Te Patiki – Palmerston North Astronomical Society Inc September 2010
September 2010 September
Headliners The NEXT MEETING Spring on Titan brings will be at the Manawatu sunshine and patchy Observatory on Wednes- clouds day, September 29th, http://www.astronomy.com/asy/ at 8.00 p.m. default.aspx?c=a&id=10253 Jupiter’s Disappearing Belt Many of you who have http:// read Te Patiki over the www.oneminuteastronomer.com/2 010/09/09/jupiters-disappearing- years will no doubt realize belt/ that many of our members Possibility for White Dwarf specialize in deep-sky pho- Pulsars? http:// tography and are amongst www.universetoday.com/74300/ New Zealand’s leading white-dwarf-pulsars/ proponents of this field of In this issue: astronomy. The Big Wet before the Big Dry? There are however more The Planet Mercury has a strings to our bow than comet-like tail. astrophotography as you Google finds a new impact crater in Egypt will find out when you come along and listen to Weird water lurking inside giant planets our featured talk by one of our newer members, Awesome death spiral of a bizarre star Carl Knight, who now Above: Carl Knight with his pride and joy, a 12 lives on the rise just NW NASA to Send a Probe Into inch (30cm) Meade Cassegrain set up outside our the Sun of Bulls. observatory last year for an open night. Carl has Ancient Greeks spotted Hal- ley's comet since established himself at a dark sky site on the Carl will be speaking to us Mars moon may have rise north of Bulls heading towards Wanganui. formed like our own about his journey into, ―Variable Star Observ- The Beauty of a Barred Spi- ral ing.” The talk will cover curve – Visual, CCD meas- We hope to have another the HR Diagram and stellar The star photographers who urements and a visual frac- member’s talk about their captured the night sky evolution, types of variable tional estimation exercise. particular passion in as- stars and where they fit Earthquake Damages Some Organising your VS ob- tronomy soon. into the evolutionary pro- Canterbury Observatories serving – preparation and Ian Cooper. What’s The Use of Astrono- cess. UW Trianguli—an charts. Contact numbers my? international flap. A case Variable Star organisations. Most Massive Star Found (So study in international co- Variables to observe and President: Ian Cooper 329 7829 Far) operation. report on for next month. Secretary: Peter Wilde 358 4857 Light curves and what they Treasurer: George Ionas 358 7007 tell us. Getting the light Editor: Jeremy Moss 359 4498
Te Patiki – Palmerston North Astronomical Society Inc September 2010 THE BIG WET BEFORE THE BIG DRY?
If you think that this rain we have been Palmerston North’s 10 most sunniest above list, but only just! This is not be- yond possibility with the advent of La having lately is a little over the top then years ranked. Niña starting during this spring. A La you aren’t mistaken! From the time of Niña phase of the S.O.I. (Southern Os- writing (and there is still 4.5 days left in cillation Index) is usually beneficial to September, this month is the 5th wet- Rank Year Sunshine Hours astronomers in the Manawatu region. test since records for Palmerston 1 1935 2013 North began in June 1928. There is still 2 1947 2003 On the following page I have included a a chance that this month may move up graph of the S.O.I. produced from Dar- the list, unfortunately. 3 1933 1982 win in the Northern Territory of Aus- tralia (originally called Palmerston by 4 1974 1972 the way). I have highlighted a number of 5 1950 1967 years that show up in the lists on this Below is a list of the wettest recorded page for interest and easier identifica- months for Palmerston North: 6 1948 1962 tion. 7 2003 1960 I started into active astronomy at the Rank Month/Year mm of rain 8 2008 1958 end of 1973. As can be seen from the 1 Feb 2004 303.4 9 2000 1951 graph this was the end of a deep El Ni- ño period. That spring was a typically 2 Jun 1947 265.1 10 1934 1948 nasty El Niño style spring, but fortu- 3 Jan 1953 247.2 nately there was an abrupt change to La Niña conditions in early January 4 Jul 1974 245.2 As far as sunshine is concerned 2010 is 1974 (the month I brought my first 5 Sep 2010 227.8 not a contender for the list above but telescope. Talk about timing Trev!) more likely it could be in the top 10 6 Oct 1935 224.9 cloudiest of years as measured by sun- As a rule of thumb my best years in 7 May 1948 224.1 shine totals. astronomy all feature above the line on the graph, i.e. they are during La Niña 8 Dec 1966 221.0 periods of the S.O.I. We are currently 9 Mar 1965 218.5 The 10 cloudiest years on record are; heading to a moderate to strong La Niña phase so don’t be surprised if the 10 Jun 1935 211.5 Rank Year Sunshine Hours weather patterns also change soon. Here is hoping any way. 1 1992 1341
Some more intersting facts that emerge 2 1980 1397 Some Background. from the meta data. 1935 features 3 1983 1432 twice on the list above so it is no sur- Why are "El-Niño" and prise that it is 2nd on the list for wet- 4 1979 1524 "La-Niña" so named? test years with a total of 1,351.9mm. 5 1942 1531 "El-Niño" is named after a Peruvian First on the list is also no surprise, 6 1991 1569 Christmas festival where the warming 2004 with 1,376mm. of the waters off Peru is said to occur 7 1953 1588 near the birthday of "The Boy" (El Ni- It is also intersting to note that no 8 1981 1608 ño), or the Christ child. Meteorologists years in the decades of the 1980’s thus named the phenomenon the "El- through the 1990’s (i.e. 1981-2000) had 9 1976 1628 Niño Southern Oscillation", or ENSO any months where the rainfall exceeded for short. The reverse phenomenon, 10 1929 1636 the cooling of the eastern Pacific wa- 200mm! ters, was at first called "Anti-El-Niño",
It is very interesting to note that where until it was realised that this literally 2010 currently sits at 1,191 hours with 1935 really surprises is that it is top of meant the Anti-Christ ! To avoid this just on three months left. We would unfortunate connotation, it was re- our most sunniest of years too! need the next three months to average named "La-Niña" (or "The Girl"). around 150 hours each to avoid the
Te Patiki – Palmerston North Astronomical Society Inc September 2010
Above: The La Niña years are the peaks above the zero line shown in blue, whilst the El Niño periods are the spikes below the line and shown in red
The ENSO (El Niño Southern Oscilla- Yes it has been bad so far this year, but back at you. tion Index) is one of the main climate if we can get over this low of unfavour- drivers on the planet. Others include able conditions then we should all be the AMO (Atlantic Multidecadal Oscil- raring to go when the conditions are Ian Cooper. lation) which has a 60 year cycle that better soon. There is not better sight strongly mirrors global climate varia- for sore eyes than to see another tired tion. astronomer with eyelids half open and a satisfied grin on their face beaming Ostensibly the coming La Niña period Below: Out here in the New Lake District (temporarily anyway) widespread surface is expected to bring wetter weather to flooding was the order of the day. These paddocks on Main Drain Road were typical. the east coast of mainly the North Is- land but also to the South Island as well. Anti cyclones, or ‘highs,’ are ex- pected to lie to the centre or south of Cook Strait and therefore there is like- ly to be a predominance of winds from the eastern and southern quarters over central New Zealand.
