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December 2014: Icy

December 2014

In the show this time, we talk to Professor Elisa Resconi about detecting neutrinos with IceCube, Ian Harrison rounds up the latest news and we find out what we can see in the December night sky from Ian Morison and Claire Bretherton.

The News

In the news this month: a comet landing, dodging black holes and dust-free comets.

Interview with Prof. Elisa Resconi

Professor Elisa Resconi studies ghostly particles called neutrinos at the Technical University of Munich, using the IceCube detector at the South Pole. She talks about research at the boundary of particle physics and astrophysics, and discusses the mystery of the ultra-high-energy neutrinos that seem to originate far out in the Universe. She describes the instrument, which comprises a cubic kilometre of very pure ice and detectors that pick up Cherenkov radiation, and she talks about the known types of neutrino and the possibility of a sterile neutrino that could constitute dark matter. Prof. Resconi also tells us about the scientists, engineers and doctors who spend winters in Antarctica, operating IceCube while physically isolated from the rest of the world.

The Night Sky

Northern Hemisphere

Ian Morison tells us what we can see in the northern hemisphere night sky during December 2014.

During the later evening, the Great Square of Pegasus is setting towards the west, with the constellation of Andromeda above and to its left. The W-shape of Cassiopeia is higher still, with Perseus just below and the Perseus Double Cluster between them. Below Perseus is Auriga, containing the bright star Capella, while Orion the Hunter is rising in the south-east. The three stars of Orion's Belt point down to Sirius, the brightest night-time star. Taurus the Bull is between Orion and Perseus, hosting the open clusters of the Pleiades and Hyades, as well as the red star Aldebaran, which appears to be part of the Hyades but is actually just lying along the same line of sight from Earth. Gemini is to the left of Orion, with the stars of Castor and Pollux representing the Twins. Rising later are Cancer, home to the Beehive Cluster, and Leo, the current residence of the planet Jupiter.

The Planets


Southern Hemisphere

Claire Bretherton from the Carter Observatory in New Zealand speaks about the southern hemisphere night sky during December 2014.

The nights are at their shortest on the 22nd and the night sky is dominated by the constellations of Taurus, Orion, Canis Major and Canis Minor. In Greek mythology, Orion the Hunter is the enemy of Scorpius the Scorpion, and so the two appear on opposite sides of the sky. The figure of Orion appears upside-down to southern hemisphere observers. The line of three stars forming his Belt are historically known in Aotearoa (New Zealand) as Tautoru, and his Sword and Belt together are sometimes seen as a pot or saucepan. Prominent in the middle of the Sword is the Orion Nebula, M42, a star formation region that looks like a fuzzy star to the naked eye but a beautiful region of nebulosity and young stars in a telescope or binoculars. At its heart is the Trapezium Cluster, a tight group of stars whose ulraviolet radiation makes the surrounding gas glow. The reflection nebula M78 can also be found in Orion using a small telescope, and the Horsehead Nebula, a dark region in the bright nebula of IC 434, lies south of the star Alnitak in Orion's Belt. The blue-white supergiant Rigel, at the top-left, is the brightest star in Orion, while the aging red giant Betelgeuse, at the bottom-right, is the second-brightest.

Following Orion's Belt to the right leads to Sirius, known to Māori as Takurua, which is the brightest star in the night sky. It is in Canis Major, the larger of Orion's two Hunting Dogs, and Canis Minor, the Smaller Dog is lower down, near the eastern horizon in the later evening. The brightest star in Canis Minor is Procyon, which is actually a binary system consisting of a main-sequence star and a white dwarf companion. To the left of Orion's Belt is the V-shape of stars representing the head and horns of Taurus the Bull. The Hyades Cluster resides here, and is one of the closest open star clusters to the Earth. Continuing around the sky, the Pleiades Cluster is another open cluster full of young, blue stars. In New Zealand it is called Matariki, meaning Little Eyes or Eyes of God, and its first pre-dawn appearance in June marks the start of the Māori year. The Milky Way stretches through these constellations and along the southern horizon, and along this line is the constellation Crux, currently low in the south-east later in the night. Beside it is the dark Coalsack Nebula, an interstellar cloud of gas and dust that obscures the stars beyond. To Māori it is Te Pātiki, the Flounder.

The Planets


Odds and Ends

Astronomers have discovered the first multiply-imaged gravitationally lensed supernova. Gravitational lensing is a phenomenon arising from Einstein's General Relativity, in which light is bent around massive objects. In this case, a spiral galaxy is lensed by a cluster of galaxies, producing three images. One of those images has been further lensed by a foreground galaxy, so four images of the supernova could been seen. The path difference between the light rays means there is a time delay between the images. This allows astronomers to measure the amount of luminous and dark matter in the galaxy, and could also potentially allow for an absolute measurement of the Hubble constant. It is predicted that the we will see the supernova in another image of the spiral galaxy in about a year.

A new physics paper has estimated the chances of complex life falling victim to gamma-ray bursts (GRBs). Although somewhat mysterious, long-duration GRBs are thought to originate from supernovae, and are incredibly intense flashes of gamma- and X-rays that last for days but do not recur. Such a burst, even several thousand light-years from a planet, could alter its atmosphere and disrupt the ecosystem enough to cause extinctions of complex life forms. Among other things, the authors suggest that everything within 4 kiloparsecs of the centre of the Milky Way is highly likely to have been subject to a lethal GRB over the last 500 million years, and that even the Earth, at twice that distance from the Galactic centre, had a 50% probability of such an event affecting it over the same period.

A joint venture between the European Space Agency and LEGO has been announced to create a robotics course called ExoPREP. ExoPREP will be focussed on space science and technology specifically related to the ExoMars mission. The course will be available in 2015 across the EU.

Show Credits

News:Ian Harrison and Christina Smith
Interview:Prof. Elisa Resconi and Mark Purver
Night sky:Ian Morison and Claire Bretherton
Presenters:Mark Purver, Christina Smith and Hannah Stacey
Editors:Ben Shaw, George Bendo, Claire Bretherton, Monique Henson, Mark Purver and Prabu Thiagaraj
Segment Voice:Tess Jaffe
Website:Christina Smith and Stuart Lowe
Producer:Christina Smith
Cover art:The IceCube neutrino observatory. CREDIT: Eli Duke

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