RASNZ Electronic Newsletter March 2017

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 195

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.

Contents

1. Auckland Observatory's 50 Year Anniversary
2. 2017 Conference - Call for Papers
3. The Solar System in April
4. New Comet Lovejoy
5. Variable Star News
6. TRAPPIST-1's Planets
7. TRAPPIST-1's Radiation Deadly to Its Planets?
8. Audible Meteors Explained?
9. "The Space Between Us"
10. How to Join the RASNZ
11. Kingdon-Tomlinson Fund
12. Newsletter Format
13. Quotes

1. Auckland Observatory's 50 Year Anniversary

The Auckland Astronomical Society?s Observatory was opened on 21 March 1967 at the time of great interest in astronomy arising from the moon landing programme. Stardome will be playing a short birthday presentation as part of its 7:00 pm shows (Wed - Sun) for the last two weeks of March. Also the exhibit area has been revamped, with new displays on historic and forthcoming comments on space exploration.

-- From an article by Sarah Ell (stardome.org.nz) in the NZ Herald Weekend Supplement (11 March 2017, p. 8), passed along by Alan Baldwin.

2. 2017 Conference - Call for Papers

RASNZ Conference paper submissions

As you will know, 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.

There is still space left in the programme for talks and posters. The link to the paper submission form can be found on the RASNZ Conference website www.rasnz.org.nz/Conference or you can email titles/abstracts to me directly at This email address is being protected from spambots. You need JavaScript enabled to view it.. We will continue to accept papers until such time as the programme is full. Please note that you must be registered for the conference to give an oral presentation and papers will be lightly reviewed for suitability before being accepted. Once reviewed, papers will be accepted on a first come first served basis until the programme is full. A full list of accepted titles and abstracts is being maintained on the RASNZ Conference website.

TTSO11 paper submissions

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 are 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.

-- Warwick Kissling, RASNZ Standing Conference Committee.

3. The Solar System in April

NZ reverts to NZST (UT +12 hours) on April 2 at 3am. Consequently dates and times shown are NZST apart for any on April 1.

Sunrise, sunset and twilight times in April

        Times are for Wellington.  They will vary by a few minutes elsewhere in 
NZ.
                  April  1  NZDT                 April 30  NZST
                  morning  evening               morning  evening
       SUN: rise: 7.33am,  set: 7.15pm     rise: 7.04am, set:  5.31pm
Twilights
Civil:    starts: 7.09am, ends: 7.40pm   starts: 6.38am, ends: 5.58pm
Nautical: starts: 6.37am, ends: 8.12pm   starts: 6.05am, ends: 6.30pm
Astro:    starts: 6.04am, ends: 8.44pm   starts: 5.33am, ends: 7.02pm

April PHASES OF THE MOON (times NZST, as shown by GUIDE)

          First quarter: April  4 at  6.40 am (Apr  3,  6:40 UT)
  Full moon:     April 11 at  6.08 pm (06:08 UT)
  Last quarter   April 19 at  4.07 pm (04:07 UT)
  New moon:      April 27 at 12.16 am (Apr 26, 12:16 UT)

The planets in April 2017

Jupiter becomes visible all night so is a brilliant object in the evening sky. Saturn will be to the east by late evening. Mars will be low to the west after sunset setting before the end of astronomical twilight. Venus moves up in the morning sky during April, a brilliant object to the east. Mercury is too close to the Sun to observe all month.

MERCURY is virtually unobservable throughout April. It is at inferior conjunction between Earth and Sun at 5pm on the 20th. At conjunction the planet will pass 1.5° north of the Sun as "seen" from the Earth. Mercury will be 86 million km from the Earth and 64.4 million km from the Sun.

On the 1st Mercury, in the evening sky, will set only 30 minutes after the Sun. On the 30th, in the morning sky, it rises about 80 minutes before the Sun but at magnitude 2.6 is not likely to be visible due to twilight.

