RASNZ Electronic Newsletter December 2016

The RASNZ Email newsletter is distributed by email on or near the 20th of each month. If you would like to be on the circulation list This email address is being protected from spambots. You need JavaScript enabled to view it. for a copy. The latest issue is below.

Email Newsletter Number 192

Affiliated Societies are welcome to reproduce any item in this email newsletter or on the RASNZ website http://www.rasnz.org.nz/ in their own newsletters provided an acknowledgement of the source is also included.


1. IAU Standardizes 212 Traditional Star Names
2. Aurora & Solar Section - Director Sought
3. The Solar System in January
4. Star Parties in Early 2017
5. 2017 Conference - Call for Papers
6. Variable Star News - R Aurigae
7. Science Can Inform Better Lighting Decisions
8. John Glenn
9. Icy Ceres
10. How to Join the RASNZ
11. Gifford-Eiby Lecture Fund
12. Kingdon-Tomlinson Fund

Standardizes 212 Traditional Star Names ----------

In a series of resolutions from 1922 to 1930, the International Astronomical Union approved standard spellings, abbreviations, and definitions for the 88 official constellations. Before this reform, several other constellations were recognized by some but not all astronomers: for instance, Quadrans Muralis, now preserved only in the name of the Quadrantid meteor shower. Even for the universally recognized constellations, there was no consensus where one stopped and another started. That caused grave problems with respect to newly discovered variable stars, because variable-star designations need to name the constellation that the star is in.

The IAU constellation reforms were wildly successful, and there was widespread hope that a similar procedure could be applied to traditional star names such as Sirius, the brightest star in the night sky. But that did not happen, for many reasons.

First, there was no urgent need among professional astronomers, because all the stars with traditional names also have official designations. Sirius, for instance, is unambiguously designated as Alpha Canis Majoris. Second, whereas 88 constellations suffice to tile the entire sky, the star-naming problem is open-ended. Several thousand stars are visible to the unaided eye, and millions more are visible through modest-sized telescopes. No way are all of those going to get colloquial names -- but where to stop?

Finally, the star-name situation was far more chaotic than the constellations before the IAU reforms. The Yale Bright Star Catalog lists approximately 900 names that have been used at one time or another for approximately 400 stars. Most of those stars have multiple names, and a fair number of names have been applied to multiple stars. What a mess!

The IAU has now created order out of this chaos, giving official status to 212 of these names. That brings the total number of IAU-approved star names to 227, including: 14 stars with exoplanets approved in December 2015 212 bright stars with traditional-sounding names, almost all of them in use by 1900 1 faint but very important star discovered in 1915: Proxima Centauri, the closest star to the Sun.

With any luck, the IAU's standardization of star names will prove as successful as the constellations it standardized almost a century ago. Expect the myriad conflicting usages in popular books and magazines to converge toward the IAU names over the next several years.

Why hasn't this been more of a problem in the past? Largely because most of these "popular" star names aren't really all that popular — and never have been. The name Sirius has been in continuous use with minor spelling variations for more than two millennia, but that's a rare exception. Roughly half the star names in the IAU list, while traditional sounding, were in fact invented after 1800. There was never a time when everyday people knew hundreds of stars by name — these "traditional" names are almost certainly used more widely today than ever before.

-- Abridged from the article by Tony Flanders at http://www.skyandtelescope.com/astronomy-news/iau-standardizes-212-traditional-star-names/ Informative comments follow it.

The IAU list can be downloaded from http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt

For a classical textbook on star names see "Star Names - Their Lore and Meaning" by Richard Hinkley Allen, first published in 1899, reprinted by Dover in 1963. ISBN 0-486-21079-0.

2. Aurora & Solar Section - Director Sought

I have decided to relinquish directorship of the Section at the end of this year. I became involved in assisting in administering the Section in 1985 and gradually got more involved over the next few years. After these three decades I'd like to now devote my time to other projects; including hopefully more observational astronomy.

I don't know whether there is anyone out there that is interested in taking over the running of the Section. I hope that there might be. It would no doubt be in a different form. It could even be split into a separate Aurora Section and a Solar Section. The only requirement for it to be a Section of the RASNZ is that the Director needs to be an RASNZ member and that the RASNZ Council approves it being a Section.

