidge dinner.
This year's judge is the "Bad Astronomer" Phil Plait, American astronomer, sceptic, writer and popular science blogger. Phil is best known for debunking misconceptions in astronomy but is also a well-known astrophotography enthusiast.
Prizes are one year subscriptions to Australian Sky & Telescope and a $300 Astronz gift voucher. As well the Auckland Astronomical Society will provide a cash prize for each category winner.
For categories, prize details, competition rules and entry forms see the homepage of the Auckland Astronomical Society website
https://www.astronomy.org.nz/new/public/default.aspx
-- Abridged from a note to the nzastronomers group by Jonathan Green.
6. Variable Star News
False Flare
A flurry of posts was spawned on the Variable Stars South (VSS) Google discussion group starting in June. An observation was reported by Marcos da Silva of a light outburst of the 4th magnitude star Gamma Ophiuchi. The brightening was about 2 magnitudes. As this was not a known variable star a number of questions were asked and more information was provided over several posts. The observation was a short video over quite a large area of sky (60 degrees across) taken with a meteor camera, part of the Brazilian Meteor Observation Network (BRAMON). The video was taken in South America and the time of day was soon after nightfall; the video was also posted. It was eventually proposed that the phenomenon was probably due to a flash from an earth-orbiting satellite coincidentally at the same position as the star. A web-site that publishes predictions of flash events had a couple of occurrences near Gamma Oph at the time of observation. It is intriguing that the equipment launched into earth orbit can unknowingly interfere with our observations of stellar objects far away. Another explanation proposed, in this case celestial, was an incoming meteor aligned head-on with the camera. The video is available on the VSS website under “News Items” or using the following link: https://www.variablestarssouth.org/unusual-brightening-of-gamma-ophiuchi/
The comments on the flash event were mixed in with a lot of discussion of basic photometric procedures such as making and filing darks and flats. It is proposed that an updated guide to procedures for photometric systems and software will be produced, distilling the best methodologies from this discussion.
AAVSO
Three more CHOICE education courses are being offered in the remainder of the 2019 year. Notable is Exoplanet Observing, November 4 - December 6. For the full list refer to the AAVSO web-site or the July monthly Circular.
VSS Symposium in 2000
The Variable Stars South Symposium 6 (VSS S6) will be held on Friday April 10th, the first day of the 29th National Australian Convention of Amateur Astronomers, Easter weekend 2020, 10-13 April. The NACAA XXIX event will be held at Parkes, a NSW Regional Town, and hosted by the Central West Astronomical Society. Parkes is the site of the Parkes Radio Telescope, the famous 64 m steerable dish which has been operating since 1961. The website for the NACCA event is https://nacaa.org.au/2020/about. We will advise details of the VSS Symposium when they are posted on the VSS website.
Star Alert
The variable V854 Centauri appears to have commenced a decline. This star is a R Coronae Borealis (RCB) type star; this class of star undergoes large fades in brightness intermittently due to obscuration by dust clouds in the stellar atmosphere. Each event tends to be unique in duration and magnitude decline.
-- Alan Baldwin
7. Joan Marie Galat in NZ
Joan Marie Galat is a Canadian-based international award-winning author whose career began at the age of 12, when she was hired as a newspaper columnist. Now she is the author of more than 20 books, including a Canadian best seller. Joan shares her love of the night sky in her Dot to Dot in the Sky series (Whitecap Books), which partners sky science with the stories early cultures first told to explain their observations. Dark Matters—Nature’s Reaction to Light Pollution (Red Deer Press) offers personal stories, revealing how light at night impacts wildlife. Other titles include Black Holes and Supernovas, The Discovery of Longitude, and an upcoming title: Absolute Expert – Space (National Geographic Kids).
A professional speechwriter, former radio show host, and frequent presenter, Joan has travelled across Canada and from the Arctic Circle to Australia, South Korea, and the USA to deliver presentations promoting science and literacy. In 2016, Joan spoke about the night sky environment at a United Nations event in Seoul. Featured at the Jasper Dark Sky Festival and numerous other night sky events, she presented at the International Dark-Sky Association annual meeting in 2018. When not writing or talking about the night sky, Joan enjoys stiltwalking and can sometimes be seen in costume at Edmonton festivals.
PRESENTATIONS and WORKSHOP
Joan will be touring in New Zealand October 14 – 28, 2019. She is available for adult, family, and student presentations that explore the world through science and story. You can watch Joan’s speaker demo and book trailers, and view book descriptions at www.joangalat.com.
-- Forwarded by John Hearnshaw.
8. Space Weather Section Director Sought
Dear Members,
Following his valuable term of service as Director of the Space Weather Section, Damien McNamara has chosen to step down from that position. Damien has become more involved with the challenges brought by increasing light pollution from new and additional sources. For and on behalf of the Council, I would like to thank Damien for his effort, energy and leadership.