VENUS is a morning object in April. On the 1st it will rise some 45 minutes before the Sun, by the 30th it will rise more than 3 hours earlier than the Sun.

The planet will not be readily visible on April 1 when it is only 12° from the Sun. Its distance from the Sun increases steadily throughout April, particularly early in the month as Venus moves to the west through the stars, away from the easterly moving Sun. This will make it an easy object within a few days. It will be visible a little to the north of east at first shortly before sunrise.

Venus is in Pisces all month and is stationary on April 13 after which it will start moving to the east but less rapidly than the Sun. The position of the planet relative to the stars will change little during the month

The morning of the 24th will find the crescent moon some 4.5° to the upper right of Venus

MARS will remain a low early evening object during April. On the 1st it sets just over 80 minutes after the Sun, dropping only slightly to 75 minutes later on the 30th. It will be low, with a magnitude 1.5, visible only briefly as the sky darkens following sunset. Mars will set a little before the end of Astronomical twilight so not be an easy object.

During April, the planet moves to the east through Aries and on into Taurus on the 12th. On the 21st and 22nd it will be 3.5° above the Pleiades, by the end of April Mars will be 7° below the similarly coloured star Aldebaran. On the 28th the moon, a very thin crescent less than 5% lit, will be 5° to the upper left of Mars.

JUPITER is at opposition on April 8, NZ time. At opposition Jupiter will be 4.5 AU, 666 million km from the Earth and a further 150 million km from the Sun. The planet will be in Virgo moving in a retrograde sense to the west as the Earth overtakes it. Jupiter starts the month just over 6° from Spica, its slow westerly motion taking it to nearly 9.5° from the star on the 30th.

The full moon will be 6.5° from Jupiter on the evening of April 11, the moon at the apex of an inverted triangle formed by it, Jupiter and Spica.

SATURN will rise close to 11 pm NZDT 1st of April, which becomes 10pm NZST on the 3rd with the time of rise advancing to just after 8 pm by the 30th. Thus it becomes a prominent later evening object to the east at magnitude 0.3 to the east during the month. It will, of course, be readily visible in the morning sky. By the end of April Saturn will be highest and due north about 3.40 am.

Saturn is stationary on the 6th, after which it will start moving to the west, but its position in Sagittarius will change little throughout the month.

The 75% lit waning moon will be 3.5° to the lower right of Saturn on the morning of April 17, with the two closest at about 6 am.

Outer Planets

URANUS is at conjunction with the Sun on April 14. Hence it will be too close to the Sun to observe throughout April.

NEPTUNE, in the morning sky, rises about two and a half hours before the Sun on the 1st and nearly 5 hours earlier on the 30th. The planet is in Aquarius at magnitude 8.

PLUTO, magnitude 14.4, is in the morning sky rising about 12.40 am, NZDT, on the 1st and 9.45 pm on the 30th. It will remain in Sagittarius just under 2.5° from the 2.9 magnitude star pi Sgr.

Minor Planets

(1) CERES is an early evening object, brightening slightly from magnitude 9.1 to 8.9 during the month. It is quite close to Mars moving on a path almost parallel to the major planet which overtakes Ceres during the month. On the 1st they are 4° apart with Ceres above Mars. On the 8th they are at their closest, 3° apart. By the 30th Ceres is will be dropping behind Mars, the two then being 5° apart.

On the 12th both Ceres and Mars move from Aries to Taurus, with Ceres crossing the border shortly before Mars.

(4) VESTA, an evening object in April, is in Gemini. It passes Pollux, magnitude 1.2, early in April, the two being closest on April 7, just over 2° apart. The asteroid moves on into Cancer on the 24th. Vesta dims slightly during the month from magnitude 7.7 to 8.0. It sets about 12.45 am, NZDT, on the 1st and just before 10.30 pm, NZST, on the 30th.

-- Brian Loader

4. New Comet Lovejoy

Terry Lovejoy of Brisbane found another comet -- his sixth! -- on March 10. His posting to the Comet Watch Facebook group follows:

"Thank you everyone for your kind words, and of course to the people that sacrifice their spare time to get out there and do follow up observations on new comets like this.