My reasons for running the Section have been twofold: to compile a record of the occurrences and descriptions of Aurorae Australis and the Sun, and to encourage their observation. These observations have been detailed in Circulars, starting with auroral observations early in 1979, then by Dennis Goodman who was the Section Director at that time. I am in the process of scanning all these records and uploading them to the RASNZ Website.

I intend publishing two more Newsletters that will summarise observation up to the end of this year, and one more Circular detailing 2016 observations.

I am happy to discuss with anyone interested in continuing this Section in some form or other or they May apply directly to the RASNZ Council via its Secretary.

-- Bob Evans.

3. The Solar System in January

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.

Sunrise, sunset and twilight times in january

                          January  1  NZDT              January 31  NZDT
                  morning  evening              morning  evening
       SUN: rise: 5.48am,  set: 8.59pm     rise: 6.22am,  set: 8.44pm
Civil:    starts: 5.18am, ends: 9.31pm   starts: 5.54am, ends: 9.13pm
Nautical: starts: 4.35am, ends:10.14pm   starts: 5.16am, ends: 9.51pm
Astro:    starts: 3.44am, ends:11.04pm   starts: 4.34am, ends:10.33pm

January PHASES OF THE MOON (times as shown by GUIDE)

          First quarter: January  6 at  8.47 am (Jan  5, 19:47 UT)
  Full moon:     January 13 at 12.34 am (Jan 12, 11:34 UT)
  Last quarter   January 20 at 11.13 am (Jan 19, 22:13 UT)
  New moon:      January 28 at  1.07 pm (00:07 UT)

The Earth is at perihelion, its closest to the Sun for the year, on January 4 at 11 pm (NZDT), 10 hours UT. The Earth will then be 0.9833 AU, 147.1 million km, from the centre of the Sun, which will have an apparent angular diameter of 32.53 arc-minute.

The planets in january 2017

Venus remains the obvious bright planet in the evening sky with Mars, much fainter, only a few degrees higher. Mercury will be a morning object visible an hour before sunrise during the second half of the month. Jupiter and Saturn are also morning planets. Jupiter rises just before midnight by the end of January. Saturn will be readily visible to the east by the end of the month.

EVENING PLANETS VENUS will remain brilliant in the evening sky throughout January reaching magnitude -4.7 by the 31st. It will get a little lower in the western sky, setting by 10.30 pm at the end of January. The planet starts January in Aquarius moving on into Pisces on the 23rd.

On the 13th Venus will pass Neptune, magnitude 7.9. At their closest their separation will be 21 arc-minutes, less than the diameter of the full moon. By 10 pm, when the sky should be dark enough to see Neptune in binoculars, the two planets will be 36 arc-minutes apart with Neptune to the left of and slightly higher than Venus

The crescent moon will be a couple of degrees below Venus on January 2.

MARS is a little higher than Venus throughout January, its brightness fading slightly from magnitude 0.9 to 1.1 during the month. It is 12° from Venus on the 1st, the separation decreasing to 5.5° by the 31st. On January 19 Mars will move into Pisces from Aquarius.

Early in January, Mars and Neptune are very close, the separation being only 4.9 arc-minutes on the 1st about 1-6th of the diameter of the full moon. Neptune is then to the lower left of Mars with a magnitude 7.9 so visible in binoculars. There will be no star nearby which could be confused with Neptune.

Mars will move away from Neptune during the following evenings but on the 3rd the two, now 1.5° apart, will be joined by the 25% lit crescent moon. By the time the sky is dark enough to see the planets, the moon will have just moved past them and be about 1° from Mars. A few hours earlier the moon will occult first Neptune and then Mars, events visible from the parts of the north Pacific.

MORNING PLANETS JUPITER is the brightest planet in the morning sky, it will be joined there by Saturn and Mercury during the month. On the 1st Jupiter rises at 1.25 am, almost 2 hours earlier by the 31st, that is shortly before midnight. In Virgo, Jupiter starts the month 4.4° from Spica. Its slowing, easterly movement brings it to just over 3.5° from the star by the end of the month.

On the morning of the 20th, the moon at last quarter, will be just over 5° from Jupiter and 7° from Spica.

