EYES ON THE NIGHT SKY - DECEMBER 2019
Welcome to December’s edition of Eyes on the Night Sky. This time of year, the nights are the longest, allowing you to enjoy the stars at a sensible time of night or spend more time enjoying the fresh air and the wonders of our night skies. Please remember to wrap up warm when outside and be well prepared if traveling to remote locations to stargaze. This month, there are a couple of meteor showers to watch out for, a beautiful Christmas conjunction and a young nebula to discover.
Milky Way, Andromeda Galaxy and a Meteor. Credit: Sam Price
On the night/early morning of 13th and 14th December, the Geminid Meteor Shower will peak, producing bright and fast ‘shooting stars’. Despite the Moon being in its waning gibbous phase, or one day from full (94%), it’s worth keeping an eye out for the brighter meteors.
The radiant of this meteor shower originates right by the star Castor in the constellation of Gemini and is known to be cometary debris from 3200 Phaethon. Earlier in the evening, you could watch out for a rare phenomenon called ‘Earthgrazers’ – where the constellation of Gemini is close to the horizon and the meteors skim over the top of the Earth’s atmosphere, causing a spectacular, colourful and long trail. Once the constellation rises higher into the atmosphere, you will see more ‘ordinary’ meteors. These travel at around 80,000 miles (130,000 km) per hour and burn up 60 miles (100 km) above Earth’s surface.
If you would like to observe a second meteor shower this month, the Ursid Meteor Shower peak occurs on the night/early morning of 22nd and 23rd December. The radiant of this meteor shower is situated in the constellation of Ursa Minor. The waning crescent Moon at 10% will rise at 5am, which will provide a dark enough sky to see the meteors, which is debris from the Comet 8P/Tuttle. There are normally a low 10 meteors per hour during the peak, but this shower has produced some surprises with previous years having an outburst of more meteors than expected.
The Full Moon is on 12th December and the New Moon occurs on 26th December. The Winter Solstice falls on 22nd December, where the Earth’s North Pole is tilted furthest away from the Sun which heralds the start of winter.
The Moon will feature in a very pleasing conjunction on 28th December, where from around 5pm, or when darkness falls, the thin, waxing crescent Moon with Earthshine can be seen sitting 5 degrees below Venus, low on the horizon. This conjunction will occur again the following night at the same time but the Moon will sit around 6 degrees apart from Venus but will lie eastwards. Venus is the dominant planet for this month; you’ll see it emerge into the sky at in a higher position each evening throughout the month.
A Young Nebula
Crab Nebula (M1) Image Credit: NASA, ESA, J. Hester, A. Loll (ASU)
The Crab Nebula (M1 is an interesting challenge for telescope owners. The Crab Nebula is a relatively new one that was discovered only a thousand years ago by the Chinese. In 1054 AD, they noticed a very bright, new star that blazed brightly even throughout the day for three weeks. It was present in the night sky as a star for just around two years before it vanished completely. In 1921, it was discovered that the ‘star’ didn’t vanish; it was a massive supernova which blew completely apart, leaving gaseous remnants that expanded, forming the nebula we know today.
The Crab Nebula was named by the English astronomer, third Earl of Rosse in 1844 and is situated in the constellation of Taurus and lies around 6500 light years away from us. In a dark sky and away from light pollution, it can be observed through a 3 inch telescope as a grey oval smudge. The nebula starts to take shape and even filamentary detail can be seen through telescopes of 12 inches of aperture and larger.
Pleiades Star Cluster
Pleiades Star Cluster. Image creditNASA/JPL-Caltech)
Whilst in the vicinity of the constellation of Taurus, use your binoculars to view a stunning star cluster. Called the Pleiades Star Cluster, or the Seven Sisters, these comparatively few, bright and stunning stars comprises 800 in this open cluster and is situated 410 light years from Earth. A challenge for the keen sighted is to see how many stars can be seen with the unaided eye. Due to light pollution, most people can see six stars, even in a comparatively dark sky. But 12 stars have been seen in exceptionally dark skies and most probably be difficult to see in these modern times, sadly due to the increase in air pollutants and background sky glow from the world’s cities. These young, hot and extremely bright stars light the gasses and dust that they were born from and this nebulous cloud can be spotted in telescopes of 8 inches and upwards.