The latest comet, C/2017 E4, was found on a set of 3 images made on the morning of March 10 (Local time) in the constellation of Sagittarius. Although my 6th discovery, this was the first discovery with the Hyperstar 14" Celestron Schmidt Cassegrain telescope. However, because the field of view is now smaller I must now make shorter exposures, and more of them, to cover similar amounts of sky as possible. However, I felt the extra aperture have has more than compensated especially since my location experiences quite bad light pollution being just 18 km from the centre of Brisbane, a city of more than 2 million people.

Back to the comet, it was found using MOD (Moving Object Detection) a computer program I wrote that searches sets of images for moving objects like comets of asteroids. I tend to run MOD with very high sensitivity, which means it will identify anything remotely resembling a moving object, resulting in mostly false positive detection's. In fact in crowded star-fields this can be as high as 90% false positives and so I must examine each detection manually. Nevertheless, this is huge time saver compared to examining the entire image manually. That morning a lot of the fields were in the milky way I had a large number of false detection's I had to examine, and there were also at least a dozen asteroids, but finally there was one object that had a definite coma and I knew almost certainly a comet. I then did some checks against known asteroids/comets plus some checks to eliminate internal optical reflections as a cause for the detection. This all checked out so I was certain of a new comet at this point.

I then sought independent confirmation from another observer, and looking at Messenger I could see Cristavao Jacques in Brazil was online, so I contacted him, but unfortunately dawn had started and he had closed up the observatory so there was no luck there. I then contacted Michael Mattiazzo and he was able to get a confirmation image not long after from a remote telescope in New Mexico. This was all well within the 24 hours of the actual discovery images, which is probably a record for me! The comet was then posted on the Possible Comet Confirmation Page and astrometry started to stream in over the next few days and within 3 days the orbit was known with enough certainty for it to be designated as C/2017 E4. The orbit indicates - unfortunately - this is an intrinsically small comet that probably stay quite faint (and it could even disappear altogether) but we can always hope for a better display."

---------- C/2017 E4 (Lovejoy) is in the morning sky, moving north-east, so getting closer to the sun. On March 20 it will be 108 million km from Earth and 138 million km from the Sun. It will be closest to the Earth, 91 million km away, on March 31. It passes 74 million km from the Sun on April 23. -- Ed.

5. Variable Star News

AAVSO Announcements ---------- The American Association of Variable Star Observers Annual Report for 2015-2016 has been released online. It is available at https://www.aavso.org/annual-report in both a high-resolution and a low-resolution version. There is useful information on AAVSO programmes contained within this document.

Stella Kafka, AAVSO director, has announced that Dr Bert Pablo will be joining the AAVSO as the new Staff Astronomer. He will start in July. Bert received his Astronomy PhD from Iowa State University, and then joined the BRITE-Constellation collaboration at the University of Montreal. His research has been on ?Heartbeat stars?. (Refer article on Iota Orionis below). You can find more information about Bert at: https://www.aavso.org/bert-pablo

This information was taken from the AAVSO (monthly) Communication ? March 2017.

Eclipsing Binary Stars ----------

Iota Orionis and the BRITE Constellation Project

Iota Orionis is a binary star system and is easily visible with the naked eye, being the brightest star in Orion?s sword in the constellation of Orion. The light from Iota Orionis is relatively stable 90 per cent of the time, but then dips rapidly followed by a large spike; a repeating one-per-cent spike in the light. Stars with this type of variation have been labelled Heartbeat stars due to the similarity of the variation to electrocardiogram rhythms. This unusual variation is the result of the interaction of two stars in a highly elliptical 30-day orbit around each other. The observations were made using the world?s smallest astronomical space satellites, referred to as ?nanosats?; there are five being used in the BRITE (BRIght Target Explorer)-Constellation program.