For west coasters on the L.N.I. (Lower North Island) and the South Island too this will mean drier, sunnier conditions (ergo, clearer night skies as well) should prevail based upon past experi- ence.
Te Patiki – Palmerston North Astronomical Society Inc September 2010 The planet Mercury has a comet like tail
Posted on September 22, 2010 by Anthony ROME and BOSTON – Scientists from meeting in Rome, Italy this week.
Watts Boston University’s Center for Space
Physics reported today that NASA sat- The STEREO mission has two space- http://wattsupwiththat.com/2010/09/22/the- planet-mercury-has-a-comet-like-tail/#more- ellites designed to view the escaping craft, in orbits just inside and outside 25201 atmosphere of the Sun have also rec- the earth’s orbit around the Sun, and
Via Eurekalert: Mercury found to orded evidence of gas escaping from thus increasingly ahead and behind the have comet-like appearance by the planet Mercury. The scientists re- earth (STEREO, or Solar TErrestrial satellites looking at sun ported these findings at the European RElations Observatory, is the third
Planetary Science Congress (EPSC) mission in NASA’s Solar Terrestrial
Probes program). This configuration
offers multi-directional views of the
electrons and ions that make up the
escaping solar wind. On occasion, the
planet Mercury appears in the field of
view of one or both satellites. In addi-
tion to its appearance as a bright disk
of reflected sunlight, a ―tail‖ of emis-
sion can be seen in some of the images.
The announcement of this new method
of observing Mercury and possible ex-
planations for the nature of the gases
that make up this tail were presented
today at the EPSC.
This is an image of Mercury's tail obtained from combining a full day of data It has been known that Mercury exhib- from a camera aboard the STEREO-A spacecraft. The reflected sunlight off its comet-like features, with a coma of the planet's surface results in a type of over-exposure that causes Mercury to tenuous gas surrounding the planet appear much larger than its actual size. The tail-like structure extending anti- and a very long tail extending in the sunward from the planet is visible over several days and spans an angular anti-sunward direction. From Earth, size exceeding that of a full Moon in the night sky. Credit: NASA/STEREO observations of both of these features
Te Patiki – Palmerston North Astronomical Society Inc September 2010 can be done using light from sodium so interesting is that the brightness the Boston University group on refin- gas sputtered off the surface of Mercu- levels seem to be too strong to be from ing brightness calibration methods and ry. The Sun’s radiation pressure then sodium,‖ commented Schmidt, lead determining the precise wavelengths of pushes many of the sodium atoms in author on the paper presented at EPSC. light that would get through the camer- the anti-solar direction creating a tail Of special interest is the way the tail as’ filters. that extends many hundreds of times was spotted in the STEREO data by Ian the physical size of Mercury. ―We have Musgrave, a medical researcher in Aus- ―The combination of our ground-based observed this extended sodium tail to tralia who has a strong interest in as- data with the new STEREO data is an great distances using our telescope at tronomy. Viewing the on-line database exciting way to learn as much as possi- the McDonald Observatory in Texas,‖ of STEREO images and movies, Dr. ble about the sources and fates of gases
Boston University graduate student Musgrave recognized the tail and sent escaping from Mercury,‖ said Michael
Carl Schmidt explained, ―and now the news of it to Boston asking the BU Mendillo, professor of astronomy at tail can also be seen from satellites near team to compare it with their observa- Boston University and director of the
Earth.‖ Much closer to Mercury, sever- tions. ―A joint study was started and Imaging Science Lab where the work is al smaller tails composed of other gas- now we have found several cases, with being done. ―This is precisely the type es, both neutral and ionized, were detections by both STEREO satellites,‖ of research that makes for a terrific found by NASA’s MESSENGER satel- explained Jeffrey Baumgartner, senior Ph.D. dissertation,‖ Mendillo added. lite as it flew by Mercury in its long ap- research associate in the Center for proach to entering into a stable orbit Space Physics at Boston University. Research in Boston University’s Center there. Baumgartner designed of the optical for Space Physics involves interdiscipli-
instruments that discovered the excep- nary projects between members of the
―What makes the STEREO detections tionally long sodium tail. Astronomy Department in the College
of Arts and Sciences and faculty, staff
The current focus of the team is to sort and students in the College of Engi-
out all of the possibilities for the gases neering. Research areas include obser-
that make up the tail. Christopher Da- vational and theoretical studies in at-
This is a schematic representation of the vis, a researcher at the Rutherford Ap- mospheric, ionospheric and magneto- viewing geometry that allows the STE- pleton Laboratory in Chilton, England spheric physics, planetary and come-
REO camera systems to make observa- and member of the STEREO team re- tary atmospheres, solar and helio- tions of Mercury's tail. Credit: Boston sponsible for the camera systems on spheric physics, and space weather.
