December 2009: Live!

Live! After months of talking about it we finally recorded an episode (the first of two) with a live audience made up of Jodcast listeners. We start with our now traditional December pantomime - Jenaddin. In the show we have an interview with Dr Chris Lintott (University of Oxford) about the latest news from the Galaxy Zoo project. As ever we have the latest astronomical news, what you can see in the December night sky, your feedback and other odds and ends. Various Jodcast listeners have been adding their photos from Jodcast Live to the Jodcast Flickr group (maintained by Jodatheoak).

The News

In the news this month:

• When massive stars explode as supernovae, they leave behind a dense, compact object: either a neutron star or a black hole depending on the mass of the original star. They also produce an expanding shell of debris known as a supernova remnant. Many of these shells are known in the Milky Way, but compact objects are not detected in all of them. One object in particular, the remnant known as Cassiopeia A has been expanding since its progenitor star exploded about 330 years ago, but for a long time no compact object was detected, despite many searches. Then, in 1999, observations from the Chandra X-ray Observatory showed X-ray emission coming from the centre of the remnant. But, the emission characteristics of the object did not match what astronomers expected to see from a neutron star or black hole, so its nature remained uncertain. Now, two researchers think they know why... (full paper in Nature).
• Planet searching techniques are continuously being refined and are detecting ever smaller planets at greater and greater distances from their parent stars. But a team of astronomers have discovered a link between planetary systems and lithium abundance that could provide a new tool in the search for exoplanets. Most methods of searching for planetary systems around other stars are best suited to finding large planets orbiting very close to their host stars. But what if there was a way to determine the likelihood of a particular star hosting planets, without actually detecting the planets at all? A team, led by Garik Israelian of the Instituto de Astrofisica de Canarias in Tenerife, think they have found a link between whether stars host planets and how much lithium is observed.... (full paper in Nature).
• The constellation of Orion contains some massive complex regions of star formation, the most obvious of which is the Great Orion Nebula, M42, located in Orion's sword. Through an optical telescope you can see a large glowing cloud of gas illuminated by a cluster of young, hot stars. But behind this cloud, hidden from view, lies another cluster of proto-stars, clumps of gas still collapsing under gravity in the process of forming stars. As ordinary light cannot penetrate through the gas, other parts of the electromagnetic spectrum are needed to see these proto-stars. Luckily, radio waves can penetrate through the thick gas and dust and can provide images of these stars in the process of formation. Using the Very Long Baseline Array, a collection of ten radio telescopes located across the USA, a team of astronomers has peered into this hidden region and imaged it at high resolution... (full paper accepted to the Astrophysical Journal).
• And finally: in a press briefing on November 14th, members of the LCROSS team presented the latest results from the impact of the spacecraft on the Moon back on October 9th. The Lunar CRater Observation and Sensing Satellite was one of two man-made objects to impact the Moon that day. The ejecta cloud produced by the empty Centaur upper stage of the rocket created a plume of material which was imaged by an infra-red camera on board the LCROSS probe which was following four minutes behind...

Zookeepers

It has been a while since we had an update on the massive, online citizen science project Galaxy Zoo so we invited Dr Chris Lintott (University of Oxford) to Jodrell to tell us the latest news in front of a live audience. Amongst other things, we hear about the discovery of green peas (also red peas, i-peas and pea-js) and the new cosmic mergers project.

The Night Sky

Ian Morison tells us what we can see in the night sky during December 2009.

Northern Hemisphere

Soon after sunset over in the west you can see Cygnus the Swan, Lyra the Lyre and Aquila the Eagle. Further around to the south is the Square of Pegasus. Up to the left of that is Andromeda and below that the circlet of Pisces. Higher up in the sky is the w shape of Cassiopeia and down to the left of that is Perseus. Between them is the double cluster and it can be seen as a fuzzy glow in binoculars. As the night progresses, over to the south-east and east, Taurus the Bull can be seen with Orion seen rising at about 10pm.

