Night Sky Watch for December

Written by David Pugh

Hi Everyone

Hope you are all keeping well.

First, breaking news. Last night I looked on-line for the latest on Comet Leonard that might get to mag 4 (i.e naked eye) this month. Turns out that it is starting to disintegrate! This is not unusual for a comet entering the inner Solar System where the Solar Wind and gravitational effects of the Sun are stronger. Still a shame though. However, to get a reasonable view of it you need to look about 3am - 6am low in the East. It is near Arcturus on Dec 6th.

For binocular users Mercury is only 4.2 degrees SE of Venus low in the SW at 5pm on Dec 29th but otherwise unremarkable this month. However, Venus puts on its best early evening show this month beaming brightly low in the SW in Sagittarius. A telescopic view will also show Venus displaying a large crescent. Venus is close to the crescent Moon on both Dec 6 and 7.

Mars is unfavourable this month but Jupiter (mag -2.2, disk 37") is still a brilliant evening sight in December in the SW on the Aquarius / Capricornus border. It is highest in the south around 5pm and does not set until 10pm. It lies 7 degrees W of the crescent Moon on Dec 9th and should make a nice sight. Through a telescope you could observe its 4 main moons or try for the Great Red Spot. The GRS will be central on the following evenings:- Dec 1st at 9.32pm, 2nd at 5.23pm, 4th at 7.03pm, 6th at 8.42pm, 7th at 4.33pm, 9th at 6.13pm, 11th at 6.32pm, 13th at 9.31pm, 14th at 5.32pm, 16th at 7.02pm, 18th at 8.41pm, 19th at 4.33pm, 21st at 6.12pm, 23rd at 7.51pm, 25th at 9.30pm (sad if you are observing then!), 26th at 5.32pm, 28th at 7.01pm, 30th at 8.40pm, and 31st at 4.32pm.

Saturn (mag +0.7, disk 16") is an evening object in Capricornus 17 degrees to the right of brilliant Jupiter. Early evening Dec 6th to 9th you can enjoy the trio of Jupiter, Saturn and Venus in a line along the Ecliptic.. A medium to large telescope will allow you to see Saturn's famous rings (tilted 20 degrees) and some of its moons.

Uranus (mag +5.7, disk 3.7") is in the evening skies in Aries. It is highest in the south around 9.30pm and sets at 5am.. Neptune (mag +7.9, disk 2.2") lies in Aquarius, about 3 degrees E of Phi Aquarii (mag +4.4). Its bluish "starlike" appearance should be visible in binoculars with a good star chart. or a goto telescope.

The Geminid Meteor Shower, which competes with the Perseids for being the best meteor shower of the year, peaks on Dec 13/14. Unfortunately this year a bright (79% lit) Moon will spoil the show until it sets around 3am. However, as the peak may be around 7am on the 14th, any early risers may be treated to a maximum hourly rate of 150 meteors between 3am and 7am. Wrap up warm for this!! You will also see some on other nights as Geminids can be seen from Dec 7 to 17th.

Beyond the Solar System all of the objects mentioned last month are still on view in the evening, if clear, but joined by early winter constellations. Our old friend the Pleiades star cluster M45 in Taurus is now very prominent in the SW mid evening. Binoculars or a small telescope are ideal for this, the brightest of all open or galactic clusters 410 light years away with its brightest stars spanning 2 degrees of sky.

Then overhead you could try for the trio of Messier open clusters M36,37 and 38, each some 10 times further away than the Pleiades (i.e some 4,000lys). Binoculars show each of these as hazy mag 6 objects but even a small telescope shows them nicely. It is interesting to compare them, M37 being the richest.

I hope to see many of you this thursday at the monthly meeting. I am looking forward to giving a talk on Barnard the famous american astronomer. I found this the most interesting of the talks that I prepared in lockdown, not least because, in my research, I was really surprised by his life story and hope that you will be too.

For those of you that cannot make thursday's meeting I wish you a happy Christmas and a healthy New Year.

Best Wishes