University Center for Space Physics both satellites, is working closely with
Te Patiki – Palmerston North Astronomical Society Inc September 2010 Google Earth leads to spectacular meteor crater find
Posted on September 24, 2010 by Anthony 2008 Google Earth search led to the plume that would have been visible
Watts discovery of Kamil crater, one of the over 1000 km away, and drilled a hole
best-preserved meteorite impact sites 16 m deep and 45 m wide into the http:wattsupwiththat.com/2010/09/24/ ever found. Earlier this year, a gritty, rocky terrain. Since then, the crater google-earth-leads-to-spectacular-meteor- sand-blown expedition reached the site had sat undisturbed by Earth’s geolog- crater-find/#more-25304 deep in the Egyptian desert to collect ic and climatic processes, which usual- From the European Space Agency via iron debris and determine the crater’s ly render all but the very largest terres- press release, the modern meteorite age and origins. One day within the trial impact craters invisible. It was enthusiast’s dream – finding a crater last several thousand years, a rare me- also, as far as is recorded, unseen by on Google Earth and seeing it through tallic meteorite traveling over 12 000 humans. to full discovery. As more and more hi- km/hour smashed into Earth’s surface res images find their way in Google near what is today the trackless border Searching for craters in Google Earth, we will likely see more discover- region between Egypt, Sudan and Lib- Earth But that changed in 2008, ies like this. Egyptian desert expe- ya. The impact of the 1.3 m, 10-tonne when the crater was spotted during a dition confirms spectacular me- chunk of iron generated a fireball and Google Earth study conducted by min- teorite impact 23 September 2010 eralologist Vincenzo De Michele, then A with the Civico Museo di Storia Natu-
rale in Milan, Italy. He was searching
for natural features, when by chance
he saw the rounded impact crater on
his PC screen. De Michele contacted an
astrophysicist, Dr Mario Di Martino, at
the INAF (National Institute for Astro-
physics) observatory in Turin, who,
together with Dr Luigi Folco, of Siena’s
Museo Nazionale dell’Antartide, or-
ganised an expedition to the site in
Kamil crater seen by satellite (small round dot near centre of image) A radar February this year. It took over a year image of the Kamil crater provided by the COSMO-SkyMed satellite constel- to plan and obtain permissions for the lation of the Italian Space Agency (ASI). Credits: ASI 2009 journey; in the meantime, and in col-
Te Patiki – Palmerston North Astronomical Society Inc September 2010 laboration with Telespazio, e-Geos and metallic meteorite fragments, includ- intense interest for geologists, astro- the Italian space agency ASI, the Kamil ing one 83-kg chunk thought to have physicists and even archaeologists. region was analyzed using satellite da- split from the main meteorite body ―We are still determining the geochro- ta and in particular high-resolution shortly before impact (it was found nology of the impact site, but the crater radar images provided by the ASI- 200 m away from the crater). The joint is certainly less than ten thousand operated COSMO-SkyMed satellite team also conducted a thorough geo- years old — and potentially less than a constellation. logical and topographical survey, using few thousand. The impact may even
ground-penetrating radar to create a have been observed by humans, and
Expedition to the Egyptian desert 3D digital terrain model. Geomagnetic archaeological investigations at nearby
The two-week, 40-person expedition and seismic surveys were also carried ancient settlements may help fix the included Egyptian and Italian scien- out. date,‖ says Dr Folco. The data gathered
during the expedition will be very use-
Ground truth ful to ESA’s SSA activities for risk as-
for small-scale sessment of small asteroids with orbits
impact craters that approach Earth, a category to
The researchers which the Kamil impactor originally
were stunned to belonged.
find that Kamil
crater, named af- Editor’s note (Anthony Watts):
ter a nearby rocky The intriguing story of the Kamil
outcrop, remains crater discovery will be presented in a tists, as well as numerous local support pristine, and must have been created joint paper by Telespazio, e-Geos, ASI workers, and was conducted as part of relatively recently. ―This demonstrates and INAF, ‘Radar observation of im- the 2009 Italian-Egyptian Year of Sci- that metallic meteorites having a mass pact craters using COSMOSkyMed’ at ence and Technology (EISY). It was on the order of 10 tonnes do not break the European Planetary Science Con- also supported with funding by ESA’s up in the atmosphere, and instead ex- gress (EPSC) 19-25 September 2010,
Space Situational Awareness (SSA) plode when they reach the ground and in Rome. A public and media outreach programme. After a tiring, GPS- produce a crater,‖ says ESA’s Dr Detlef event, ‘Kamil: a Lunar Crater on guided, three-day drive across the de- Koschny, Head of Near Earth Objects Earth’, will be presented on 23 Sep- sert in 40°C heat, the team reached the segment for the SSA programme. tember at the University of Rome . crater. They collected over 1000 kg of Kamil crater has become the target of
Te Patiki – Palmerston North Astronomical Society Inc September 2010
Weird water lurking have broken down into oxy- inside giant planets gen and hydrogen ions. The study also indicated that the convecting zone cannot ex- tend deeper than about half- What glows yellow and behaves way down to the planets' cen- like a liquid and a solid at the tres. If it were thicker, it same time? Water - at least in would produce a more orderly the strange form it appears to field like that of a bar mag- take deep within Uranus and net. Neptune. This exotic stuff might help explain why both planets have bizarre magnetic fields. The transition from convec- tion to non-convection at the depth calculated by Stanley Simulations in 1999 and an ex- and Bloxham might seem ir- periment in 2005 hinted that relevant, since the superionic water might behave like both a Superionic water may extend water takes over here. But superi- solid and a liquid at very high pres- from the core to halfway to the onic water also conducts electricity, sures and temperatures. Under via the flow of hydrogen ions. So such conditions, the oxygen and cloud surface. something must be stopping the hydrogen atoms in the water mole- superionic water from churning and cules would become ionised, with making the magnetic field more the oxygen ions forming a lattice- the atmospheric pressure on Earth. orderly. like crystal structure and the hy- The results show that a layer of drogen ions able to flow through superionic water should extend the lattice like a liquid. This from the rocky core of each planet One possibility is that superionic water is mostly transparent to in- "superionic" water, forming at tem- out to about halfway to the surface frared radiation, or heat. The elec- peratures above 2000 °C or so, (Icarus, DOI: 10.1016/ trons in superionic water can ab- should glow yellow. j.icarus.2010.08.008). sorb infrared radiation, but simula- tions indicate they tend to stay The extreme conditions that exist That tallies nicely with the results near the oxygen atoms, making deep within Uranus and Neptune of a 2006 study led by Sabine most of the space transparent to could be ideal for superionic water Stanley, now at the University of heat. That would make it easy for to form. But whether it really oc- Toronto, Canada, and Jeremy Blox- heat from the planets' cores to ra- curs inside these planets, and in ham of Harvard University, at- diate through the superionic water what quantities, has never been tempting to explain both planets' rather than building up at its base, clear because of uncertainty over curious magnetic fields. Whereas as would be needed for convection the exact pressures and tempera- Earth's magnetic field resembles to occur. tures needed to make it. that of a bar magnet, on Uranus and Neptune nearby patches of the Laurence Fried of the Lawrence Now the most detailed computer surface can have fields of opposite Livermore National Laboratory in models yet, created by a team led polarity. California is impressed by the new by Ronald Redmer of the University Stanley and Bloxham's work sug- work: "This is a new frontier that of Rostock in Germany, suggest gested that the interiors of both promises much insight into plane- both planets possess a thick layer planets contain a narrow layer of tary structure." of the stuff. The simulations as- electrically conducting material sume the most extreme conditions that is constantly churning, which possible inside both planets, with generates magnetic fields. This http://www.newscientist.com temperatures reaching up to 6000 conducting layer would be made of °C and pressures 7 million times ionic water, in which the molecules
Left: On per- haps the best day of the month from left, Mark Cul- len, Bob Kent, Ray Watchman and Myles Brunsdon had a very productive day getting the roof ready on Sluggish Creek Observatory. Te Patiki – Palmerston North Astronomical Society Inc September 2010
Awesome death spiral of a bizarre effective at absorbing star visible light), and can completely block the I sometimes think I’ve seen everything there is in the light from the star. All sky, with nothing new left to see. we see is the warm glow from the cocoon Then I get a rude — but welcome — wake-up call. as an infrared glow.