The Planets

• Jupiter, now lying in Capricornus, is still easily visible in the south-west after sunset. During December, its magnitude drops very slightly; from -2.2 to -2.1. It has an angular size of 37.3 arc seconds at the beginning of the month so a small telescope will show much detail on the surface if seeing conditions are good. It is moving towards Neptune which is just 0.6 degrees away to the north on the 20th of the month. On the 21st, a thin waxing crescent Moon will pass just three degrees above them.
• Saturn can now be seen in the pre-dawn sky when, as December begins and at magnitude +1, it will rise at about 01:30 UT. By December's end it will be rising at 11:30 UT and so will be high in the South before sunrise. The angular size of the disc increases from 17 to 18 arc seconds during the month.
• Mercury reappears into the evening sky in the latter part of December and may then be spotted low above a clear southwestern horizon.
• Mars is becoming prominent in the late evening sky, rising at about 20:30 UT at the begining of the month. It will be well up in the south-east by midnight and is due south and thus highest in the sky in the early hours of the morning.

Highlights

• The early morning of December 14th will give us the chance, if clear, of observing the peak of the Geminid meteor shower. Happily, this year, the Moon is just two days before full moon and so its light will not intrude! You could see more that 60 meteors an hour in the early hours of the morning when Gemini is high in the sky! An observing location well away from twos or cities will really pay dividends though.
• At about 7-8pm on the 21st December, the Moon, a day before first quarter, is just over 3 degrees up to the right of Jupiter. Neptune, at magnitude 7.9, lies between them and is just 0.6 degrees to the upper right of Jupiter.Neptune will be easier to spot on the days before and after when the Moon is not so close in the sky.
• In the early evening of December 31st the Moon undergoes the smallest partial eclipse that we have seen in the UK for 40 years - in that the Moon will only just dip into the umbral shadow of the Earth. At mid-eclipse (19:23 GMT) the lower right of the Moon may just be seen to have a faint ruddy colour. The Moon begins to enter the penumbral shadow at 17:17 GMT, and will thus begin to darken. A small part of the Moon at its lower right enters the umbral shadow at 18:52 GMT and leaves it at 19:52 GMT.

Southern Hemisphere

The brightest star you can see in the sky is Sirius which is in the east in the early evening. Its temperature is about 9500 C and it is about 26 times more luminous than our Sun. Canopus is about 15 degrees higher up and further around to the south. It is a supergiant star and is about 13,000 times brighter than the Sun. Achernar is just above the south celestial pole and is the ninth brightest star in the sky.

Odds and Ends

There will be another Twitter Meteor Watch for the Geminid meteor shower led by the Newbury Astronomical Society (@NewburyAS on Twitter). Follow #Meteorwatch on Twitter for live updates and photos between the 12th and 14th December.

The Galloway Forest Park in Scotland has become the UK's first Dark Sky Park. A park in Hungary was also designated as a Dark Sky Park at the same meeting of the International Dark Sky Association, bringing the total number of European Dark Sky Parks to two.

There is a night sky simulator at need-less.org.uk to show how dark the sky is across the UK. There is also a petition about light pollution going to the Welsh Assembly.

ESA's Rosetta spacecraft had it's third and final fly-by of the Earth on the 13th November and sent back some amazing photos of the Earth. Rosetta is now on it's way to Comet 67P/Churyumov-Gerasimenko in the outer Solar System.

The Atlantis space shuttle took worms and butterflies to the International Space Station as part of mission STS-129 in November.

The stuck Spirit rover on Mars finally moved on the 19th November!. While it only moved 12 millimeters foward, this is better than expected! We showed this picture of the test rover on the big screen.

NASA's Be A Martian website allows you to explore the Martian surface and sort through images to get a more complete map of the planet.

ESO's ALMA (Atacama Large Millimeter/submillimeter Array) had it's first fringes - the first time two antennas have worked together. Dave thought he spotted two TARDIS (what is the plural?) in one picture.

The Large Hadron Collider at CERN has restarted. Listener Paul Miyagawa who works at CERN was at Jodcast Live and gave us an update.

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