The night sky for February 2009

ROG Opening Times

Important Notice for the 31 December: The Royal Observatory North (Flamsteed House) and Meridian Line will open to the public at the later time of 11:30. The Astronomy Centre and Planetarium will open as normal at 10:00.


The image above shows the skies above Greenwich around 10pm on the 15th February, taken from Edwin Dunkin's 'The Midnight Sky'. This view is facing south with the Royal Observatory in the centre.

The wonderful constellation of Orion dominates the winter skies and can be seen from first darkness towards the southern part of the sky throughout February. Orion represents a hunter, and can easily be spotted by the three bright stars that make up his belt, seen in the centre right of the image above. Just below these belt stars, in Orion's sword, you may be able to spot a small fuzzy patch called the Orion Nebula. It doesn't look like much to the naked eye, but as this image shows, with a large telescope the sight is amazing.


The Orion Nebula is a region of star formation in our own Galaxy, a huge cloud of gas and dust being pulled together by gravity into clumps, which get denser and denser and hotter and hotter until nuclear reactions begin, and a new star is born.

We can see a group of young stars, formed within the last 100 million years, if we follow Orion's belt to the right, past the bright red giant star, Aldeberan (the eye of Taurus the bull) and on to a small cluster of stars called the Pleiades. The Pleiades are also known as the Seven Sisters, because the seven brightest stars stand out most clearly in the night sky. In fact the Pleiades contains over a thousand stars, which all formed together from a single cloud of gas and dust. Over time the Pleiades stars will gradually move apart, spreading out into space.

In the constellation of Orion itself we see some older stars, heading towards the end of their lives. Towards the bottom right of Orion is hot blue Rigel, a blue supergiant star, 17 times more massive than the Sun. In the opposite corner is cool, red Betelgeuse, a star which has cooled and bloated out so much that if it was placed at the centre of the Solar System, it would reach out as far as the orbit of Jupiter. Some day soon, Betelgeuse will end its life in a massive explosion called a supernova. Of course in astronomy, soon can be a very long time, but Betelgeuse could go bang within our lifetimes, and really would be a spectacular sight, brighter than a crescent moon in the sky.

Following Orion's belt to the bottom left we find the brightest star in the night time sky, Sirius, part of Orion's hunting companion Canis Major, giving it the alternative name, the Dog Star. Sirius is actually a binary star system consisting of a white main sequence star and a small, faint white dwarf.

As well as these fantastic winter objects, there are also some planets to be seen in the sky this month. First of all, the unmistakable Venus, visible towards the south west in the evening skies throughout February. Venus is so bright you can really only mistake it with the headlights of an aeroplane, and is at its brightest on the 19th of February. It should be above the horizon until around half past nine throughout the month.

Rising later in the evening, in the constellation of Leo, is Saturn. By the end of the month it will be rising in the East by around 6:30. Saturn is normally a stunning sight through a small telescope, with its amazing rings, but at the moment we observe these almost edge on, so they are very difficult to spot.

In the morning skies you may just spot Mercury, although it will almost be lost in the twilight. On the 13th February it reaches its greatest elongation, the maximum apparent distance from the Sun in the sky.