SATURN, emerging into the morning sky after its December conjunction, will rise about 80 minutes before the Sun on the 1st and more than three and a half hours earlier than the Sun on the 31st. The planet is in Ophiuchus at magnitude 0.5.

On the morning of the 25th, the crescent moon will be just over 5° below Saturn as seen from New Zealand.

MERCURY also emerges from the Sun into the morning sky following its inferior conjunction at the end of December. At first it will be too close to the Sun to see. The westerly retrograde motion of the planet will move it quite rapidly away from the Sun, so that when stationary on the 9th, it will rise 75 minutes before the Sun. Mercury will also have brightened from magnitude 2.9 to 0.4, so it May be briefly visible very low to the east-south-east before the sky gets too bright to see the planet. It will then be some 6.5° to the lower right of Saturn.

Mercury’s angular distance from the Sun continues to increase for another 10 days until it reaches its greatest elongation on the morning of the 20th. It will then be 24° from the Sun at magnitude -0.2, rising 100 minutes before the Sun and so readily visible, if low, up to an hour or less before sunrise. The planet continues to be briefly visible at this sort of time for the rest of the month.

The moon, as a very thin crescent, will be 5° to the left of Mercury on the morning of the 26th.

OUTER PLANETS URANUS, at magnitude 5.8, remains in Pisces and is observable all evening. It will set after midnight, about 12.30 am by the 31st. The moon, just past first quarter, will be just over 4° to the upper right of Uranus on the 6th.

NEPTUNE is in Aquarius at magnitude 7.9 throughout January. It conjunctions during the month with Mars, on the 1st, and Venus, on the 13th are described in the notes for those planets.

MINOR PLANETS (1) CERES starts the month in Cetus but moves into Pisces on the 8th. The asteroid fades a little during the month from magnitude 8.6 to 9.0. Its distance from Uranus increases from 7.2 to 9.5° during the month. The asteroid sets just after midnight at the end of January.

(4) VESTA starts January in Cancer moving on into Gemini on the 19th. It ends the month about 3.5° above and to the right of Pollux, beta Gem, mag 1.2. Vesta is at opposition on the 18th when its magnitude will be 6.2

(18) MELPOMENE is also in Cetus between 11 and 15 degrees from Ceres. The asteroid continues to fade from magnitude 9.7 to 10.3 during January. Melpomene is on the opposite side of Ceres to Uranus. The asteroid is also a few degrees from comet Harrington-Wilson during January.

(9) METIS and (14) IRENE are both in Leo, about 6° apart. Their magnitudes brighten to 9.5 and 9.4 respectively on the 31st. Metis will then be just over 12° to the right of Regulus, mag 1.4, in a direction towards delta Leo, mag 2.5. Irene will be below Metis. They rise about 10.30 pm.

(15) EUNOMIA also brightens to magnitude 9.5 by the 31st. It will then be in Sextans, 2.5° to the right of alpha Sex, mag 4.5. Eunomia rises just before 9pm.

COMETS. Two reasonably bright comets should be visible in binoculars during January.

P/Honda-Mrkos-Pajdusakova (45P) at magnitude 7.7 is 16° to the lower left of Venus on the 1st. The 9% lit crescent moon will be 5.5° to the right and slightly lower than the comet. At 10 pm the comet will have an 8° altitude, the moon being a degree lower. Subsequent evenings the comet will get lower in the evening sky and soon be lost to view.

D/Harrington-Wilson (D/1952 B1) is in Cetus, magnitude 8.9 on the 1st and 8.6 on the 31st. It will be quite close to the asteroid (8) Melpomene, their separation being about 6° on the 1st, 4° mid month and just over 6° by the 31st. On the 23rd the comet is less than a degree below the star Menkar, alpha Cet, mag 2.5.