Check. This. Out. AFGL 3068 is a carbon star and most likely evolved just like this, but with a difference: it’s a binary. As the two stars swing around each other, the wind from the carbon star doesn’t expand in a sphere. Instead, we see a spiral pattern as the material ex- pands.
This is called the sprinkler-head ef- fect. As a sprinkler spins, the jet of water appears to take a spiral shape. Each individual drop is moving direct- ly away from the sprinkler head, but the rotation of the head itself creates a global spiral pattern, with the arms appearing to expand. It’s not precise- ly an illusion — the spiral pattern is definitely there — but the arms aren’t an actual physical structure. It’s just the way we interpret the way the drops move away from the sprinkler. We see the same thing (on a much smaller scale!) when spinning comets give off gas, too.
Going back to our sprinkler analogy, if you’re standing in the yard as the sprinkler spins, you get hit with a It’s real, and it’s the dying gasp of a very, very strange blast of water. Wait a few seconds and you get hit star system. again. Obviously, the time between soakings is the time it takes the sprinkler head to spin once, right? The name of this thing is AFGL 3068. It’s been known That means that we can measure the arms of AFGL as a bright infrared source for some time, but images 3068’s spiral and calculate the rotation period of the just showed it as a dot. This Hubble image using the binary! Advanced Camera for Surveys reveals an intricate, delicate and exceedingly faint spiral pattern. It’s so The expansion rate of the spiral material is about 15 faint no one has ever detected it before! km/sec (9 miles/sec). Given that distance, the time it takes between spirals turns out to be a little over 700 So what’s going on here? First off, this is not a spiral years. So if you were hovering in space outside this galaxy! It’s a binary star*, two stars that orbit each object and an arm swept past you, you’d have another other, located about 3000 light years away from us. 700 years before the next one blew your way again. One of the stars is what’s called a carbon star, similar to the Sun but much older. The Sun is still happily fus- But there’s more! Using the monster Keck 10-meter ing hydrogen into helium in its core, but older stars infrared telescope, the astronomers who observed the run out of available hydrogen. Eventually, they fuse object were able to see through the dark material to helium into carbon. When this happens the star swells the binary inside (IR gets through the thick cloud of up and becomes a red giant (note: that’s the brief ver- material more easily than visible light). Making some sion; the actual events are a tad more complicated). simple assumptions on the masses of the stars, they find the orbital period is about 800 years: very close to Red giants tend to blow a lot of their outer layers into the spiral pattern’s period, given their estimations. space in an expanding spherical wind; think of it as a super-solar wind. The star surrounds itself with a cloud That also lets me measure the number of spirals — of this material, essentially enclosing it in a cocoon. In roughly five — and calculate the size of this object: general the material isn’t all that thick, but in some of about a third of a light year across, or more than 3 these stars there is an overabundance of carbon in the trillion kilometres! outer layers which gets carried along in these winds. In these cases the material is very dense and opaque Coooool. (carbon forms long, complex molecules that are very
Te Patiki – Palmerston North Astronomical Society Inc September 2010
So after boggling at this picture for a few minutes and stars is very, very dim, so it’s amazing to think it may marvelling at the object it depicts, I had to wonder: be the only source of light on this object. Note that while carbon stars are rare, they’re not totally un- the spiral is slightly brighter on the right side than the known, so why don’t we see more of these amazing left. It turns out that the galactic plane — where stars spirals? are most populous — is in that direction, so that fits. I have to wonder about that bright star in the image, I think I know why. For one thing, the carbon star at too. It looks to be in the right direction as well, but we the centre would have to be in a binary. That cuts don’t know if it’s really close to us (in the foreground) back on their numbers. And more importantly, on a or much more distant (in the background). In other galactic timescale they just don’t last all that long; words, it may be way too far from AFGL 3068 to be millennia as opposed to millions or billions of years, so illuminating it. we have to catch one at just the right stage. I doubt there are more than a handful of these objects in the All in all, this is an amazing system. The beauty of it is entire Milky Way. undeniable, as well as the astonishing and intricate nature of how it was formed. And for me it holds even And also… this thing is faint. Really faint. This picture more charm… because it reminds me that there are was made using 33 minutes of time on one of Hubble’s always more things to see, more surprises the Uni- most sensitive cameras, and you can still barely see it. verse holds for us. Why is it so faint? Well, the stars inside can’t light it up; their light is blocked by the material closer to the stars. So what is lighting it up? http://blogs.discovermagazine.com/badastronomy/
Get this: the astronomers who observed AFGL 3068 think the spiral is being lit by galactic starlight. That’s incredible. The combined light of the distant
