* Astronomy

Blobrana · L

RE: December 2011

Blobrana · L

The winter solstice will arrive at exactly 12:30 a.m. Dec. 22. This marks the longest night of the year for us in the Northern Hemisphere as the sun reaches its lowest point in our sky. There are several interesting highlights in December if you can brave the cold weather.
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Blobrana · L

Two meteor showers occur this month. The Geminids peak on Dec. 14-15, but a large waning gibbous moon will wash out a good number of them. The Geminids are one of only two meteor showers caused by an asteroid rather than a comet.
On Dec. 22, the Ursids meteor shower is the debris trail of Comet 8P Tuttle. While the Ursids are not the most spectacular of displays, the moon will pose no problem this night for spotting "shooting stars."
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Blobrana · L

The last total lunar eclipse until 2014 occurs on Saturday, Dec. 10. While Arizona observers can see the beginning, the moon sets here in mid-eclipse.
The partial eclipse begins at 5:45 a.m. but you probably won't notice much for 10 or 15 minutes. By 6 a.m., though, you'll see Earth's dark shadow creeping across the face of the moon, which will hang low in the west-northwest.
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Blobrana · L

Asteroid (80) Sappho is at Opposition on the 3rd December

Asteroid (82) Alkmene is at Opposition on the 5th December

Asteroid (12) Victoria is at Opposition on the 6th December

Asteroid (198) Ampella is at Opposition on the 13th December

Asteroid (57) Mnemosyne is at Opposition on the 19th December

Asteroid (26) Proserpina is at Opposition on the 20th December

Asteroid (409) Aspasia is at Opposition on the 22nd December

Asteroid (109) Felicitas is at Opposition on the 23rd December

Asteroid (678) Fredegundis is at Opposition on the 23rd December

Asteroid (22) Kalliope is at Opposition on the 24th December

Asteroid (103) Hera is at Opposition on the 25th December

Blobrana · L

Mercury: at magnitude 2.5, starts the month in the constellation of Scorpius. Mercury makes its closest approach to the Earth (0.678 AU) at 3.40 UT , 2nd December. Mercury is at inferior conjunction (1.3° separated from center of Sun), at 8.55 UT , 4th December. Mercury is at Perihelion at 6:05 UT, 5th December. Mercury is at Dichotomy/Half phase at 18.40 UT, 18th December. Mercury is at its Greatest Elongation (21.8° West: -0.3 mag) at 3.05 UT, 23rd December.
(On December 8th, RA=16h21m05s Dec=-19°09.6' (J2000) Distance=0.705AU Elongation= 9° Phase k=7% Diameter=9.5")

Venus: is at magnitude -3.9. The planet is in constellation Sagittarius at the start of the month. It is best seen from 11.0h -16.9h. The Moon is close to Venus at 16.20 UT, 27th December.
(On December 1st, RA=18h26m13s Dec=-24°44.8' (J2000) Distance=1.448AU Elongation= 27° Phase k=89% Diameter=11.5")

Earth: A Partial lunar eclipse occurs at 12:45:24 UT, 10th December

The Moon: First Quarter Moon (declination: -2.98°) at 9:52.2 UT, 2nd December. Full Moon (diameter: 30.017', declination: 21.68°) at 14:36.4 UT, 10th December. Lunar apogee (distance to moon center: 405445.3 km, apparent diameter: 29'56.7") at 1:06.2 UT, 6th December. Last Quarter Moon (declination: -3.05°) at 0:47.7 UT, 18th December. Lunar perigee (distance moon center to earth center: 364778.5 km, apparent diameter: 33'20.6") at 2:50.7 UT, 22nd December.
New Moon (diameter: 32.349', declination: -21.76°) at 18:06.4 UT, 24th December.