-- Brian Loader

4. Star Parties in Early 2017

Central Star Party: Thursday 19th – Monday 23rd January. The Central Star Party has been established to hold annual star parties in the central North Island for the benefit of the astronomical community of the North Island of New Zealand. The goal of the organisers is to provide a fun social astronomical gathering laced with talks and activities and star gazing. The second Central Star Party is Thursday 19th to Mon 23rd January 2017 and be held at the Tuki Tuki Camp site in the Hawkes Bay. This is the site of many previous star parties. There is a brand new hall, with two additional meeting rooms for alternate meetings, a new kitchen and three new dormitories. Accommodation is tenting, staying in the dormitories or using one of the six powered caravan sites. For more details go to - http://www.censtar.party/

Stardate NI (North Island): Friday 27th – Sunday 29th January. Richard Hall writes, ‘Stardate 2017 is to be held at Stonehenge Aotearoa on January 27th to 29th 2017. However, participants May arrive earlier or stay later than these dates. In addition to a 3-day program of astronomical lectures, workshops and observing, we have movies, a geology field trip, live music and of course barbecues. This is an attractive site with good swimming holes in the Ruamahanga River just down the road. The wine growing areas of Martinborough, Gladstone and Masterton are within 30 minutes. There is a thriving tourist industry with many activities and venues available within the same distance’. For further information phone (06) 377 1600 or visit www.astronomynz.org

Stardate SI (South Island): Friday 17th – Monday 20th February. Stardate SI will be held at a "Christian" hostel and camp at Staveley between Friday February Friday 17th to Monday 20th February 2017. Organiser Euan Mason writes, ‘There's nothing particularly religious about Stardate, although Phil Barker reports a religious experience when he views the cosmos through his twin brother Kevin's 5" Zeiss refractor. Come and join us for this magnificent celebration of astronomy, science, and the cosmos at large’. For more details see - http://www.treesandstars.com/stardate/

-- From 'Keeping in Touch' #19. 23 October 2016

5. 2017 Conference - Call for Papers

It is a pleasure to announce that the next conference of the Royal Astronomical Society of New Zealand (RASNZ) will be held in Dunedin over the weekend of 12th -14th May 2017. Our guest speaker will be Professor Joss Bland-Hawthorn from the University of Sydney, and the Fellows’ Lecture for 2017 will be delivered by Jennie McCormick. Titles and abstracts for these talks will be released when they are available.

The RASNZ standing conference committee (SCC) invites and encourages anyone interested in New Zealand Astronomy to submit oral or poster papers, with titles and abstracts due by 1st April 2017 or at such time as the SCC deems the conference programme to be full. The link to the paper submission form can be found on the RASNZ Conference website www.rasnz.org.nz/Conference. Please note that you must be registered for the conference to give an oral presentation and for your convenience a link has been provided if you wish to do this when you register.

Following the conference, the 11th Trans-Tasman Symposium on Occultations (TTSO11) will be held at the conference venue on Monday/Tuesday 15th - 16th May. Details of the registration for TTSO11 will be available with the registration form for the conference, and paper submissions should be sent directly to the convenor Murray Forbes (This email address is being protected from spambots. You need JavaScript enabled to view it.). Note that this workshop will only be held if there is sufficient interest, so please register as soon as you can. We look forward to receiving your submissions and seeing you at the conference. Please feel free to forward this message to anyone who May find it of interest.

For further information on the RASNZ conference, registration details and associated events please visit the conference website at www.rasnz.org.nz/Conference

-- Warwick Kissling, RASNZ Standing Conference Committee.

6. Variable Star News - R Aurigae

Featured in the American Association of Variable Star Observers (AAVSO) December 2016 monthly Newsletter was the variable star R Aurigae which undergoes a large fluctuation in magnitude (visual 6.7 to 13.9). This star is a long period variable (average period 457.5 days) of the Mira type and one that exhibits a hump on the rising curve. The article describes some of the different behaviour this star has exhibited over the course of the 150 years that the star has been observed.

The note presents some research published by Marsakova and Andronov (Astrophysics 50, No 1, 2007) on variables that display this behaviour. For many of these stars the hump does not appear on every cycle. In the case of R Aur it was on average about every second cycle – in fact 45 out of the 100 cycles analysed. There is a suggestion that there is a correlation between the asymmetry of the light curve and some hump parameters. In the case of R Aur the correlation was quite strong between the asymmetry of the light curve and the phase and duration of the hump.

Some of the explanations that have been given for the hump behaviour are: movement of a shock wave in the stellar atmosphere, resonance between fundamental and overtone periods, or interactions in a circumstellar dust cloud. This is still the subject of debate.