NASA to Send a Probe little toasty as one gets that the particles in a special Into the Sun close to the Sun. Solar Probe cup for direct analysis. Plus will utilize a special heat – Wide-field Imager: prin- NASA recently announced its shield made of an 8-foot (2.4 cipal investigator, Russell choices for the experiments to m), 4.5 inch (11 cm)-thick spe- Howard, Naval Research fly aboard the Solar Probe Plus cial carbon-composite foam Laboratory in Washington. spacecraft, which is slated to plate that will protect the craft This telescope will make 3 launch no later than 2018. This from temperatures of up to -D images of the sun's spacecraft will perform the un- 2600 degrees Fahrenheit (1400 corona, or atmosphere. precedented task of flying into degrees Celsius) and intense The experiment actually the Sun's atmosphere – or co- solar radiation. The heat shield will see the solar wind and rona – to take measurements is a modified version of that provide 3-D images of of the plasma, magnetic fields which was used in the MESSEN- clouds and shocks as they and dust that surround our GER mission to Mercury. approach and pass the nearest star. It will be the first spacecraft. This investiga- human-made satellite to ap- NASA has chosen five science tion complements instru- proach the Sun at such a close projects out of the thirteen that ments on the spacecraft proximity. were proposed since 2009. The providing direct measure- selected proposals are, accord- ments by imaging the The previous record-holder for ing to the press release: plasma the other instru- a spacecraft that approached ments sample. Solar Wind Electrons Al- the Sun was Helios 2, which – Fields Experiment: prin- phas and Protons Investi- came within 27 million miles cipal investigator, Stuart gation: principal investi- (43.5 million kilometres) of the Bale, University of Califor- gator, Justin C. Kasper, Sun in 1976. Solar Probe Plus nia Space Sciences Labor- Smithsonian Astrophysical will shatter that record, flying atory in Berkeley, Calif. Observatory in Cam- to 3.7 million miles (5.9 million This investigation will bridge, Mass. This investi- kilometres) of the Sun's surface make direct measure- gation will specifically at its closest approach. In flying ments of electric and count the most abundant so close to the Sun, the space- magnetic fields, radio particles in the solar wind craft will be able to get amaz- emissions, and shock — electrons, protons and ingly detailed data on the struc- waves that course helium ions — and meas- ture of the atmosphere that through the sun's atmos- ure their properties. The surrounds the Sun. pheric plasma. The exper- investigation also is de- iment also serves as a signed to catch some of As you can imagine, it gets a giant dust detector, regis-
Te Patiki – Palmerston North Astronomical Society Inc September 2010
tering voltage signatures ment of scientific perfor- This is the opposite of a gravity when specks of space mance and act as a com- assist, or "slingshot", in which a dust hit the spacecraft's munity advocate for the satellite gains energy by flying antenna. mission. by a planet. In the case of So- – Integrated Science In- lar Probe Plus, as well as that of Two important questions that vestigation of the MESSENGER, multiple flybys of the mission hopes to answer is Sun:principal investigator, the perplexing mystery of why Venus imparts some of the David McComas of the the Sun's atmosphere is hotter craft's energy to Venus, there- Southwest Research Insti- by slowing down the spacecraft. than its surface, and the mech- tute in San Antonio. This anism for the solar wind that investigation consists of emanates from the Sun into the The Solar Probe Plus mission is two instruments that will Solar System. The spacecraft part of NASA's "Living With a take an inventory of ele- will have a front-row seat to Star Program", of which the ments in the sun's atmos- watch the solar wind speed up Solar Dynamics Observatory is phere using a mass spec- from subsonic to supersonic also a mission. This program is trometer to weigh and speed. designed to study the impact sort ions in the vicinity of our Sun has on the space envi- the spacecraft. ronment of the Solar System, Because of the conservation of – Heliospheric Origins and acquire data to better momentum, it takes a lot of with Solar Probe Plus: slowing down to send a space- equip future space missions. principal investigator, craft towards the Sun. The Marco Velli of NASA's Jet Earth and objects on the Earth Source: NASA press release, Propulsion Laboratory in are traveling around the Sun at APL mission site (http:// Pasadena, Calif. Velli is an average of 30 kilometres per solarprobe.jhuapl.edu/ the mission's observatory second (67,000 miles per index.php) scientist, responsible for hour). So, to slow the space- serving as a senior scien- craft down enough to get it tist on the science work- http://www.universetoday.com close to the Sun, it will have to ing group. He will provide fly around Venus seven times! an independent assess-
Ancient Greeks spotted Halley's time of year characterised in this region by strong comet winds, it was in the western sky. At around this time, the Earth was moving under the comet's tail, so its debris field would have made shooting stars. A CELESTIAL event in the 5th century BC could be the earliest documented sighting of Halley's comet - and it marked a turning point in the history of astronomy. None of this proves the comet's identity, but Graham says such major comet sightings are rare, so Halley must be a "strong contender". Previously, the earliest According to ancient authors, from Aristotle onwards, known sighting of Halley was made by Chinese astron- a meteorite the size of a "wagonload" crashed into omers in 240 BC. If Graham and Hintz are correct, the northern Greece sometime between 466 and 468 BC. Greeks saw it three orbits and more than two centu- The impact shocked the local population and the rock ries earlier. became a tourist attraction for 500 years.
The researchers' analysis reveals this moment to be a The accounts describe a comet in the sky when the crucial turning point in the history of astronomy. Plu- meteorite fell. This has received little attention, but tarch wrote in the 1st century AD that a young astron- the timing corresponds to an expected pass of Halley's omer called Anaxagoras predicted the meteorite's fall comet, which is visible from Earth every 75 years or to Earth, which has puzzled historians because such so. events are essentially random occurrences.
