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April 2012: Fooling No-one

April 2012

In the show this month, Megan rounds up the latest news and we find out what's in the April night sky from Ian Morison and John Field. This show is shorter than usual because all the Jodcasters were kept so busy by the National Astronomy Meeting (NAM) at the end of March, so if your appetite for interviews is not sated then please listen to our daily reports from the first, second, third and fourth days of NAM.

The News

In the news this month:

The Night Sky

Northern Hemisphere

Ian Morison tells us what we can see in the northern hemisphere night sky during April 2012.

The constellation of Orion is in the west after sunset, below Taurus, which contains the Hyades and Pleiades Clusters. Above is the bright yellow star Capella in the constellation of Auriga, which sits beside open star clusters along the plane of the Milky Way. Castor and Pollux, the Twins, are to the left in Gemini. Leo is fairly high in the south later in the evening, with its bright star Regulus. Virgo is down and to the left, with its bright star Spica. Between Spica and the back of Leo is the Realm of the Galaxies, where a telescope will show a number of galaxies on a dark night, including M84 and M87. The bright star Arcturus is nearby, in Boötes, while the arc of Corona Borealis, the Northern Crown, is to the left. Ursa Major, the Great Bear, is almost overhead in the north, and contains the asterism of the Plough. The middle star of the Plough's handle is a double, called Alcor and Mizar, which can be distinguished with the naked eye under a dark sky, or with binoculars. The brighter of the two, Mizar, can itself be seen to be a double when using a small telescope. Hercules rises in the east late in the evening, near to Lyra, with its bright star Vega. Hercules contains the globular cluster M13, which is on the right of the Keystone, an asterism of its four brightest stars.

The Planets


Southern Hemisphere

John Field from the Carter Observatory in New Zealand speaks about the southern hemisphere night sky during April 2012.

Venus is low in the north-west at dusk, shining brilliantly until it sets about two hours after the Sun. A telescopes will show it to be a crescent, and it is now moving towards inferior conjunction (in front of the Sun as seen from Earth). Jupiter is even lower in the west, and is briefly visible at twilight as it approaches conjunction (behind the Sun as seen from Earth). Mars gets midway up in the north, shining orangey-red and near to Leo's brightest star, Regulus. It is now moving away from us, but a telescope will still show its disc. Saturn appears yellowy, midway up the eastern sky at dusk and below Virgo's brightest star, first-magnitude Spica. It gets high in the north by midnight. With a telescope, Saturn's rings, its surface bands and its orangey largest moon, Titan, may be seen.

Far from the Milky Way, Virgo is a good constellation in which to spot galaxies. 10° west of Spica is the Sombrero Galaxy, visible through binoculars at magnitude +9 and with discernible features when using a medium-sized telescope. Above Spica is a small, kite-shaped constellation called Corvus, the Crow. In Greek mythology, the Crow, or Raven, was banished to the sky by the Sun god Apollo for failing to bring him a cup of water. Its two brightest stars are around magnitude +2.6, while Delta Corvi is a wide double star. Nearby is Hydra, the Water Snake, the largest of the 88 modern constellations. It has five stars forming its head and a long path of stars making up its body. M83, the Southern Pinwheel Galaxy, is one of the few objects to be found within it. It has a magnitude of +7.5, allowing it to be seen through binoculars, while a telescope will reveal its spiral structure.

The winter constellation of Scorpius rises in the eastern sky in the evening. Its brightest star is the red giant Antares, meaning Rival of Mars. Named for its hue, it can currently be compared to Mars as they appear in the sky at the same time. Since New Zealand does not contain scorpions, to the Māori Scorpius was Te Matau a Māui, the Hook of Māui. The mythological figure of Māui used this Hook to fish the North Island of New Zealand out of the ocean. The Hook was the jaw bone of one of his ancestors, and Antares, or Rehua, represents his blood which he placed on the Hook. When a giant fish was pulled up and became the North Island, the Hook flew into the sky. The North Island was then named Te Ika a Māui, the Fish of Māui.

Show Credits

News:Megan Argo
Night sky:Ian Morison and John Field
Presenters:Libby Jones and Christina Smith
Editors:Mark Purver, Megan Argo, and Claire Bretherton
Segment Voice:Cormac Purcell
Website:Libby Jones and Stuart Lowe
Producer:Libby Jones
Cover art:Mercury's northern volcanic plains, imaged by the MESSENGER spacecraft and coloured according to surface height with the highest points in white and the lowest in purple. CREDIT: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/Brown University

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