The period of the light curve of R Aur has changed over the years, which is also typical behaviour of the longer period Mira stars. However in this case there does not seem to be a systematic change, rather the period “meanders” between 450 and 465 days. This a good reason to maintain continuous observations of this type of star.

R Aur is a northern hemisphere star so not for observing from here. However the article demonstrates the questions which this type of star elicits. There are some southern hemisphere stars that exhibit similar behaviour e.g. BH Crucis and R Normae.

For more information on stars exhibiting “humps’ and dual maxima go to the document prepared by Frank Shorr on the Long Period Variable (LPV) pages. Also if the Monthly Newsletter is no longer posted on the AAVSO web-site you can find the LPV monthly articles with title “LPV of the month” under the LPV Observing Section. Go to the menu at the top (or the bottom) of the AAVSO Home page, locate “Observing”\subheading “Observing Sections” and locate Long Period Variables. There is a menu on the RH side of the page for LPV of the month.

-- Alan Baldwin

7. Science Can Inform Better Lighting Decisions

Lighting Dunedin smartly will benefit everyone, writes Kyra Xavia. Dunedin has an opportunity to become the first Night Sky City in the southern hemisphere, but the success of this visionary endeavour hinges upon one important factor: night sky-friendly streetlights. Unfortunately, there’s confusion about what’s involved.

Lighting is a complex issue. White LEDs are being heavily promoted for their energy efficiency, they have other costs, which outweigh energy, maintenance and operational savings. The implications are serious because LED technology is rapidly being installed around the world.

White LEDs have broader, long-term losses (caused by the disruptive blue and green wavelengths of light they emit), which include harming the health of human residents, endangering wildlife, and degrading what remains of our night sky, an as yet, untapped asset of immense worth to tourism and our community.

While there’s plenty of scientific evidence about the risks of blue- rich light at night, much public outcry against white LEDs (too bright, harsh, and clinical) and a resulting shift towards warmer light, decision-makers are not yet paying enough attention to, or even aware of a critical factor called scotopic/phototopic (S/P) ratio.

This figure measures how much light emitted from a light fixture is useful to the human eye, and most importantly, for a Night Sky City, how much light pollution is generated. For environmental and ecological impact, the S/P ratio, just like the colour spectrum is crucial — unlike the correlated colour temperature (CCT) of an LED, which only indicates the perceived visual warmth or coolness of light in Kelvin (K).

While both the American Medical Association and the International Dark Skies Association acknowledge the risks of exposure to blue-rich light, neither has yet stated that all white LEDs are problematic. In fact, both still recommend a maximum of 3000K, further confusing municipalities that wish to attain dark sky status.

The New Zealand Transport Agency (NZTA), which sets guidelines for road lighting and design, and co-funds the changeover, has also not yet acknowledged the full range of risks. Nor has Auckland Transport, which has bulk purchasing power and is currently rolling out white LEDs.

As Dunedin city councillors have committed to the Urban Design Protocol, which covers custodianship of the environment and people under its care, they have a responsibility to illuminate Dunedin safely and well. To honour this commitment, new streetlights must not exceed the level of blue and green wavelengths of current streetlights, and they must also have a similar or improved S/P ratio of 0.4 to 0.6.

Sadly, warm white LEDs (2700-3000K) breach both — even when shielded and at the same lumen output as the lights they replace. In fact, with an S/P ratio of 1.3, these LEDs will worsen existing light pollution, doubling what we have now and impacting on areas up to 100km away. We know artificial light at night (ALAN) has negative consequences on wildlife as it impairs biological processes required for health in every species with a dark/light cycle, disrupting too, communication habits, foraging, mating and orientation.

Exposure to blue-rich light also suppresses the production of melatonin (a powerful antioxidant with protective immune, anti-inflammatory, and tumour suppressing activity). For humans, this means an increased risk of Alzheimer’s, cancer, diabetes, depression, obesity and other diseases.

Although people can reduce their exposure to blue-rich light in their own homes, it’s impossible to do so outdoors with white LED street lights. Nor can wildlife and ecosystems escape.