Damien stepped down as Director on 5 May 2019. At this time, Council is inviting any Member of the Society who wishes to be considered for the Directorship of the Space Weather Section to apply. Applications close at 5 p.m. 12 April 2019.
Applications are to be sent by post or email to the Secretary by the above deadline; secretary@rasnz.org.nz.
Applications are to include
1. a statement of interest which sets out the Member's interests in Space Weather, their past experience, their plans for leading the Section and any new initiatives for the Section's members, and
2. the names and contact details of two referees of whom Council can request further information about the applicant. Applications are to be no more than two sides of A4 in length, font size at least 12, font either Times New Roman or Ariel.
Yours,
Nicholas Rattenbury, RASNZ President.
9. Secretary for National Astronomical Society
The Royal New Zealand Astronomical Society (RASNZ) is seeking a suitable person to take on the voluntary role of Secretary. This is an important role within RASNZ. The new appointee will be a key member of RASNZ helping administer and make strategic decisions for RASNZ.
No formal qualifications or prior experience in a similar role are necessary, and, this role does not preclude holders of positions in other astronomical societies. However, knowledge of RASNZ rules
(https://www.rasnz.org.nz/images/articleFiles/Council/Rules2015.pdf), history and operations would be beneficial to performing the duties. Templates created by former holders of this position will be made available. This role can be undertaken entirely from the home office but attendance at the RASNZ Council's AGM held once a year at the RASNZ annual conference is strongly encouraged.
The responsibilities of the Secretary include:
(i) Receive and send physical and electronic correspondence on behalf of the RASNZ, document it and draw appropriate people's attention to the
correspondence;
(ii) Compile the Council's Annual Report and prepare it for approval by the Council in time for publication in the March issue of Southern Stars, and
(iii) Maintain a record of meetings and motions, both physical and electronic.
This offers a great opportunity for someone to contribute to the nationwide support and promotion of astronomy, science education and related research.
Contact: Nick Rattenbury (nicholas.rattenbury@gmail.com)
President - RASNZ
10. Astro-tourism Centre Opened in Tekapo
An $11 million, fully immersive dark sky experience is now open in Tekapo combining Māori astronomy and science.
Dark Sky Project, formerly Earth and Sky, opened the doors to its new 1140sqm building on the Tekapo lakefront on July 1 and is a joint venture between Ngāi Tahu Tourism and co-founders Graeme Murray and Hide Ozawa.
The centre includes the Dark Sky Diner, and will be the departure point for the astro-tourism business' outdoor, evening stargazing experiences.
Mana whenua from Arowhenua, Waihao and Moeraki rūnanga blessed the building named Rehua on Monday while Governor-General of New Zealand, Dame Patsy Reddy, opened the new experience.
Murray said it "has been incredible" to watch the building take shape, especially the moment the large observatory dome was craned on in April.
"Ever since Hide and I stood on the summit of Ōtehīwai (Mt John) looking up at the night sky 15 years ago, it has been our dream to develop a home for astronomy in the heart of the Aoraki Mackenzie International Dark Sky Reserve, so that we could inspire a lifelong understanding and passion for our night skies."
The dome houses the 125-year-old Brashear Telescope, which stands up to nine metres tall and was in storage for five decades before being restored in Fairlie over the past two years. The telescope is now part of the new 45-minute Dark Sky Experience.
The centre will tell the stories of local iwi and runanga's relationship with the night sky, and how it has developed.
It is located at the heart of the Aoraki/Mt Cook Mackenzie International Dark Sky Reserve - the largest dark sky reserve in the world and the only one of its kind in the Southern Hemisphere.
Te Rūnanga o Ngāi Tahu Kaiwhakahaere Lisa Tumahai said the $3m in government funding provided by the Tourism Growth Partnership fund in 2016 was the kick-start the $11 million development needed. "It will further enhance the Ngāi Tahu contribution to regional development and job creation – mō tātou, ā, mō ka uri ā muri ake nei. I truly commend mana whenua and all involved in the creation of an authentic experience that will see our ancestors' stories told to the world."
To ensure the Dark Sky Experience was authentic, Dark Sky Project worked with mana whenua from Arowhenua, Waihao and Moeraki, leading Māori astronomy expert Professor Rangi Mātāmua and the University of Canterbury to bring to life the stories of the universe.
-- From The Timaru Herald of July 2. See the original text with photos at https://www.stuff.co.nz/travel/destinations/nz/113896886/new-star-attraction-opens-in-tekapo-combining-mori-astronomy-and-science
11. Another Earth-Impactor Tracked
On June 22 around 21:26 UT (17:26 local time), a roughly 5-metre object entered the atmosphere over the Caribbean Sea, and exploded at an altitude of about 25 km over the sea surface, releasing an energy roughly equivalent to 3 kilotons of TNT. The explosion was first detected by the geostationary Lightning Mapper (GLM) instrument on board the GOES-16 geostationary satellite.