Iota Orionis represents the first time this effect has been seen in such a massive system (35 times the mass of the Sun), an order of magnitude larger than any in previously known systems, and the binary system allows for direct determination of the masses and radii of the components. On close approach gravitational forces distort the shape of the stars and trigger quakes in the star, allowing us to probe the star?s inner workings, just as we do for the Earth?s interior during Earthquakes. The phenomenon of quakes is very rare in massive stars in general and this is the first time induced quakes have ever been seen in a star this massive.

-- Abstracted from an AAVSO web-site News Article. For further information on BRITE go to http://www.brite-constellation.at/. An article on Iota Orionis was published in Monthly Notices of the Royal Astronomical Society, (Oxford University Press), http://doi.org/10.1093/mnras/stx207 February 9, 2017.

Analysis of Binary Stars ----------

One of the major projects of Variable Stars South since its inception has been the monitoring of binary stars visible in the Southern hemisphere, analysis of the light curves and deduction of the unique properties of the individual star systems. The light curves of binaries can be used to deduce the orbital elements, relative sizes and other properties of the stars in the system.

In the Variable Stars South Newsletters (website Tab Community, Heading Newsletters) Tom Richards has been writing about techniques for dong initial analysis and giving tips on things to watch out for in fitting models. The first article appeared in the 2016-3 (July) issue. (pp 24 ? 27) Reading the clues in light curves of eclipsing binaries Part I ? Finding star sizes. The subsequent article, Part II ? Interpreting eclipse depths appeared in the 2016 October issue. The articles use bold, clear diagrams to illustrate the systems.

?The techniques reveal how eclipse widths in light curves can tell us if the stars are close or well separated. We saw that relative depths tell us relative brightnesses and absolute depths give us strong clues about how complete the partial eclipses are. In the case of total eclipses, we saw further that we can derive the relative luminosities from the relative depths, and hence by combining luminosity and brightness, get the relative radii. We derived all those features of the eclipsing system by thinking qualitatively about the geometry?.

This information can be derived by logical reasoning and very simple arithmetic. Getting such results is an invaluable check on any astrophysical modelling you might go on to perform

The third in the series of articles, Part III ? The strange case of V477 Lyrae, was in the recently issued 2017 January issue. This star has an unusual light curve (the volcano shape) and the article shows an application of analysis to a complex, late evolutionary, system. The binary V477 Lyrae exists in a planetary nebula and is thus a star that has suffered mass loss to the planetary nebula, as well as mass being transferred from the secondary star to the primary.

The next article in the series will discuss investigating the colours and temperatures of the component stars.

-- Alan Baldwin

6. TRAPPIST-1's Planets

The star TRAPPIST-1 is an unassuming, M8 red dwarf star. It lies 39 light-years away in the constellation Aquarius. With a diameter only one-tenth that of our star, the dwarf puts out less than a thousandth as much light as the Sun.

Last year, Michaël Gillon (University of Liège, Belgium) and colleagues announced that a trio of small exoplanets orbits this small star (although the third world was of dubious reality). Now, after an intensive follow-up campaign, the team has discovered that there are actually seven planets, not three. All are likely rocky. Three lie in TRAPPIST-1?s putative habitable zone ? the region where, given an Earth-like composition, liquid water could be stable on the surface. But all, with enough hand-waving, might have a chance at liquid water.

The astronomers detected the exoplanets using the transit technique, which catches the tiny dip in starlight when a planet passes in front of its host star from our perspective. The discovery sequence began when the team found that what it had thought was a combined transit of planets #2 and #3 was in fact the crossing of three planets. The observers next studied TRAPPIST-1 with an impressive array of ground-based observations. But the big breakthrough came with the Spitzer Space Telescope which observed the star for 20 days. It saw 34 clear transits. The team was then able to combine their ground- and space-based observations to determine that the signals likely came from seven different planets.

Only six of those are firm detections, however. Number 7, or planet h, is iffy in its specs: The team only detected a single transit for it, and astronomers prefer to see three transits before calling something a candidate planet. Expect astronomers to haggle over this one in months ahead.