Blue wavelengths of light also scatter in the eye to create a "veiling" effect, resulting in visual discomfort, dangerous disability glare, and noticeably more contrast, which further diminishes night-time vision. (White blue-rich light is perceived as being 3-5 times more glary than orange light — as seen with the blinding headlights on modern cars.) For young people, mature drivers (a large percentage of the population), and those with impaired vision, white LEDs pose an even greater risk. Claims that white blue-rich LEDs improve traffic/pedestrian safety and reduce criminal activity remain unfounded and some recent research contradicts this assumption.

Not only that, the intense light from white LEDs causes the pupil to contract, so while the sky appears darker, the human eye is unable to detect all but the brightest stars. All of which makes white LEDs unsuitable for a Night Sky City. Orange street lighting has been safely used for more than 60 years, and its colour rendition has not been an issue (until the lighting industry’s strong push for white LEDs).

Dunedin can be an enviable star sanctuary by shielding existing lights — and when safer, energy efficient Amber LEDs become more affordable, and once the NZTA (which co-funds street lighting) recognises their worth and updates its guidelines, an intelligent and responsible changeover can be made. As the retrofit will affect the city for decades, lighting Dunedin smartly will benefit everyone.

To learn more, visit www.change.org/p/light-dunedin-smartly.

-- Kyra Xavia is a freelance journalist who has written this piece on behalf of the Dunedin Dark Skies Group. See the original at https://www.odt.co.nz/opinion/science-can-inform-better-lighting-decisions

8. John Glenn

John Glenn, a military vet turned space pioneer, has died at the age of 95.

After flying 59 combat missions in World War II, Glenn became an early recruit into NASA's Mercury program. In 1962, he became the first American astronaut to orbit the Earth. Years later, in 1998, he became the oldest person to fly in space when he joined the STS-95 crew aboard Discovery.

After leaving NASA in 1964, Glenn rejoined the military before being sidelined by an injury in 1965. He then went into the private sector before re-emerging for a 1970 run for the Senate in Ohio. Though he lost the primary, he won a seat in 1974, elected as a Democrat. For a brief period in 1983 and 1984, Glenn was also a presidential candidate but failed to secure any states in the primary contests. He withdrew in March of 1984, remaining in the Senate until 1999.

In recent days, Glenn had been admitted to Ohio State University Wexner Medical Center. His family, including his wife Annie, were by his side when he passed away. Glenn was the last of the Mercury 7 to pass away.

-- By John Wenz of Astronomy magazine, on December 8, forwarded by Roland Idaczyk. See the original at http://www.astronomy.com/news/2016/12/john-glenn-death

9. Icy Ceres

New results from NASA's Dawn orbiter show that Ceres, the largest asteroid, must possess a global layer of water ice that lies just below its dark, dusty surface.

Even before NASA's Dawn spacecraft reached asteroid 1 Ceres in March 2015, planetary scientists knew that this sizable world was not the dry-as-dust object that comes to mind when we imagine what asteroids should be like. For starters, it has a density (2.1 g/cm^3) far too low for a solid ball of silicate rock. Infrared spectra taken as long ago as 1978 revealed the presence of water-infused clay minerals on its surface, and scans by ESA's Herschel space observatory a few years ago even caught Ceres exhaling clouds of water vapour.

But one surprise from Dawn is that, apart from a smattering of bright spots here and there inside craters, there's not a lot of ice actually exposed on the surface. Whatever ice Ceres has must lie deeper down. Now, it turns out, "deeper down" is probably no more than one or two meters, and that water ice must be everywhere. As detailed in this week's Science, the broken-up rubble on Ceres' surface contains high concentrations of hydrogen — and, cosmochemically speaking, water ice is the only likely compound to account for all that hydrogen. In fact the near-surface rocks contain up to 10% water by mass, and this global ice layer likely extends to great depth.

When a high-energy cosmic ray slams into an atom in Ceres’ surface, the target nucleus “explodes,” producing a spray of secondary particles, including neutrons. These particles can collide with other atoms in the regolith, creating gamma rays that escape with other neutrons from the dwarf planet and reach Dawn in orbit.

Dawn's Gamma Ray and Neutron Detector (GRAND) slowly built up maps of neutrons and gamma rays escaping from Ceres as the spacecraft orbited. Importantly, GRAND only detects neutrons and gamma rays within about 1 meter of the surface.

