Mortal as I am, I know that I am born for a day. But when I follow at my pleasure the serried multitude of the stars in their circular course, my feet no longer touch the earth - Ptolemy
Let's not ask for the moon ... we have the stars!!
- Charlotte Vale (Bette Davis) Now, Voyager (1942)
December is 31 days long and comes from the Latin word decem meaning ten. Dutch-born American astronomer and planetary scientist Dr Gerard Kuiper was born on 7 December, 1905. He discovered Miranda, a moon of Uranus; Nereid, a moon of Neptune, and many binary stars. Asteroid 1776 Kuiper, a crater on our Moon and the Kuiper Belt are all named in his honour. Dr Kuiper died in 1973.
Planet Hunting in the Morning
Venus is still the 'morning star' during December. Look to the east before the sun rises.
01: Saturn is a few degrees above the Moon just before dawn.
05: Again pre-dawn, catch bright Spica, the main star in the constellation Virgo 'the maiden', alongside the Moon, and then gaze at gorgeous planet Venus, which will be just north of Spica.
Geminids Meteor Shower
07–17: Geminids meteor shower.
On 14 December the Geminids meteor shower reaches its maxim. One of the finest, and probably the most reliable, of the major annual meteor showers presently observable, is helped this year by the waxing crescent Moon, which will have set by mid-evening on 14 Dec.
After moonset you'll be all-set for a dark night's meteor-hunt. Perhaps you'll be lucky, there's an expected shower of 120 meteors ZHR. DO wrap up warmly, several layers of clothing, hat, scarf, gloves, thick socks! Take along hot drinks in a thermos flask, and remember to take a torch. Yes, I know I sound like your Mum but you need to take care of your body on very cold nights so you don't suffer from exposure.
Mars rises just after twilight in December, it's in the constellation Gemini, just to the right of Castor and Pollux the 'twins'. The red planet outshines the brightest star in the sky - Sirius, in the constellation Canis Major. Mars will not be this close (56 million miles) to Earth again until 2016: this is called Opposition.
After Venus, Mars is the next easiest planet to identify. Even to the naked eye it's clearly orangy-red. Yes there are red stars like Aldeberan, the celestial 'eye of the Bull' in Taurus, but you can't mistake planets because they don't twinkle like stars do.
Planets (the name means 'wanderer') orbit the Sun like the Earth; each orbit takes their equivalent of a year (the further away from the Sun they are, the longer their year). Mars is further away from the Sun than us, so its year is longer, and its 'path' across our sky takes longer than Venus, which is closer to the Sun. But Mars appears to us to move much faster than the stars - the movement is obvious even from night to night - because it's so much closer to us than the stars we see from enormous distances.
Mars has two moons - which are possibly captured asteroids which ventured too close to the planet and got caught by its gravity. They're called Phobos and Deimos and they resemble the potatoes the Martian robotic creatures find so hilarious in that popular mashed potato advert.
Moon Phases - December 2007
Last quarter: 1 Dec
New Moon: 9 Dec
First quarter: 17 Dec
Full Moon: 23 Dec
Last quarter: 31 Dec
Future December Dates
Some Venus transits have occurred in December, in fact it's 'every other' time. Venus transits occur in pairs with an intervening gap of eight years and intervals of 121.5 and 105.5 years between the pairs of transits. A couple of dates for future diaries then: 11 December, 2117 and 8 December, 2125.
- Discuss astronomy at the A413876