Philosopher Daniel Graham and astronomer Eric Hintz After studying what was said about Anaxagoras, Gra- of Brigham Young University in Provo, Utah, modelled ham concludes that he should be recognised as "the the path that Halley's comet would have taken, and star of early Greek astronomy". Rather than predicting compared this with ancient descriptions of the comet a particular meteorite, he reckons Anaxagoras made a (Journal of Cosmology, vol 9, p 3030). For example, general statement that rocks might fall from the sky. the comet was said to be visible for 75 days, accompa- nied by winds and shooting stars, and in the western sky when the meteorite fell. At this time, says Graham, everyone thought that ce- lestial bodies such as the moon and planets were fiery, lighter-than-air objects. But after observing a solar The researchers show that Halley's comet would have eclipse in 478 BC, Anaxagoras concluded that they been visible for a maximum of 82 days between 4 were heavy, rocky lumps, held aloft by a centrifugal June and 25 August 466 BC. From 18 July onwards, a force. This implied that solar eclipses occurred when
Te Patiki – Palmerston North Astronomical Society Inc September 2010 the moon blocked the light from the sun. It also Did Halley's comet play a role? It is always possible meant that if knocked from position, such a rock that the comet might have nudged a near-Earth aster- might crash to Earth. oid from its course and sent it hurtling towards north- ern Greece. From that point on, the idea of rocks in "When the meteorite fell, no one could deny it," says Graham. "The headline was 'Anaxagoras was right'." the sky was accepted, and the Greeks had a new un- derstanding of the cosmos.
Mars moon may have Phobos turns out to have a density formed like our own of only 1860 kilograms per cubic metre, which is barely half that of the silicate minerals present. The The Martian moon Phobos may simplest explanation is that the have been blasted off its mother moon is riddled with holes, which planet by a violent impact, or built fits the reassembly idea. Larger from fragments of a much larger rocks would gather together first, moon that was destroyed long ago, followed by layers of increasingly according to observations from fine material. Europe's Mars Express spacecraft.
But Pascal Lee of the Mars Institute If confirmed, the result would in Moffett Field, California, says it overturn the prevailing theory that may be too soon to rule out a cap- Phobos was once a wandering as- tian crust that were thrown into ture scenario, since some of the orbit after a large object struck teroid that got captured by silicate minerals observed by Mars Mars – a similar process probably Mars. That theory was based on Express are also seen on carbon- created Earth's moon. the fact that visible light reflected rich asteroids. "The data seem ex- off the moon closely matches the citing, but from what I have seen, spectrum of a common type of car- Alternatively, Mars may once have they may still be consistent with bon-rich asteroid. "For the last 30 had a much larger moon that Phobos being a captured asteroid," years, the scientific community has formed locally out of the same in- he told New Scientist. supported this scenario," says gredients, and therefore had a sim- ilar composition to the Red Planet. Marco Giuranna of the National He adds that a captured asteroid If the large moon moved too close Institute of Astrophysics in Rome, could also explain Phobos's low to Mars, gravitational forces would Italy. density, if it was broken apart by a have torn it apart, leaving behind a large impact and later reassembled little debris that then came togeth- Now, data from the Planetary Fou- from the resulting debris. er to form Phobos. rier Spectrometer on Mars Express reveals that the spectrum of far Russia's upcoming Phobos-Grunt infrared radiation from Phobos in- These debris-coalescence scenarios stead resembles that of silicate fit new observations from the Ra- mission could help pin down Pho- minerals found on the Red Planet. dio Science Experiment on Mars bos's origin more firmly when it "The composition is closely related Express, which has been used to returns samples of the moon to measure the motion of the space- to Mars," says Giuranna, who Earth. helped analyse the data. craft as it passes Phobos. Small changes in trajectory reveal the strength of Phobos's gravity, which That suggests Phobos may have can be used to work out the http://www.newscientist.com coalesced from chunks of the Mar- moon's density.
Te Patiki – Palmerston North Astronomical Society Inc September 2010
The Beauty of a barred Spiral Any sort of perturbation — the passing of a nearby galaxy, for example, or possibly even a wave of super- Galaxies come in a lot of flavours. And even in the ma- nova explosions — can disturb the disk, causing the jor categories (spiral, elliptical) there are sub- spirals to form. flavours… like barred spirals, which are truly cool and
The same goes for bars. That’s the long, horizontal, relatively straight feature going across the galactic centre. That’s a natural consequence of gravity in some galaxies, and in fact we are now pretty sure the Milky Way is a barred spiral, though our bar isn’t as prominent as the one in NGC 1365.
In the side-by-side image here (click it to get a much bigger picture), visible light from the galaxy is on the left and the IR image on the right. The dust is better at blocking visible light, so you can really see where the dust is… and once again, the bar is littered with it. Again, that makes sense since we’re seeing lots of star weird and awesome. Behold! formation there. That’s NGC 1365, a barred spiral about 60 million light years away in the Fornax cluster, as seen by the Interestingly, the central bulge in NGC 1365 is elon- HAWK-1 camera on the Very Large Telescope in Chile. gated, and at an angle with respect to the bar. That HAWK-1 is sensitive to infrared light, from just outside bulge has mostly older, redder stars — that’s why it’s our human eye’s range to wavelengths about four so prominent in the IR image. Those kinds of stars times longer than we can see. Those wavelengths are pour out infrared light. But it’s also lacking in dust and pretty good (though not perfect) at penetrating dust gas (the image is very smooth, indicating it’s the com- clouds in galaxies, which block visible light. So mostly bined light of billions of stars; gas and dust would what you see in images like this one is light from stars, make it patchy like the bar and arms). That’s another along with gas clouds. Where you see dark lanes is indicator it’s old; all the gas has long ago been used up where the dust is so thick it blocks even the infrared making stars. light, too. It’s amazing what you can learn about a galaxy simply The two major spiral arms are obvious enough, as well by comparing two images taken at different wave- as some smaller ones (called spurs) too. These are not lengths. But that’s something astronomers have known physical spirals; stars near the centre of the galaxy for almost a century now; what we see with our eyes revolve faster around the centre than ones farther out, is not even close to the whole story, and it’s only by and so if the arms were "real" they’d quickly (well, going outside our natural limitations that we can truly over a few hundred million years) wind up into a tight understand the Universe. little curl. But we see spiral arms in galaxies of all ag- es, so we know they’re not transient, and must be sta- If there’s a morality lesson in that, I leave it to you to ble features. figure it out.
