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January 2013: Seven!

January 2013

Seven! In our seventh birthday show, we talk to Professor Joanna Haigh about the effect of the Sun on climate change, Stuart rounds up the latest news and we hear what we can see in the January night sky from Ian Morison and John Field.

The News

In the news this month: the youngest young stellar objects, stellar sibling rivalries and planets go missing.

Interview with Prof. Joanna Haigh

Professor Joanna Haigh researches atmospheric physics at Imperial College London and is particularly interested in the effect of the Sun on the Earth's climate. In this interview she talks about solar variability, how it manifests itself in the Sun and how it affects temperatures and wind velocities in localised regions of the Earth's atmosphere. She discusses the history of solar and atmospheric observations and the modern methods of measurement. She also talks about her current research into the impact of the Sun's ultraviolet radiation on ozone gas in our atmosphere, and tells us why we can't pin the blame on the Sun for recent global climate change.

The Night Sky

Northern Hemisphere

Ian Morison tells us what we can see in the northern hemisphere night sky during January 2013.

Orion is prominent in the evening sky. Following the line of his Belt upwards, you reach Taurus. The Hyades Cluster and the nearer star Aldebaran are located here. The Pleiades Cluster is a little further up. Following Orion's Belt downwards brings you to Sirius, the brightest star in the night sky. The open cluster M41 is a few degrees below Sirius. The little-known constellation of Monoceros is to Orion's left, containing little except the Rosette Nebula and the nearest known black hole to Earth (though only one of these two is visible to ordinary telescopes!) Up and to the the left of Monoceros is the star Procyon in the constellation of Canis Minor. Pollux and Castor, the heads of the Gemini Twins, are above Procyon. Close to the legs of the higher Twin is M35, an open cluster. Continuing on, we reach Auriga, which hosts the bright star Capella and the open clusters M36, M37 and M38. Moving down from Pollux, through Castor, brings us to the constellation of Cancer. The Beehive Cluster lies here, and is spectacular through binoculars.

The Planets


Southern Hemisphere

John Field from the Carter Observatory in New Zealand speaks about the southern hemisphere night sky during January 2013.

Jupiter continues to travel through Taurus and is gradually dimming as it moves away from the Earth, while the constellations of Orion and Canis Major are nearby in the northern sky. The head of the V-shape of Taurus is the Hyades Cluster, which appears along with the red star Aldebaran. The Pleiades Cluster, marking the Bull's back, is to the west of the head. Gemini and Cancer are also in the southern sky. The bright stars Castor and Pollux form the heads of the Gemini Twins, and are found in the north-east after sunset. Gemini is at the edge of the Milky Way, and near to Castor are five faint and distant galaxies which can be viewed using a large telescope. The open star cluster M35 is near to the star Eta Geminorum, and can be seen with the naked eye. Binculars or a small telescope reveal the detail of individual stars. Cancer contains five bright stars and the open cluster Praesepe, or the Beehive, at its centre.

Orion dominates the summer sky. Below the three stars of Orion's Belt is Orion's Sword, with the Orion Nebula at its heart. This looks like a fuzzy star to the unaided eye, but binoulars or a small telescope reveal a bat-shaped cloud. A telescope with an aperture of 100 millimetres allows stars to be seen in and around the nebula, including the four stars known as the Trapezium. The brightest of these is illuminating the nebula with its ultra-violet radiation. Orion's left foot is Rigel, the constellation's brightest star, while his right shoulder is Betelgeuse, the second-brightest. To the east are the Hunting Dogs, Canis Major and Canis Minor, the larger of the two constellations containing Sirius, the brightest star in the night sky. Procyon marks the tail of the Smaller Dog. Halfway between Betelegeuse and Procyon lies the Rosette Nebula, which contains a rectangular cluster of stars. The second-brightest night-time star, Canopus, is almost overhead in the evening sky.

The Planets

Odds and Ends

Brian May's first paper since the publication of his thesis has been published on modelling infrared emission from zodiacal dust. Zodiacal dust is dust scattered along the zodiac and is what causes the zodiacal light. They have been modelling this in the infra-red emission using IRAS and COBE. They found that the majority of the dust comes from comets and asteroids with a small component of interstellar dust.

Tau Ceti, a star 12 light years away, has just been shown to have a planetary system of 5 planets including one potentially in the habitable zone. These planets have been discovered using the radial velocity method where tiny shifts in the star's spectra are observed and, in this case, modelled. The 5 planets range in mass from 2 to 7 Earth masses with, assuming circular orbits, orbital periods between 14 and 640 days.

NASA deliberately crashed two of its spacecraft into the Moon on the 17th of December. Ebb and Flow, the twin probes of the GRAIL mission, had spent the previous 90 days mapping the distribution of mass in the Moon by flying in formation over its surface. NASA decided on a controlled impact at the end of their mission, and sent the two craft - each with a mass of about 200 kilograms - into a lunar mountain at 6000 kilometres per hour.

Show Credits

News:Stuart Harper
Interview:Prof. Joanna Haigh and Mark Purver
Night sky:Ian Morison and John Field
Presenters:Libby Jones, Mark Purver and Christina Smith
Editors:Christina Smith, Claire Bretherton, Stuart Harper and Mark Purver.
Segment Voice:Cormac Purcell
Website:Christina Smith and Stuart Lowe
Producer:Christina Smith
Cover art:Zodiacal Light over La Silla. CREDIT: European Southern Observatory's photostream, Flickr

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