A couple of days later the NASA JPL team realised that an object appearing on the NEO Confirmation Page as A10eoM1, discovered on the morning of June 22 by the ATLAS survey in Hawaii, could be a good candidate progenitor for the fireball event. This tentative identification allowed the Pan-STARRS team to locate three pre-discovery detections of the object in images obtained by the Pan-STARRS2 telescope a couple of hours before the ATLAS discovery. Adding the corresponding astrometry to the orbit determination confirmed the identification of the object with the fireball event, pinpointing the impact location with a precision of a few hundred km.
The asteroid has now been designated 2019 MO and is the fourth known impactor detected by surveys before impact with our planet.
Past impactors have been 2008 TC3, on 2008 October 7, about 4 metres across, found 20 hours before impact; 2014 AA on 2014 January 2, 2-4 metres across, found about 22 hours before impact; 2018 LA found on 2018 June 2, 2-5 metres across, found 8 hours before impact; and 2019 MO, 4-8 metres across, recorded 13 hours before impact.
For more information see http://neo.ssa.esa.int
-- Copied from the European Space Agency's NEO Coordination Centre Newsletter July 2019. See the above website for the original.
12. Saturn's Rings from Cassini's Close-ups
As NASA's Cassini spacecraft (https://solarsystem.nasa.gov/cassini) dove close to Saturn in its final year, the spacecraft provided intricate detail on the workings of Saturn's complex rings, new analysis shows.
Although the mission ended in 2017, science continues to flow from the data collected. A new paper published on June 13 in Science describes results from four Cassini instruments taking their closest-ever observations of the main rings.
Findings include fine details of features sculpted by masses embedded within the rings. Textures and patterns, from clumpy to straw-like, pop out of the images, raising questions about the interactions that shaped them. New maps reveal how colours, chemistry and temperature change across the rings.
Like a planet under construction inside a disk of protoplanetary material, tiny moons embedded in Saturn's rings (named A through G, in order of their discovery) interact with the particles around them. In that way, the paper provides further evidence that the rings are a window into the astrophysical disk processes that shape our solar system.
The observations also deepen scientists' understanding of the complex Saturn system. Scientists conclude that at the outer edge of the main rings, a series of similar impact-generated streaks in the F ring have the same length and orientation, showing that they were likely caused by a flock of impactors that all struck the ring at the same time. This shows that the ring is shaped by streams of material that orbit Saturn itself rather than, for instance, by cometary debris (moving around the Sun) that happens to crash into the rings.
"These new details of how the moons are sculpting the rings in various ways provide a window into solar system formation, where you also have disks evolving under the influence of masses embedded within them," said lead author and Cassini scientist Matt Tiscareno of the SETI Institute in Mountain View, California.
At the same time, new puzzles have arisen and old mysteries have deepened with the latest research. The close-up ring images brought into focus three distinct textures -- clumpy, smooth and streaky -- and made it clear that these textures occur in belts with sharp boundaries. But why? In many places the belts aren't connected to any ring characteristics that scientists have yet identified.
"This tells us the way the rings look is not just a function of how much material there is," Tiscareno said. "There has to be something different about the characteristics of the particles, perhaps affecting what happens when two ring particles collide and bounce off each other. And we don't yet know what it is."
The data analysed were gathered during the Ring Grazing Orbits (December 2016 to April 2017) and the Grand Finale (April to September 2017), when Cassini flew just above Saturn's cloud tops. As the spacecraft was running out of fuel, the mission team deliberately plunged it into the planet's atmosphere in September 2017.
Cassini's Visible and Infrared Mapping Spectrometer (VIMS) uncovered another mystery. The spectrometer, which imaged the rings in visible and near-infrared light, identified unusually weak water-ice bands in the outermost part of the A ring. That was a surprise, because the area is known to be highly reflective, which usually is a sign of less-contaminated ice and thus stronger water ice bands.
The new spectral map also sheds light on the composition of the rings. And while scientists already knew that water ice is the main component, the spectral map ruled out detectable ammonia ice and methane ice as ingredients. But it also doesn't see organic compounds -- a surprise, given the organic material Cassini has discovered flowing from the D ring into Saturn's atmosphere.
The research signals the start of the next era of Cassini science, said NASA's Ames Research Center's Jeff Cuzzi, who's been studying Saturn's rings since the 1970s and is the interdisciplinary scientist for rings on the Cassini mission.
