The Planets in January 2014

Mercury, the closest planet to the Sun, has returned to the evening sky this month for a brief sojourn. Unfortunately you will need a good clear western horizon to see it. By the 19th it should be about 5 degrees above the south-western horizon and only visible for about 30 minutes after the Sun has set. By the end of January it will be visible for closer to 1 hour after Sunset and by mid February it will no longer visible in the evening sky as it heads off to its inferior conjunction appointment with the Sun. It will return later February as the ‘morning star’ and remain in the morning skies until mid April. An inferior conjunction occurs when the Earth and interior planet are on the same side of the Sun.

Venus started the month as the ‘evening star’ after shining so brightly in the western sky on January 11th it Venus passed between the Earth and the Sun and so had its inferior conjunction with the Sun. It will be come visible as the ‘morning star’ before dawn around January 19/20. A nice photo opportunity for all the morning risers will occur on January 29th when a thin crescent Moon will be above Venus to the south-east in the morning twilight.

Earth: trivia note for the month – on January 4, the Earth was at its closest to the Sun for the year. The Sun was only 147,089,638 km away.

Mars is slowly returning to our evening skies in January. Spending the month in the constellation of Virgo it will rise around 12:30am local summer time and rising earlier each night by around 2 minutes, finishing the month by poking its head up around 11:30pm local summer time. Currently the best time to check it out is still in the early morning sky about an hour before morning twilight. On the 23 and 24th of the month the Moon will be very close to Mars at around 12:30am.

Jupiter is visible most of the night at present. It will spend the month in Gemini. It is clearly the brightest object in the sky rising around 8:30pm. By January 22nd it will be setting at around 4:30am.  Having reached its yearly opposition – when it’s opposite the sun – rising in the east as the sun is setting in the west on January 5th. Even if you have only a small telescope, or a decent pair of binoculars, which you mount to keep steady the four main moons of Jupiter, Io, Europa, Ganymede and Callisto should be visible. These are the moons that were discovered by Galileo. Although all four may not be visible at the same time as they may be hidden as they pass behind the planets. It is always interesting to watch and note their positions over a few hours – just as Galileo did over 400 years ago.

Saturn rises well before the Sun in the constellation of Libra. By mid January it is rising at around 2am and in the early hours of Australia Day, just before sunrise around 5:30am Venus will be visible very low on the Eastern horizon the Moon and Saturn will be very close and higher in the same line in the sky will be Mars. Between Venus and Saturn is a red star known as Antares – the heart of the Scorpion. Antares also means ‘Mars-Like” so don’t let it trick you! Mars is higher than yellow Saturn in the sky and Antares, a star, is much lower. The rings of Saturn currently are open wide when viewed from the Earth, making them a fine sight in a small telescope.

If you have any questions about what you see in the sky or want more information please feel free to contact me – Donna Burton, University of Southern Queensland – Astronomy for Schools Co-ordinator North West NSW 63 John Street, Coonabarabran 2357, phone 6842 4343 or via email donna.burton@usq.edu.au and you can check out my blog at http://www.astronewsroom.com.

 

Photo Credits and Caption

 

Aust_Day_Planets.jpg – Australia Day Morning Planet Parade.

Created in the free planetarium software package – Stellarium. This chart shows you the sky looking East on Australia Day (Jan 26), 2014 at 5:15am AEDST. You will need a good south-eastern horizon but you can see Venus low in the East, the Moon and Saturn and orange-red Mars higher in the sky and to the North.

 

Get Ready for the Geminid Meteor Shower overnight this Friday/Saturday

As usual at this time of the year, the Earth is entering a stream of debris from rock comet 3200 Phaethon, which is the source of the annual Geminid meteor shower. Forecasters expect the shower to peak on Dec. 13-14 with as many as 120 meteors per hour.

This year the nearly full Moon will reduce the number of meteors you may see but it is still well worth a look. Expected to peak from about midnight Friday Australian Eastern Daylight Time (or 1300 UT) until 9pm (1000 UT) Saturday, this meteor shower will be visible in both hemispheres.

Though you do need to keep in mind that meteor showers often peak hours before or after predictions and for sure we certainly don’t know everything that a given meteor stream might have in store!

