SkyEye

Welcome to SkyEye, your guide to this month's celestial events.

December 2008

All times and dates are given in Universal Time (UT).
Nightly darkness estimates are calculated for 45° N and 30° S.
Like total solar eclipses, lunar occultation events can be seen only from limited regions on Earth (and sometimes not at all if the occultation takes place during daylight hours). However, the Moon will appear close in the sky to its "target" for some hours either side of the actual occultation, regardless of where you are.

Date		Event
1	Mon	Moon occults Venus: visible from the north Atlantic and western Europe from about 15:00 UT.
2	Tue
3	Wed
4	Thu	2 Pallas at opposition
5	Fri	First Quarter Moon
5	Fri	Mars at conjunction
6	Sat	The waxing gibbous Moon is not ideal for viewing the Phoenicid and Puppid-Velid meteor showers.
7	Sun
8	Mon
9	Tue
10	Wed	Uranus at east quadrature
11	Thu
12	Fri	Full Moon
12	Fri	Moon at perigee: Because Full Moon occurs so close to perigee, expect high tides.
13	Sat	The Geminid meteor shower is wiped out of the nearly Full Moon.
13	Sat	Saturn at west quadrature
14	Sun
15	Mon
16	Tue
17	Wed
18	Thu
19	Fri	Last Quarter Moon
20	Sat
21	Sun	Solstice
22	Mon	Unlike the other major meteor showers this month, the Ursid meteor shower is not too badly hampered by moonlight.
23	Tue
24	Wed
25	Thu	Moon occults first-magnitude star Antares: visible from western Africa from about 6:00 UT.
26	Fri	Moon at apogee
27	Sat	New Moon
28	Sun
29	Mon	Moon occults Jupiter: visible from parts of the Southern Ocean and Antarctic from about 8:00 UT.
30	Tue
31	Wed

The Solar System

The word planet is derived from the Greek word for "wanderer." Unlike the background stars, planets seem to move around the sky, keeping mostly to a narrow track called the ecliptic, the path of the Sun across the stars. Dwarf planets and small solar-system bodies including comets, are not so constrained, often moving far above or below the ecliptic.

Sun: Ophiuchus -> Sagittarius
Although Ophiuchus is not a member of the zodiac, the ecliptic passes through it. A solstice occurs on Earth on 21 December The word solstice means "sun stands still" so that on this day, the solar declination reaches an extreme. In this case, the Sun appears directly over the Tropic of Capricorn in the southern hemisphere. From now until the solstice in June, days will be getting shorter in the southern hemisphere and longer in the northern hemisphere.
Mercury: Ophiuchus -> Sagittarius
This tiny planet puts on a good show for both hemispheres when it reappears mid-month in the western sky at sunset.
Venus: Sagittarius -> Capricornus
The "evening star" has put on a wonderful show for southern hemisphere observers but now Venus declines slightly in altitude. From the north, however, the opposite is true and the bright planet climbs higher in the evening sky. At the beginning of the month, the sunset sky is ablaze with two "evening stars" as Jupiter joins our nearest neighbour. The best view occurs on the first day of the month when the crescent Moon joins in, occulting Venus in the process.
Mars: Ophiuchus -> Sagittarius
The red planet is at conjunction on 5 December and thus is not observable this month.
2 Pallas: Columba -> Caelum
A small telescope will be necessary to see this eighth-magnitude small solar system body at opposition on 4 December.
Jupiter: Sagittarius
The largest planet in the solar system is very near Venus early in the month, appearing also with the Moon on 1 December. The Moon occults Jupiter on 29 Jupiter but the planet will be too close to the Sun to be seen.
Saturn: Leo
At west quadrature on 13 December, this is an excellent time to observe Saturn through a telescope as the three-dimensional effect of shadows upon the rings (nearly edge-on this month!), planetary disc and satellites is at its most pronounced. The ringed planet rises just before midnight.
Uranus: Aquarius
At east quadrature on 10 December, Uranus now sets before midnight, just as Saturn rises.
Neptune: Capricornus
A small telescope is necessary to view the most distant planet in the solar system. It appears very near Venus just after Christmas and sets mid-evening.

The Celestial Sphere

Constellations are patterns of stars in the sky. The International Astronomical Union (IAU) recognises 88 different constellations. The brightest stars as seen from the Earth are easy to spot but do you know their proper names? With a set of binoculars you can look for fainter objects such as nebulae and galaxies or some of the closest stars to the Sun.

Descriptions of the sky for observers in both the northern and southern hemispheres are available for the following times this month. Subtract one hour from your local time if summer (daylight savings) time is in effect.

Local Time	Northern Hemisphere	Southern Hemisphere
1730 hours (1830 hours summer time)	45° N	30° S
1930 hours (2030 hours summer time)	45° N	30° S
2130 hours (2230 hours summer time)	45° N	30° S
2330 hours (0030 hours summer time)	45° N	30° S
0130 hours (0230 hours summer time)	45° N	30° S
0330 hours (0430 hours summer time)	45° N	30° S
0530 hours (0630 hours summer time)	45° N	30° S

For More Information...

Consult our online glossary for non-technical explanations of many of the astronomical terms used in these pages.
Blue moons, eclipses, the dates of Easter and much more can be found at the Interactive Astronomy Pages.
For more information about the objects and events described in SkyEye, visit these astronomy-related sites.

Credits

Much of this information can be found in this month's issue of your favourite amateur astronomy magazine available in your local bookshop. Another excellent source is the current edition of the Astronomical Calendar by Guy Ottewell and published by the Universal Workshop at Furman University.

The image of the variable star V838 Monocerotis in the SkyEye banner is courtesy of NASA, ESA and the Hubble Heritage Team (STScI/AURA). Located 20,000 light years away in the constellation of Monoceros, V838 Mon temporarily brightened in early 2002. The reason for this outburst is not understood. The resulting light echo, the light from the stellar explosion illuminating the dust surrounding the the star, was captured by the Hubble Space Telescope in October of that year.