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The February 2012 night sky

by Clive Jackson [email protected]

Clive Jackson is the Director of the Astronomical Observatory of Tavira (Sitio do Malhão, Tavira) and the Camera Obscura (next to the Castle in Tavira), specialising in education and public outreach.

Welcome to the February night sky. This month we have an extra day to enjoy, as 2012 is a leap year. Every four years we have a 29th of February. This is necessary to keep the calendar in step with the seasons.

Shortly after sunset over in the west, Venus is still dominating the evening sky; this planet is in the constellation of Pisces at the moment, and the thin crescent Moon will be close to Venus on the 25th.

The gas giant planet Jupiter is also seen this month high in the west soon after sunset. This planet is at a greater altitude in the sky than Venus and it is easy to tell them apart as Venus shines with a sparkly white light and Jupiter glows a golden yellow colour. Jupiter is in the constellation of Aries and the crescent Moon is near to it on the 26th.

Just before midnight in February over in the east can be seen rising the red planet Mars. It is in the constellation of Leo and the Moon, two days past full, is near to Mars on the 9th.

The constellations of Taurus and Gemini are overhead during the evenings this month, and close by them is the constellation of Auriga the Charioteer, with its bright yellow star called Capella.

This is the sixth brightest star in the night time sky and it is 160 times more luminous than the Sun and 45 light years away. You should not easily confuse Jupiter with Capella as Jupiter is much brighter.

During the last week in February, it may be possible to spot the elusive planet Mercury very close to the western horizon just after sunset. This planet would look like a faint pink coloured star and on the 22nd the very thin crescent Moon will be close to Mercury aiding its identification.

At sunset, over on the northern horizon, the bright stars Vega and Deneb are setting. Between these two stars is a small area in the sky that is currently being searched by the Kepler Space Telescope.

This instrument is specifically designed to find planets orbiting distant stars (called exoplanets). Up until now 2,326 candidates have been detected, although it is too early to confirm all of them.

The interesting thing is that due to the method of scanning it can only detect 10% of the planets that could be there. So, potentially, there could be 23,000 planets in this area of the sky.

Now, if you take into account that only 1/400th of the sky is being looked at, it means that around 10 million planets potentially exist there. And when you also take into account that this instrument can only detect planets inside a small volume of space and this volume of space represents less than 1% of the volume of our galaxy.

So, by simple arithmetic, it can be calculated that there are at least a thousand million planets in our galaxy. These numbers can be relied on as they are based on observational data. In fact, they represent the minimum number of planets, there may well be many times more.

The Moon is full on the 7th, last quarter on the 14th and new on the 21st.

To contact Clive Jackson call 281 322 527, fax 281 321 754, email [email protected] or visit

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