This shower is an interesting one though, with an equally interesting history and source. The Geminids were first identified as a distinct meteor shower by R.P. Greg of Manchester UK in 1862, and the estimated ZHR rose from about 20 to 80 through the 20th century. The parent source of this shower remained unknown until 1983, when astronomer Fred Whipple linked them to the strange “rock-comet” body 3200 Phaethon. This is an Apollo asteroid also thought to be a member of the Pallas family of asteroids, 3200 Phaethon seems to be shedding enough material to produce the annual Geminid meteor shower. This makes the annual shower rare as one not produced by a comet. It’s worth noting that 3200 Phaethon also passes extremely close – 0.14 AU – from the Sun at perihelion, and gets periodically “baked” during each 1.4 year passage.

In the 21st century, rates for the Geminids have stayed above a Zenith hourly rate (ZHR) of 120, now the highest of any annual shower. It’s worth noting that an extrapolated ZHR of almost 200 were seen in 2011 when the Moon was at an equally unfavorable waning gibbous phase! The Geminids always produce lots of fireballs, capable of being seen even under moonlit skies.

With our warmer nights down under it is a great time to get out and have a look! Jupiter is also looking good after about 10:30pm and Mars and Saturn are visible in the early dawn skies as well.

Comet ISON

There has been a lot of interest in the Comet 2012/S1 (ISON), more commonly known as Comet ISON. This comet has been predicted to become the comet of the century; this of course, may not eventuate. For those of us fortunate to have witnessed C/2006 P1 (McNaught) in January 2007 it will sure take a lot of beating.

The comet was discovered on 24 September, 2012, by two amateur astronomers in Belarus and Russia, using a 40-cm (16-inch) telescope. As it took them a day to confirm that the object was a comet, the organisation International Scientific Optical Network with which they are associated was credited with the discovery.

Over the past decade, hundreds of sungrazing comets have been discovered, but they are usually small, short-lived, and only seen by spacecraft designed to observe the Sun. Most sungrazing comets do not survive their trip around the Sun as they are disrupted by its intense radiation and gravity. Most of these, however, are quite small being only tens of metres across. The nucleus of Comet Ison is believed to be around 4km in diameter and hopefully its larger size will insulate the interior from the Sun’s energy.

One reason this is considered to be such an interesting comet is that it is believed to be making its first approach to the inner solar system. Along with this belief, comes the reason for all the uncertainty in the predictions as scientists can only guess at how bright it will become at the time it is closest to the Sun. There will be professional and amateur astronomers eagerly observing the comet from the ground and via the internet as a whole fleet of spacecraft have turned their cameras in its direction.

The comet has been gradually brightening as it speeds up on its journey towards the Sun. Unfortunately for us in the Southern Hemisphere just before and just after it passes behind the Sun on November 29, it will be below the horizon in both the morning and evening sky. This is the time that the comet is most likely to be at it brightest. For northern hemisphere observers, at these times, it may even be naked eye or perhaps visible in binoculars. A few weeks later the comet’s outward trajectory, providing it survives its passage around the Sun, will bring it to just 0.4 times the distance from the Earth to the Sun.

But perhaps, the greatest unknown is, in fact whether or not the comet will actually survive its passage through the corona which is the Sun’s atmosphere. At the time it passes the Sun it will only 1.1 million kms away and the nucleus of the comet will be subject to a combination of both extreme heating approximately 5000 degrees Celsius, which is hot enough to melt iron as well as constant radiation bombardment.  Add to that the fact that the Sun’s strong gravitational pull will be trying to tear it apart. Still the best guess from scientists is that the nucleus or at least a large chunk of it will manage to sweep around the Sun and start making its way out of the solar system.

Comets are believed to be the frozen left-overs from the formation of our Solar System, originating in the Oort cloud. While comets have been in a deep freeze for the past 4 billion years, planets and asteroids have changed a lot from their original compositions. Better understanding of their ices, dust, and organic matter, and how they have changed over the past billions of years, tell us about the origins of our Sun, the planets, and, possibly, life on Earth. To astronomers, every bright comet is an opportunity to learn more about our Solar System.

 NOTE that it is always dangerous to look directly at the Sun. Do not use telescopes or binoculars to search for the comet, just your unaided eyes and block the Sun with a post or other convenient object. Take extreme care!