"We see so much more, and closer up, and we're getting new and more interesting puzzles," Cuzzi said. "We are just settling into the next phase, which is building new, detailed models of ring evolution -- including the new revelation from Cassini data that the rings are much younger than Saturn."
The new observations give scientists an even more intimate view of the rings than they had before, and each examination reveals new complexities, said Cassini Project Scientist Linda Spilker, based at NASA's Jet Propulsion Laboratory in Pasadena. "It's like turning the power up one more notch on what we could see in the rings. Everyone just got a clearer view of what's going on. Getting that extra resolution answered many questions, but so many tantalizing ones remain."
For the original and graphics see
https://www.jpl.nasa.gov/news/news.php?release=2019-114
-- From a Jet Propulsion Laboratory press release forwarded by Karen Pollard.
13. Did a Nearby Supernova Lead to Us?
Did ancient supernovae induce proto-humans to walk on two legs, eventually resulting in homo sapiens with hands free to build cathedrals, design rockets and snap iPhone selfies?
A paper published on May 28 in the Journal of Geology makes the case: Supernovae bombarded Earth with cosmic ray energy starting as many as 8 million years ago, with a peak some 2.6 million years ago. This ionized the lower atmosphere and set off a chain of events that feasibly ended with bipedal hominins such as homo habilis, dubbed “handy man.”
The authors believe atmospheric ionization probably triggered an enormous upsurge in cloud-to-ground lightning strikes that ignited forest fires around the globe. These infernos could be one reason ancestors of homo sapiens developed bipedalism -- to adapt in savannas that replaced torched forests in northeast Africa.
“It is thought there was already some tendency for hominins to walk on two legs, even before this event,” said lead author Adrian Melott, professor emeritus of physics & astronomy at the University of Kansas. “But they were mainly adapted for climbing around in trees. After this conversion to savanna, they would much more often have to walk from one tree to another across the grassland, and so they become better at walking upright. They could see over the tops of grass and watch for predators. It’s thought this conversion to savanna contributed to bipedalism as it became more and more dominant in human ancestors.”
Based on a tell-tale layer of iron-60 deposits lining the world’s sea beds, astronomers have high confidence that a supernovae exploded in Earth’s immediate cosmic neighbourhood -- between 100 and only 50 parsecs (330 to 160 light-years) away -- during the transition from the Pliocene Epoch to the Ice Age.
The researchers calculated the ionization of the atmosphere caused by cosmic rays from such a supernova, which appears to have been the closest one in a much longer series. They contend it would increase the ionization of the lower atmosphere by 50-fold. Usually cosmic rays don’t penetrate that far, but the more energetic ones from supernovae come right down to the surface. Ionization in the lower atmosphere meant an abundance of electrons would form more pathways for lightning strikes so there would be a lot more lightning bolts.
The probability that this lightning spike touched off a worldwide upsurge in wildfires is supported by the discovery of carbon deposits found in soils that correspond with the timing of the cosmic-ray bombardment.
“The observation is that there’s a lot more charcoal and soot in the world starting a few million years ago,” Melott said. “It’s all over the place, and nobody has any explanation for why it would have happened all over the world in different climate zones. This could be an explanation. That increase in fires is thought to have stimulated the transition from woodland to savanna in a lot of places. That’s thought to be related to human evolution in northeast Africa. Specifically, in the Great Rift Valley where you get all these hominin fossils.”
Melott said no such event is likely to occur again anytime soon. The nearest star capable of exploding into a supernova in the next million years is Betelgeuse, currently some 150 parsecs (500 light-years) from Earth. That's too far away to have effects anywhere near this strong. So, don’t worry about it. Worry about solar proton events. That’s the danger for us with our technology: a solar flare that knocks out electrical power. Just imagine months without electricity.
For the original text and references see https://news.ku.edu/2019/03/12/supernovae-zapped-earth-26-million-years-ago-researchers-wonder-if-they-prompted-human
-- From a University of Kansas press release forwarded by Karen Pollard.
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 2019 year starts at $40 for an ordinary
member, which includes an electronic subscription to our journal
'Southern Stars'.
15. 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.
For an application form contact the Executive Secretary
secretary@rasnz.org.nz,
16. Quote
"In the space of one hundred and seventy-six years the Lower Mississippi has shortened itself two hundred and forty-two miles. Therefore ... in the Old Oolitic Silurian Period the Lower Mississippi River was upward of one million three hundred thousand miles long... seven hundred and forty-two years from now the Lower Mississippi will be only a mile and three-quarters long... There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact." -- Mark Twain quoted on Phil Plait's 'Bad Astronomy' webpage, http://www.badastronomy.com/index.html
Alan Gilmore Phone: 03 680 6817
P.O. Box 57 alan.gilmore@canterbury.ac.nz
Lake Tekapo 7945
New Zealand
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