Mars: at magnitude 0.7 starts the month in the constellation Leo.
(On December 1st, RA=10h46m21s Dec=+10°09.4' (J2000) Distance=1.322AU Elongation= 89° Phase k=89% Diameter=7.1")

Jupiter: is in the constellation Aries. At magnitude -2.8, the planet is best seen from 16.5h - 6.9h. The Moon is close to Jupiter (4.41°) at 16:10 UT, 6th December. Jupiter is stationary at 22:16 UT, 25th December.
Transit times of the Great Red Spot are posted in a seprate thread.
(On December 1st, RA= 1h58m23s Dec=+10°36.6' (J2000) Distance=4.145AU Elongation=143° Diameter=47.5")

Saturn: at magnitude 0.7 sits in the constellation Virgo. The planet is best seen from 4.0h - 8.0h. Saturn is close to the star Spica (4.3deg) on the 14th.
(On December 1st, RA=13h38m12s Dec= -7°43.4' (J2000) Distance=10.382AU Elongation= 43° Diameter=15.9")

Uranus: is in the constellation Pisces. Uranus at magnitude 5.8, has a bluish-green hue and appears 3.6 arcseconds wide. Uranus is stationary on the 10th December.
(On December 1st, RA= 0h03m02s Dec= -0°28.9' (J2000) Distance=19.684AU Elongation=112° Diameter=3.6")

Neptune: is at magnitude 7.9 in the constellation Aquarius. The planet is best seen from 17.5h -18.0h. Neptune is Stationary on the 9th November.
(On December 1st, RA=22h01m53s Dec=-12°38.9' (J2000) Distance=30.174AU Elongation= 79° Diameter=2.2")

Pluto: is in the constellation Sagittarius (mag 14.1). Normally, a finder chart is necessary to help in identifying the 0.1" diameter dwarf planet. The dwarf planet is best seen from 18.2h - 5.5h.
(On December 1st, RA=18h25m43s Dec=-19°19.3' (J2000) Distance=33.004AU Elongation= 28° Diameter=0.1")

The Sun enters the zodiac sign of Capricorn at 5:30 UT on the 22nd December.

Blobrana · L

Highlights:
Winter Solstice on December 22nd. This is officially the longest night of 2010, (even though the year's earliest sunset occurs two weeks earlier).
The Geminid meteors on the night of the 13th-14th. Watch out for this reliable shower.

Capricornus, the Sea Goat: Sign of the Zodiac for birth dates between 22 December and 19 January; it is the leading constellation of the "wet" or "water" constellations. Capricornus has a symmetrical shape resembling a bikini bottom, but the stars of Capricornus are very faint with no star brighter than the third magnitude. Capricornus appears low in the southern sky (never at higher altitudes). The Tropic of Capricorn (23.5 degrees South latitude) is named after Capricornus; on 22 December (on average), the Sun is directly overhead (at the zenith) at Noon along the Tropic of Capricorn. In Mythology, the Greeks identified Capricornus with Pan, the god of nature, who was pictured as half-man, half-goat. In fear, Pan escaped the giant Typhon by leaping into the Nile River and changing his tail to that of a fish. This is the origin of the word, "panic."

Meteor Showers

There are many meteor showers this month...
The Geminid Meteors Shower Peaks on the night of the 13th-14th.
The Coma Berenicids are a poorly-known minor shower, and badly need more observing. Very swift meteors, (65km/sec). Their Radiant is at RA 11h40m Dec +25°.
Ursids Meteor Shower Peaks on the 17th. A minor shower. The peak is predicted about 2200 UT. The radiant (RA 14h28m Dec +76°) is circumpolar (It never sets in northern locations). The meteors are generally slow (33km/sec) and rates are lower than the Geminids, but certainly above the background sporadic count.
The Ursids are linked with Comet 8P/Tuttle (period around 13.5 years; last at perihelion in 1994). Their peak rates can be quite variable
Also, watch out for sporadic meteors. Their rates for the Northern Hemisphere are now reaching a plateau. Expect around 12 random meteors per hour during the morning hours

Shower	Activity Period	Maximum	Radiant		Velocity	ZHR
		Date	R.A.	Dec.	km/s
Cygnids		Dec 2	13.9h	-12.0°	19.4	82.9
Taurids	Oct 30 -Nov	November	3.1h	-17.5d	25	16
Geminids	Dec	Dec 13	7.6	32.3°	34.7	25.7
Ursids	Dec 22	Dec 17	14.3	77.7°	33.4	10.3