 

NACAA (Easter 2014) Bulletin 1

The First Announcement and Call for Submissions for NACAA 2014, Friday April 18 to Monday April 21, may be viewed or downloaded here. Check the bulletin for deadlines (earliest is October 2013), venue, and contact information.

The 26th NACAA will be held over Easter 2014, Friday April 18 to Monday April 21, hosted by the Astronomical Society of Victoria. The NACAA XXVI committees invites everyone interested in the “cutting-edge” of amateur astronomy to attend.

We are working to ensure that the programme will include an exciting mix of invited speakers, technical sessions, group discussions, hands-on workshops, and social functions. The 2014 Berenice Page medal is expected to be presented at the convention dinner. The Sunday night BBQ will be held at the Melbourne Observatory complex in the Botanical Gardens.

The venue for NACAA XXVI is the Rydges Bell City, 215 Bell Street, Preston. Situated in northern Melbourne, Preston is about fifteen minutes by car from Melbourne Airport. It is easily accessed by road via the Hume Freeway, Metropolitan Ring Road and other motorways, and by regular rail services to Bell. As well, the #86 tram travels from central Melbourne (Bourke Street) to the corner of Bell Street and Plenty Road in around 35 minutes.

Registrations for NACAA XXVI will commence in late 2013. A number of registration packages will be available, ranging from attendance at just one or two sessions or workshops, through to a full convention, dinner and BBQ package.

PROGRAMME

The core of the convention is of course its presentations, and we are asking you to consider making a contribution, by yourself or in a group. There are no restrictions on topics or themes, so long as the contribution is significant and interesting. Here are a few suggestions:

An address or poster

  • on an observational (or desk-bound) research programme you are involved in;
  • on a significant development in instrumentation and tools: optical, imaging, computational, electronic, whatever …
  • on your progress with a significant project or programme, national or worldwide;
  • to share your imaging successes with an appreciative audience;
  • an entertaining address aimed at promoting the enjoyment of astronomy;
  • on a significant club or local activity;
  • on an interesting piece of astronomical history.

A workshop or round-table meeting

  • on an observing or research technique you use;
  • helping amateurs move to a more advanced plane of astronomical activity;
  • with likeminded specialists to discuss or plan your field;
  • on an educational or outreach activity;

You can submit a proposal for consideration by the PC by completing the form on the NACAA website http://www.nacaa.org.au/2014/submission. The full submissions guidelines can be obtained from http://www.nacaa.org.au/2014/cfp.
Submissions should be made before

  • 2013 October 1 for workshops, colloquia, or symposia,
  • 2013 November 1 for oral presentations or round-tables,
  • 2014 March 1 for posters.

you have any questions about contributing to NACAA XXVI, you can contact the programme committee by email at programme2014@nacaa.org.au or via the NACAA web site.

 

 

 

 

25th Anniversary of SN1987a

This February marks the 25th anniversary of the discovery of Supernova 1987A.  A star, in the Tarantula Nebula within the Large Magellanic Cloud (LMC), called Sanduleak 69 202, exploded and became a supernova back on 24th February 1987.

It is now 25 years since the light from this cosmic explosion first reached us here on Earth. The star itself actually exploded about 168,000 years before, of course, with the light taking that long to reach us.

SN1987A has become the most studied star remnant in history and has provided great insights into supernovae and their remnants. It has some interesting connections to the Anglo-Australian Observatory and Siding Spring and is still being studied to this day.

SN 1987A was discovered by Ian Shelton and Oscar Duhalde at the Las Campanas Observatory in Chile on February 24, 1987, and within the same 24 hours independently by Albert Jones in New Zealand. On March 4–12, 1987 it was observed from space by Astron, the largest ultraviolet space telescope of that time. Hubble had yet to be launched.

On February 23rd, approximately three hours before the visible light from SN1987A reached the Earth, a burst of neutrinos was observed at separate neutrino observatories around the globe. This is likely due to neutrino emission (which occurs simultaneously with core collapse) preceding the emission of visible light (which occurs only after the shock wave reaches the stellar surface).