The resulting maps show that the near-surface hydrogen is roughly 100 times more abundant than was found on 4 Vesta, Dawn's previous host, which is largely covered with basaltic rock. On Ceres, the hydrogen signature is very uniform and increases dramatically toward the poles. The team interprets this gradation as a shift from minerals that reacted with (and incorporated) liquid water near the equator to near- surface water ice beginning at latitudes poleward of about 40°. There water ice is probably filling the gaps between fine particles of dust.

This water didn't come from impacting comets but rather must have been present when Ceres formed. Early in solar-system history, this body likely was at least warm, if not hot, due to the kinetic energy of near-constant bombardment and the decay of radioactive elements in its rocky matter, so the interior of Ceres separated into a rocky core surrounded by a less-dense exterior.

It's not clear how far this differentiation progressed. But it's no great leap to imagine that Ceres once had a global ocean (or at least an outer layer of briny mud). Over time, sunlight warmed the equatorial regions enough to drive out the near-surface water and concentrate it at the poles.

Yet exposures of water ice aren't common on the surface. The bright spots in the big crater Occator are likely salt deposits. Dawn's spectra suggest that water exists on the floor of a crater called Oxo and within some (but not all) of hundreds of polar craters that are persistently shadowed. These "cold traps," accumulate water vapour over time that's been driven from Sun-warmed surfaces elsewhere.

So why isn't Ceres icy white all over instead of the very dark surface (only 9% reflective) seen today? Ceres likely came together with a large helping of the kind of carbon-rich rock found in primitive, carbonaceous chondrite meteorites. Every time something blasts into Ceres, it creates a plume of ejected debris that spreads outward and over the surface. It's a mix of carbon-infused dust and water. Some of the water plops back onto the surface and eventually migrates toward the poles. But water vapour is vulnerable — ultraviolet sunlight readily breaks it down into hydrogen and oxygen — and so over time what settles back onto the surface becomes ever more desiccated.

Ceres orbits further from the Sun than Vesta. Ceres's average distance (a) is 2.77 AU (370 million km). Vesta's average distance is 2.36 AU (354 million km). So Vesta gets about 1.4 times more sunshine than Ceres.

-- Mostly abridged from an article by Kelly Beatty on Sky & Telescope's webpage. See the original with pictures and diagrams at http://www.skyandtelescope.com/astronomy-news/ice-is-everywhere-on-ceres/

10. 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 This email address is being protected from spambots. You need JavaScript enabled to view it. or by completing the online application form found at http://rasnz.org.nz/rasnz/membership-application Basic membership for the 2016 year starts at $40 for an ordinary member, which includes an electronic subscription to our journal 'Southern Stars'.

11. 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 This email address is being protected from spambots. You need JavaScript enabled to view it., Nichola van der Aa, 32A Louvain Street, Whakatane 3120.

12. Kingdon-Tomlinson Fund

The RASNZ is responsible for recommending to the trustees of the Kingdon Tomlinson Fund that grants be made for astronomical projects. The grants May be to any person or persons, or organisations, requiring funding for any projects or ventures that promote the progress of astronomy in New Zealand. Applications are now invited for grants from the Kingdon-Tomlinson Fund. The application should reach the Secretary by 1 May 2016. There will be a secondary round of applications later in the year. Full details are set down in the RASNZ By-Laws, Section J.

For an application form contact the RASNZ Executive Secretary, This email address is being protected from spambots. You need JavaScript enabled to view it. Nichola van der Aa, 32A Louvain Street, Whakatane 3120.


National Geographic headline: “2016 Will Be One Second Longer Than Expected". Tweet in response: "Have we not suffered enough.” -- https://www.buzzfeed.com/robinedds/100-tweets-that-made-british-people-piss-themselves-in-2016

“As to the seven deadly sins I deplore Pride, Wrath, Lust, Envy and Greed. Gluttony and Sloth I pretty much plan my day around.” – Robert Brault.

“The wages of sin are death, but by the time taxes are taken out, it's just a sort of tired feeling.” -- Paula Poundstone.

“I'm dreaming of a White Christmas... and when all the White is gone, I will drink all the Red.” -- Thanks to Peter & Janet.

Newsletter editor:

Alan Gilmore Phone: 03 680 6817
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