All of the seven exoplanets discovered around TRAPPIST-1 orbit much closer to their star than Mercury does to the Sun. But because TRAPPIST-1 is far fainter than the Sun, the worlds are exposed to similar levels of radiation as Venus, Earth, and Mars.

The orbital periods of the inner six planets range from 1.5 to 12 Earth days, with the period of outermost h being anywhere between 14 to 35 days. The smallest two worlds are about three-fourths as wide as Earth, the largest 10% wider. The biggest orbit is less than 20% as large as Mercury?s.

One of the wonderful things about this system is that the exoplanets? orbits are resonant with one another. This means that their orbital periods are rough integer multiples of one another. For example, in the same span of time that the innermost planet whips around the star eight times, the second planet takes five laps, the third three, and the fourth two. This setup gravitationally links the planets together and can lead to tiny shifts in their positions. Based on these shifts, the team could calculate the planets? gravitational influences on one another, and hence their approximate masses and densities. All are consistent with being rocky, the team concludes in the February 23rd Nature.

Such resonant orbits arise when worlds migrate from their original locations, Gillon explains. Astronomers think that when lightweight planets form far out in a star?s planet-forming gaseous disk, gas drag and such will make them advance inward. During this inbound migration, the worlds catch one another in resonant orbits, such that they can form a kind of ?chain of planets,? he says. In this case, the migration landed the exoplanets in what the team calls the ?temperate zone? ? orbits with enough incoming starlight that, with the right conditions, the planets might at least sometimes have liquid surface water. It?s a looser definition than that for ?habitable zone.?

The planets are also all likely tidally locked with their star, meaning they always point the same hemisphere at it, as the Moon does to Earth. So close to the star, the planets could experience huge tidal pulls, stretching and squeezing their interiors and spurring heating and even volcanism, similar to what we see on Jupiter?s Galilean moons.

TRAPPIST-1 is quiet for an M dwarf ? notably less active that Proxima Centauri, which also has a habitable-zone planet (although it?s likely a desert world). But unfortunately, astronomers don?t know how old the star is. It?s also unclear whether the planets? orbits are stable: The researchers haven?t determined the seventh planet?s orbit, nor do they know if there are other worlds in the system mucking things up. This kind of star, called an ultra-cool dwarf, is very common; roughly 15% of stars in the nearby galaxy fall into this category, Guillon estimates. Ultra-cool dwarfs live for trillions of years.

Read more about the result in the European Southern Observatory?s press release at https://www.eso.org/public/news/eso1706/

References: M. Gullion et al. ?Seven temperate terrestrial planets around the nearby ultracool drwarf star TRAPPIST-1.? Nature. February 23, 2017. Ignas Snellen. ?Earth?s Seven Sisters.? (editorial) Nature. February 23, 2017.

-- Abridged from an article by Camille M. Carlisle on Sky & Telescope's webpage at http://www.skyandtelescope.com/astronomy-news/dim-star-has-seven-earth-size-planets-2202201723/

7. TRAPPIST-1's Radiation Deadly to Its Planets?

The star with seven exoplanets puts out enough high-energy radiation to tear away the inner planets? atmospheres in a few billion years.

As part of the ongoing interest in this small sun, Vincent Bourrier (University of Geneva Observatory, Switzerland) and colleagues are putting together a picture of how much high-energy radiation streams out from the star, and what that radiation might mean for the planets.

The team used the Hubble Space Telescope to study the star?s ultraviolet output. Specifically, they looked at Lyman-alpha emission, which is a particular wavelength emitted by hydrogen atoms and comes from the star?s chromosphere, the layer between the stellar ?surface? (the photosphere) and the intensely hot, ionized, wispy corona. The team found that TRAPPIST-1 emits less than half as much Lyman-alpha radiation as other cool, exoplanet-hosting M dwarfs ? including Proxima Centauri, which radiates six times more in ultraviolet as TRAPPIST-1 does. That?s to be expected, since TRAPPIST-1 is also cooler than the other M dwarfs are.