At 7:35 a.m. Universal time, Kamiokande II detected 11 antineutrinos, IMB 8 antineutrinos and Baksan 5 antineutrinos, in a burst lasting less than 13 seconds. Even though, the actual neutrino count was only 24, this was a significant rise from the previously-observed background level. This was the first time neutrinos emitted from a supernova had been observed directly, and marked the beginning of what is now ‘neutrino astronomy’.

The Supernova exploded in the Tarantula Nebula area near the edge of the Large Magellan Cloud – a satellite galaxy to our own. Even though its location in the LMC meant it was 10 times more distant than if it had been in our own Milky Way, it also meant that we had a relatively unobscured view of the supernova and its environment; there was never any ambiguity about its distance; and the fact that it lies so far south meant that observations could be done each night throughout the first year as it was always visible at some time during the night.

SN1987A was the brightest and closest supernova that has been seen since the invention of the telescope back in 1604. That supernova was called “Kepler’s Star” and the supernova was in our own galaxy around 20,000 light years away. It was so bright that it outshone Venus and Jupiter and was even visible in daylight for 3 weeks back then. The only other one in our own galaxy was “Tycho’s Star” seen in 1572 and also visible to the naked eye. There have only been a total of 8 naked eye supernova that are known.

SN1987 was also It was able to be seen quite easily with the naked eye, despite not even being in our own Milky Way galaxy. Visible for some months afterwards, it was easy to find and exciting to point out to others this bright new star in the LMC. 

SN1987A provided some significant opportunities  specific to the decade that followed and which came about as a direct result of the supernova discovery. These include the development of infrared instrumentation and spectropolarimetry which were evolving rapidly at the AAT and elsewhere. At the time of the supernova, photographic film was still in use at observatories and the internet did not yet exist. All discovery communications were done by telex between the various observatories around the world.

Data was shipped on large tapes back across to England and the other observatories to be reduced and analysed.

Even the introduction of CCDs, with their great sensitivity and dynamic range, made a major difference during the first few years. But much more importantly, the Hubble Space Telescope became available not long after the explosion.  We would have learned a lot less about SN1987A had it occurred a decade earlier, and there is unfortunately no guarantee that we will have any HST-like capability even 10 years from now.

Pioneer Astrophotographer,  David Malin, was working at the Anglo-Australian Telescope at the time of SN 1987A’s first sighting and was able to take several images of the light echoes of the supernova. One of his images is shown below.

Although the AAT observing schedule had been fully assigned for the semester through to June , when SN1987A erupted, data was able to be obtained on almost two thirds of the nights, and those observations took up 16% of the total time available. This was achieved by using up all the engineering, service and director’s time, as well as, requiring each observer to give up one hour per night of their time to allow observations with whatever instrument was on the telescope. The observers willingly co-operated and so much incredible data was able to be collected.

The emphasis was on observations that could best utilise the 3.9m aperture of the AAT or observations which best used the available instrumentation unique to that telescope: for example, speckle interferometry and spectro-polarimetry.

The Anglo-Australian Telescope was ideally situated as it was the only telescope from which the supernova was accessible and which had the necessary instrumentation to make the observations. Even though there were some changes necessary to the existing IPCs based spectro-polarimeter which was optimised for observing much fainter object.

 Data was collected by the non-optimised instrument 4 days after the discovery and it was found that the instrument issues meant that data accuracy would be impacted. So over the next 10 days the engineers worked to modify the instrument to use CCDs as detectors and the first observations with were made on March 7th, a mere 2 weeks after the supernova was first seen.

One particular highlight was the very rapid construction, by Peter Gillingham, of a temporary Littrow spectrograph, which had a resolving power of almost one million, which  was able to be used to study interstellar lines. It was available within 2 months of the Supernova. It has been called the  “wooden spectrograph”.

The new CCD spectropolarimeter – was built up from the RGO spectrograph  plus Pockels cell plus IPCS which itself was a well proven set-up. In order to make it all work with incredibly bright object – the instrument was modified to use the CCD detectors. This raised further hurdles which were one by one overcome and they were able to collect over the next 12 months the first ever spectropolarimetry data on a supernova.

A common-user version of this very successful Ultra-High Resolution  Spectrograph  (UHRF) was later  commissioned and operates on the telescope to this day. Peter Gillingham was able to very quickly come up with a temporary version of a coude mounted spectrograph by combining a novel Littrow lens design with one of the gratings that was eventually destined for use on the UCLES instrument. It was the success of this project which meant they were able to obtain funds to later build the new instrument.  The original instrument was first housed in a large wooden box.