In the past few years the thinking is that the arms are traffic jams, literally regions where stars, gas, and dust http://blogs.discovermagazine.com/badastronomy/ pile up as they orbit the galaxy. Supporting this idea is that the arms are regions of intense star formation, which you’d expect if gas clouds are rear-ending each Opposite Page Bottom: Paul Tervit of Marton has other in these jams. The clouds collapse after colliding and form stars. That also makes a lot of dust, and imaged these views of the outer gas giants Uranus again you see a lot of that in the arms. and Neptune as well as some of their major satel- lites. Well done Paul and we look forward to seeing What causes the spiral pattern? That’s complicated and has to do with the way gravity works in a disk of star. more of your work in the future.
Te Patiki – Palmerston North Astronomical Society Inc September 2010
The star photographers who cap- tured the night sky The Northern Lights are a beguilingly beautiful natural light show, the result of interactions between solar The competition to be Astronomy Photographer of the winds and the Earth's magnetic field. However, the Year 2010 was fierce. We reveal the shots that the exact cause of the mesmerising glows remains some- Royal Observatory in Greenwich, London, deemed thing of a mystery. most stellar: capturing eclipses, the Northern Lights, the dim and distant Veil nebula, and more. This picture, taken by Fredrik Broms, shows the Northern Lights seen looking up through the trees of All winning images are on show at the Royal Observa- the boreal forest on the island of Kvaløya, Norway. It tory from today. The exhibition is free of charge and was highly commended in the Earth and Space cate- runs until February. gory.
Blazing Bristlecone
Orion Deep Wide Field
Orion is probably one of the best-known constellations in our night sky – but this picture, taken by Rogelio Bernal Andreo, shows it as few will have seen it be- fore. As a result, it was crowned winner of the Deep Space category. The panorama shows Orion's belt In the White mountains of California, an ancient bris- clearly – it's the three bright stars on the left of the tlecone pine stands before the Milky Way as a meteor picture. But you can also see the Horse head nebula streaks through the night sky. The pine is the middle and the Orion nebula. tree in the picture. The red glow on the tree in the foreground is seren- These clouds of gas, dust and other materials are dipitous, created unintentionally as the photographer, slowly cooling and condensing – and may eventually Tom Lowe, set up his equipment. It's an accident that form new stars and planets. paid off: this picture won the Earth and Space catego- ry, and was announced overall winner, too. The Veil Nebula
Surrounded by Space
Te Patiki – Palmerston North Astronomical Society Inc September 2010
This photograph by Martin Pugh shows the Veil nebula, The Green Visitor in the constellation Cygnus, which is the faint remnant of a supernova that exploded over 5000 years ago.
When the supernova exploded, the mass of expanding gases would probably have appeared as bright in the sky as a crescent moon – easily visible with the naked eye.
Now it's notoriously difficult to capture an image of the Veil, so enjoy it while you can. The judges certainly did – this photograph was declared runner-up in the Deep Space category.
Siberian Totality
Comet Lulin, named after the observatory in Taiwan where it was discovered, came within 38 million miles of Earth last year. Richard Higby took this picture of the comet as it passed by on what was probably its first trip into our solar system – and the judges highly commended the result in the Our Solar System cate- gory. Its green tinge comes from the gases that make up its surrounding "atmosphere" – which is thought to be around the same size as Jupiter.
A Perfect Circle
Watching a total eclipse of the sun is a majestic, stir- ring experience – and a rare one at that.
But when the moon passes between the Earth and the sun, we're not plunged into complete darkness. This picture, taken by Anthony Ayiomamitis, shows the ac- tivity stretching out beyond the surface of the sun – known as the corona – in all its glory. It was declared winner of the Our Solar System category. This haze around the sun is actually made up of jets called spic- ules, which are about 500 kilometres across and up to several thousand kilometres high.
This solar eclipse was photographed in India last year. The photographer, Dhruv Arvind Paranjpye, caught it
through clouds, cleverly using them as a filter. What makes this photograph even more impressive is that Dhruv is just 14 years old, which compelled the judges to make him Young Astronomy Photographer of the
Year.
http://www.newscientist.com
Te Patiki – Palmerston North Astronomical Society Inc September 2010
Earthquake Damages on the 'scope last night, it had Some Canterbury Ob- barely moved even though it's only Interestingly, a fork-mounted servatories on a tripod.‖ Celestron C11 left standing on its drive base in a storeroom had been As most readers will know, on Sep------toppled by the 'quake. It must tember 4 New Zealand had its big- The Canterbury Astronomical Soci- have taken amazing force to do gest earthquake near a metropoli- ety's observatory is at West Mel- this. The C11 will replace the tan area since 1931. It had a Rich- ton, midway between Darfield and Cooke. ter magnitude of 7.1 and was cen- Christchurch. Phil Barker reported: tred near Darfield, around 40 km Overall, however, everything sur- west of Christchurch. It occurred ―I went to the West Melton Obser- vived. As a serving Police officer I on a previously unknown fault bur- vatory to see if all was well the day have been involved in the Police ied under 16000 year-old ice-age of the quake. The roll-off roof of operation surrounding this event. gravels. Thanks to the shake being the 16-inch Meade building was in The way this 'quake seemed to at 4:35 on a Saturday morning an unnatural position. When I wreak devastation in some areas there was no loss of life, despite opened the door I found the cover and virtually leave others alone has major damage to old buildings in of the telescope had been thrown amazed me. The ground under- Christchurch. off and the tube was in unusual neath appears to be a significant position. contributor to this. Around Avon- Townsend Observatory, situated in side, Kingsford Street and Bexley I a stone tower in the Arts Centre -- The roof had run off and back on understand in the order of 2000 the old Canterbury University and had been held in place with 2 houses will need rebuilding. Sever- buildings -- in Christchurch's CBD bolts that look to have barely held al houses have split cleanly in two; has been badly damaged. Press on. When we went to use the 16- some quite recently built.‖ reports say that the tower is inch RCX last Wednesday it was cracked. Nothing has been said out of collimation -- it has never ------about the state of the telescope, needed adjustment since it was put Stu Parker in Oxford, about 30 km presumably because the tower in the shed -- and the polar align- north of the epicentre said: is unsafe to enter. ment is well out now. It took quite ―Yes, it was quite a jolt alright. My a while getting it well aligned, Observatory had minor damage to mostly by Ashley Marles. It is now the pier and a crack in the con- Brian and Pauline Loader who live back to square one. It doesn't ap- crete. The polar alignment was out at Darfield reported: pear damaged, thankfully. and I did another T-Point. The in- teresting thing was that I was re- ―It is really remarkable how little The Cooke 5-inch pier was shaken motely supernova hunting that effect the 'quake had. The shaking loose from the grounding bolts morning, so the 'scope took a 30 was fairly alarming, noisy and around its Base and was about a sec image during the earthquake. seemed to go on for a long time, foot from its original position. No The images before and after were but probably no more than a mi- damage and the telescope is fine. fine, but the one at 4:35 a.m. nute in reality. But seemingly no (The Cooke has been recalled by rocked and rolled all over the damage to our house and only two Carter Observatory to be no longer place. I sent the image to a few or three ornaments/flower pots used for astronomical viewing, sad- people and it proved quite popular; broken. Even the books stayed on ly. At least it survived). I was able more so than most, if not all, of my the book shelves. to move it back with some effort as other images!!! the pier weighs in the order of 110
kilograms. As far as we can see, very little Stu's earthquake image will be on damage in our little town. Two or http://parkdale-supernova- No sign of damage in the 5 metre three chimneys toppled, mostly on factory.webs.com/ older houses, and of course stock dome that houses the 14.5-inch in shops scattered on the floor. We classical Cassegrain. In the lodge had power back on just over 12 things were strewn all over the hours after the main shake. place. In the library a bookcase was knocked over and its contents I did a quick polar alignment check scattered.