However, last year the team also found that TRAPPIST-1 emits about as much in X-rays as Proxima Centauri. These X-rays come from the stars? coronas. The ratio of X-rays to ultraviolet is interesting for a couple of reasons. First, X-ray and ultraviolet output decrease with time for these stars, but X-rays drop off much faster. The fact that TRAPPIST-1 emits roughly a third as much energy in Lyman-alpha as it does in X-ray suggests that the star is ?relatively young,? the team posits in their March 2017 Astronomy & Astrophysics article.

What ?relatively young? means is an open question. Astronomers know the star is at least 500 million years old, because it has ?settled? into being an adult star. Beyond that, it?s anyone?s guess. Jeffrey Linsky (University of Colorado, Boulder), who has worked extensively on M dwarfs and the trends in Lyman-alpha and X-ray emission for different types of stars, says that TRAPPIST-1 seems both old and young. Stars are born spinning quickly, then slow as they age. TRAPPIST-1 rotates in 1½ days, which at face value would point to it being young, he says ? but astronomers don?t know how fast these ultra-cool dwarfs spin down. Furthermore, the star?s fast motion through space usually would indicate it?s a member of the old stellar population that comprises the galaxy?s halo, but that May be a fluke.

Bourrier agrees that the age question is currently unanswerable. The ratio of X-ray to ultraviolet emission seems to indicate that TRAPPIST- 1 is ?not extremely old,? he says, ?but I do not think that at this point we can say much more than this.?

The second reason the X-ray and ultraviolet levels matter is for habitability, a possibility which has received perhaps more attention than it deserves. Although the ultraviolet level is low, the radiation overall is still high enough that it could strip an Earth-like atmosphere from the inner two planets, b and c, in 1 to 3 billion years; for the planets d, e, f, and g (e, f, and g are in the putative habitable zone), the process would take anywhere from 5 to 22 billion years. The team does see a hint of atmospheric escape from b and c, although the slight drop in starlight that implies it might instead be due to coronal variability.

Reference: V. Bourrier et al. ?Reconnaissance of the TRAPPIST-1 exoplanet system in the Lyman-alpha line.? Astronomy & Astrophysics. March 2017.

-- Abridged from an article by Camille M. Carlisle on Sky & Telescope's website at http://www.skyandtelescope.com/astronomy-news/seven-planet-star-ageless-maybe-deadly-0603201723/

8. Audible Meteors Explained?

The astronomical literature is dotted with reports of observers hearing bright meteors that seem to hiss, pop, or ping. Now, a recent study in Nature: Scientific Reports out of Sandia National Laboratories suggests a possible cause.

Most of the meteors you see at night are tiny dust grains, burning up as they streak through Earth's upper atmosphere at speeds up to 70 km/s. Once in a great while, something really big, say, golf-ball-size or larger comes in, burning up in a brilliant fireball display. (A fireball is a meteor brighter than ?4 magnitude (as bright as Venus), and a bolide is a fireball with a bright terminal flash at the end of its trail.

Sometimes observers report hearing a distinct hiss or crackle accompanying many bright fireballs simultaneously with the bright flash. But the trouble with hearing concurrent sounds with meteors has always been the distance involved. Not only do meteors occur in the tenuous upper atmosphere, which is a poor propagator of sound, but they're also distant, occurring in the mesosphere about 75 to 100 km up. Think of lightning: how you always see the flash several seconds before the booming thunder arrives.

And yet reports of audible meteors persist. The Sandia study proposes that strong millisecond-long flashes recorded in bright fireballs are intense enough to induce radiative heating in dielectric materials such as dry leaves, clothing, or even hair in the vicinity of the observer, via what's called the photoacoustic effect. The irradiated surfaces heat the air next to them, producing tiny pressure oscillations ? in other words, sound. The study shows that a bolide around ?12 in magnitude (about half as bright as a full Moon) can induce an audible sound in dielectric material of around 25 decibels, loud enough to be heard. For context, a whisper is 10 to 20 decibels, on the lower threshold of what is barely audible. The study even suggests frizzy hair might be an even more effective transducer of the photoacoustic effect.

