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The night sky for February 2015

Northern Hemisphere

Ian Morison tells us what we can see in the northern hemisphere night sky during February 2015.

The constellation of Orion the Hunter is in the south in the evening, now a little towards the west. The three stars of his Belt point up towards Taurus the Bull, with its Hyades and Pleiades Clusters, and down towards Canis Major and the brightest of night stars, Sirius. Orion's top-leftmost star is the red giant Betelgeuse, and to its left are Canis Minor and the bright star Procyon. Above these stand the Gemini Twins, with the higher bright star of Castor and the lower of Pollux. Up and right of Gemini is Capella, a bright star in the constellation of Auriga, wherein binoculars also reveal the open clusters M36, M37 and M38. Leo the Lion rises in the east, and to the right of its bright star Regulus is the even brighter planet Jupiter, which outshines all the stars and other planets during the night.

The Planets


Southern Hemisphere

Claire Bretherton from the Carter Observatory in New Zealand speaks about the southern hemisphere night sky during February 2015.

Venus is stunningly bright for an hour after sunset, low in the west. Mars, though fainter, is higher up to its right at the beginning of February, but it gets lower each night until it slips into the evening twilight at the end of the month. Venus and Mars are only 0.4 degrees apart on the 22nd. Jupiter is low in the north-east in the evening, and crosses the sky just in time to set at dawn. This is because it is at opposition on the 7th, and so is on the opposite side of our sky from the Sun. As well as being due north around midnight, it means that the planet is at its closest to us and appears as big and bright as it ever can.

Jupiter lies in the constellation of Cancer, which contains just five stars that are visible to the naked eye. However, Cancer does host M44 - the Beehive Cluster - at its heart, which is to Jupiter's north. At magnitude 3.7, it is visible to the naked eye and is one of the closest open clusters to the Earth. Galileo studied it with his early telescope and found about 40 stars, and around 1000 are now known. The bright star Regulus, in Leo, is on the other side of Jupiter and marks the Lion's head and mane. Shining at magnitude 1.35, it actually comprises four stars arranged in two pairs. The double star Algieba (the Mane), below Regulus, was first split by William Herschel in 1782, and its separation of 4" is a nice challenge for modern observers with telescopes of 8 centimetres or more in aperture. Leo rises higher in the north as the night wears on, and it also contains the Leo Triplet, consisting of the interacting spiral galaxies M65, M66 and NGC 3628. At 35 million light-years away, these provide the opportunity to witness the gravitational dance of galaxies in the local Universe. All three show tidal disturbance, with NGC 3628 exhibiting a tidal tail 300,000 light-years long. The Leo Triplet appears near the bright star Denebola and about halfway between the stars Theta Leonis (Chertan) and Iota Leonis. While M66 is visible in large binoculars, the other two galaxies can be found using a small telescope. A group of at least eight galaxies is nearby, including M95, M96 and M105.

The constellation of Gemini is on the other side of Cancer to Leo, and its bright stars Castor and Pollux, representing the Heavenly Twins, can be seen in the north after sunset. Although Pollux appears brighter in our sky, Castor is a system of no fewer than six individual stars. Eta Geminorum, at the foot of the figure of Castor, is near to the open cluster M35. While just visible to the naked eye, this group of stars makes a lovely sight in binoculars or a wide-field telescope.

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The Night Sky This Month is one part of the Jodcast. The full show contains the latest news, interviews with astronomers, answers to listener questions and more.

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