What’s The Use of Astronomy? ies have underpinned the formulation of our current understanding of physics: the fundamental forces, in particular gravity as described by Einstein´s Humans have always gazed up at the Heavens and wondered what General Theory of Relativity; and the building-blocks of matter and was beyond their everyday world. the theory describing them, quantum theory. Today, the universe continues to provide a laboratory for testing basic theories that lead Astronomy is the oldest science. The earliest civilizations made to a deeper understanding of nature and our own place in it. astronomical observations that led to the units of time we use to- day—possibly the first scientific measurements made. Many human Astronomy now covers a huge range of topics: understanding how activities, particularly navigation, have depended on observations of the universe got started and how its large scale structure evolved the Sun, Moon and stars. into what we see today; the formation and evolution of galaxies, stars and planetary systems; and, excitingly, the search for planets Over the past couple of centuries, more detailed astronomical stud- that might support life. A major mystery recently uncovered is the
Te Patiki – Palmerston North Astronomical Society Inc September 2010
existence of "dark energy" which is accelerating cosmic expansion. ology—exploring the conditions in which life could exist elsewhere The dynamics of the universe seem to be dominated by this phe- in the universe - could explain how life first evolved on Earth. nomenon, as well as by large amounts of invisible "dark matter". The universe we see directly is only a small component of what is really out there.
Discoveries made via astronomical observations also play a pivotal role in shaping progress in other fields. A major goal of nuclear physics is to understand how the elements are made in stars. Study- ing the outer layers of the Sun and other stars tells us about the physics of plasmas relevant to clean nuclear-energy generation. Ex- ploring the geology and atmospheres of planetary bodies in the solar system may throw light on climate change on our own planet, while the burgeoning science of astrobi-
Most Massive Star icist at Sheffield University, used the Very Lightweight stars, such as our sun, live a Found (So Far) Large Telescope (VLT) in the Atacama de- long and quiet life. Massive sert of northern Chile and archival material stars, on the other hand, are very rare, and from the Hubble space telescope to study have a short but intense The most massive star yet found is 265 the young clusters NGC 3603 and RMC existence before exploding as supernovae. times the mass of the sun and 136a. NGC 3603 is about 22,000 light-years millions of times brighter. The discovery has away. For more see http://www.guardian.co.uk/ astonished scientists, who thought it was science/2010/jul/21/monster-bright-star- impossible for stars to exceed more than These enormous stars churn out vast quan- r136a1- 150 times the mass of the sun. When the tities of material, and, close up, would look as star was born it could have been more than fuzzy compared with the sun. They are ex- twice as massive. tremely rare, forming only within the dens- est star clusters. Distinguishing the individu- The star is in the cluster RMC136a. The al stars was made possible by the use of cluster appears as a star-like point (in most infra-red instruments on the telescope. telescopes) at the centre of the Tarantula nebula, 165,000 light-years away in the "Owing to the rarity of these monsters I Large Cloud of Magellan. RMC 136a is a think it is unlikely that this clutch of monster stars, including several new record will be broken any time soon," that are tens of times larger than the said Crowther. R136a1 has now overtaken sun and several million times brighter. Some the likes of Eta Carinae and the Pistol Star have surface temperatures of more than as the most massive and luminous known 40,000C • seven times hotter than our own star in existence. Like these other giants it sun. has a large radius for its mass and surface temperature. A team led by Paul Crowther, an astrophys-
Right: Laying out the rafters and beams in readiness to put the roof frame together. With the numer- ous westerly gales that we have had this month the addition of side supports on the east & west sides by Myles proved to be inspirational. Well spotted that chap!
Te Patiki – Palmerston North Astronomical Society Inc September 2010
Did you know…? If undelivered,
We now of 490 extrasolar planets, most of them discov- please return to ered by the radial velocity they impart on their star as they orbit. Ian Cooper RD3 Palmerston North
Less than 12 hours before the magnitude 7.1 crepuscular rays are very rarely seen from thing while Rhiannon McNish had a very nerv- Darfield earthquake that rocked Canterbury here and this display was the best that I have ous flight from Palmerston North to Christ- on September 4th, 2010, I photographed this ever seen. church 12 hours after the event. Rhiannon has fine display of the very rare sky phenomenon, reported that has felt only two of the after- As for the earthquake young Himatangi Beach anti-crepuscular rays. Often seen from the east shocks to date, but that they are now back in astronomer Brenden Johnstone was in Christ- coast of both islands for some reason, anti- their Halls of Residence. church at the time and experienced the whole