"It seems significant that people with frizzy hair are reported to be more likely to hear concurrent sound from meteors," the study notes. "Intuitively, frizzy hair should be a good transducer for two reasons. Hair near the ears will create localized sound pressure, so it is likely to be heard. Also, hair has a large surface-to-volume ratio, which maximizes sound creation.

The study notes that strong millisecond flashes were seen in virtually all of the bright bolide meteors documented by the Czech Fireball Network. One particularly brilliant ?15-magnitude fireball named EN091214 was recorded by the network in the early evening of December 9, 2014. Careful analysis of its rapidly changing intensity showed brief flares occurring dozens of times per second, and several witnesses in the vicinity heard sound at the same time. Calculations in the study suggest that the fireball's intense, rapidly varying light should have produced a sound level of 27 ± 3 decibels, consistent with ear-witness accounts.

Over the years, audible meteors have been explained as simply a psychological phenomenon, or perhaps a locally produced effect set up by low-frequency waves and a phenomenon known as electrophonic sound. Edmond Halley collected eyewitness accounts of a bright fireball seen over England on the night of March 19, 1718, which many witnessed claimed ?hiss(ed) as it went along, as if it had been very near at hand,? a claim dismissed by Halley himself.

-- Adapted from an article by David Dickinson on Sky & Telescope's webpage at http://www.skyandtelescope.com/astronomy-blogs/astronomy-space-david-dickinson/new-take-on-audible-meteor-mystery/

9. "The Space Between Us"

Jim Scotti posted the following critique/review on Facebook:

So we saw the movie "The Space Between Us" last night and while I enjoyed the film, it's clear that the director and writer weren't paying attention in their "Rocket Science" class. Here are a few issues (I don't think there are any real spoilers here). I didn't recognize a single star field. We apparently have developed subspace radio providing instant communication between Mars and Earth. As the spaceship approaches Earth (or Mars for that matter) the rocket engines are firing in the direction pushing toward the planet instead of pushing away from the planet to decelerate into orbit around the planet. You could see lots of stars when panning across a scene with daytime sunlit Earth or Mars in the scene. The Dream Chaser spacecraft can take off from a runway without a huge rocket to boost it and fire its rockets to achieve orbit (or at least to go suborbital for getting zero-G for a long time). We apparently need an SLS rocket to launch a 6 person crew into low Earth orbit on a Red Dragon spacecraft to rendezvous with our Mars transport spacecraft. While rocket engines are firing during the journey to/from Mars, the crew enjoys zero-G while floating around the cabin. And the trip to/from Mars still takes 7 months despite the continuous rocket firing. Did I mention that I enjoyed the movie in spite of the science flaws?

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. 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 2017. 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.

12. Newsletter Format

Distribution of the past three Newsletters has been via MailChimp. This allows readers to unsubscribe automatically, a legislative requirement.

This issue is being sent in HTML format. That allows reading on any computer or mobile device. Comments on the usefulness, or otherwise, of this change are welcomed. -- Ed.

13. Quotes

"Okay - Other than giving us cars, planes, spaceships, cell phones, the internet, life-saving medicine, a dramatically increased life span, valuable warnings and guidance, a fundamental understanding of how our world works and Jurassic Park - what has science done for us?" -- https://www.facebook.com/EndTheWoo/photos/

"Life is like a roll of toilet paper; the closer you get to the end of the roll, the faster it goes." -- Anon. Quoted in The Economist letters, March 4, 2017, p. 12.

Newsletter editor:

Alan Gilmore Phone: 03 680 6817
P.O. Box 57 Email: This email address is being protected from spambots. You need JavaScript enabled to view it.
Lake Tekapo 7945
New Zealand