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The Sky at Night for December 2016

Events in DARK text happen during darkness. LIGHT text during daylight, i.e. we can't see them.

Note: Times are calculated for Liverpool and will vary slightly across the UK

Planet Date Rises ? Transits ? Sets ?
Planet Event ? Date Time Sun Angle ? Each month, we identify the best constellations to be seen from the UK between 9pm and 10pm.

This month we'll be looking for the winter constellations of Aries, Cetus, Perseus and Triangulum,
which can be found towards the south in the December night sky.

Night Sky in December

Aries - is the Latin word for "ram". It is the 39th largest of the 88 modern constellations and contains 2 bright stars, the brightest of which is Hamal. It is also one of the 12 signs of the zodiac, because the Sun and planets all pass through it, as viewed from the Earth. The best way to find Aries is to face South and locate the bright star Mira in the constellation of Cetus (see below), which will be about a third the way up from the horizon to the Zenith - the point right over your head. From there continue straight up to the next bright star, and that will be the central brightest star a line of 3 visible stars that mark out Aries.

Cetus - is named after a whale or sea monster that appeared in Greek mythology. It is the 4th largest constellation, and contains 3 bright stars and 12 dimmer ones. When looking towards Cetus we are looking away from the plane of our galaxy, the Milky Way, so our view is not blocked by the clouds of gas and dust normally found in spiral galaxies. As such, we can see many hundreds of distant galaxies behind the stars in Cetus, with each of those galaxies containing many millions of their own stars. To find Cetus, face south around 9pm, and look up and right a bit. The first bright stars you come across will most likely be part of the Cetus constellation, and you can use the above skymap to trace out all the other stars.

Perseus - is named after the Greek hero who destroyed a legendary monster called the Medusa - a monster that had hair made of snakes. In terms of size, it is the 24th largest constellation and is blessed with 5 bright stars, the brightest of which is Mirfak. Mirfak is known to be a giant star, some 62 times larger than the Sun and pumping out 5,000 times as much energy. The second brightest star, Algol, is actually two stars orbiting each other every 3 days, but because they are so close they look like just one. At this time of year, Perseus can be found right over the top of our heads at around 9pm, in a part of the night sky known as the Zenith.

Triangulum - is the Latin word for the shape it marks out in the night sky. It consists of three relatively dim stars that form a long, narrow triangle. Being a small constellation, it is only 78th largest and contains no bright stars, but should still be visible to the eye under a dark sky - i.e. no bright Moon around and away from streetlights. Look for it by finding Aries first (see above) and then look just above it for a small triangle.