 The AAT was perfectly placed geographically and so was able to get onto observing this supernova very quickly. It has now been observed for many years and the campaign in radio, infra-red and optical continue to this day since 25 years is a long time to us – but rather infinitesimal in the scale of the universe.

So was it just luck? Being in the right place at the right time?

Personally, I don’t think so – I think it was having this amazing instrument up here at Siding Spring and a really innovative group of staff who were able to think outside the box and design instruments and obtain data on this incredible supernova explosion in a very short space of time. Luck may have been the SN going off nearby – but skill and dedication was what made all the difference.

 

SN1987a before and after by David Malin Anglo-Australian Telescope - used with permission

This photograph shows the field around the site of the supernova in great detail, both before the supernova exploded (right) and about 10 days afterwards, when it was still brightening. The image of the star that exploded to create the supernova is elongated. This does not necessarily indicate any peculiarity or a close companion, rather it is the effect of stars being by chance aligned along the line of sight. Several other examples can be seen in this picture and other, different, blended images are seen in the photograph of the same field taken two weeks after the supernova appeared (left). The pre-supernova plates were taken over about 90 minutes on the night of 1984 February 5, centred on the Tarantula nebula. The post-supernova plates (LHS image) were exposed for a total of about an hour on the night of 1987 March 8.

 The difference in image quality (‘seeing’) between these pictures is an effect of the Earth’s atmosphere which was much steadier when the plates used to make the pre-supernova picture were taken. Top left is NE. Width of each image is about 8 arc minutes. Text and Image © 1989-2010, Australian Astronomical Observatory, photograph by David Malin.

 

 

Planetary Alignments in the Evening Sky

Over the next 4 weeks, the solar system’s brightest planets will be putting on a spectacular evening show as they start to move into formation over the nights to come.

If you go out just after sunset and look towards the west, you will see Venus and Jupiter popping out of the twilight even before the sky has gone completely dark. After you have found them once or twice you will be able to find them earlier.   Seeing these two brilliant planets surrounded by darkening blue of the evening sky is a lovely sight.

If you go out at the next night, the view improves, because Venus and Jupiter are converging.  In mid-February they were about 20 degrees apart but by the end of the month, the angle narrows to only 10 degrees—so close that you can hide them together behind your outstretched palm.  Their combined beauty grows each night as the distance between them shrinks.

 A special night to look is Saturday, February 25th, when the crescent Moon moves in to form a slender heavenly triangle with Venus, Jupiter and the Moon as its vertices.  One night later, on Sunday, February 26th, it happens again.  This arrangement will be visible all around the world, from city and countryside alike.  The Moon, Venus and Jupiter are the brightest objects in the night sky; together they can shine through city lights, fog, and even some clouds.

 After hopping from Venus to Jupiter in late February, the Moon exits stage left, but the show is far from over.

 In March, Venus and Jupiter continue their relentless convergence until, on March 12th and 13th, the duo lie only three degrees apart—a spectacular double beacon in the sunset sky. Now you’ll be able to hide them together behind a pair of outstretched fingertips.

 There’s something mesmerizing about stars and planets bunched together in this way. This strange phenomenon is due to the fact that your eye works in much the same way as a digital camera does. In front, there is a lens which focuses the light and the retina acts like a photo-array behind the lens to capture the image of what you see. The retina is made up of rods and cones which are the organic equivalent of electronic pixels.

 There’s a tiny patch of tissue near the centre of the retina where cones are extra-densely packed. This is called “the fovea.” This enables you to see objects in high definition – it is critical to everyday tasks such as reading, driving and watching television. The fovea has the brain’s attention.

 The field of view of the fovea is only about five degrees wide. Most nights in March, Venus and Jupiter will fit within that narrow cone.  And when they do—presto!  It’s spellbinding astronomy.

Welcome to my new Blog Site!

Unfortunately thanks to malicious coders I have needed to remove the previous blog and now will start afresh. Here I will try to keep up to date news on what is happening in the skies – particularly for those of us Down Under and what is happening out in Space. 2012 promises to be a great year for astronomy.