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On Dec. 2, the planet Jupiter is in opposition. The sun and Jupiter will be on opposite sides of the Earth. So, when the sun sets in the west in early December, Jupiter will be exactly opposite, rising in the east.
A planet like Jupiter is at its brightest during opposition. In December the great planet shines at minus 2.8 magnitude, several times brighter than even the brightest star.
At 6 p.m. on Dec. 2, the night of opposition, you should be able to catch Jupiter in the twilight, extremely low in the east. It’s by far the brightest dot in the December evening sky. By 7 p.m. Jupiter will be about 15 degrees up the eastern horizon, or a little more than the width of your palm at arm’s length. In early December, Jupiter passes exactly overhead at 12:20 a.m. Jupiter sets in the west at 7 a.m. in early December, as the sun rises in the east.
While Jupiter peaks early in the month, it remains spectacular for all of December. By mid-month, Jupiter will be about 15 degrees above the eastern horizon at 6 p.m., when it gets dark enough to see it. It will cross the top of the sky around 11:30 p.m. and will set by 6 a.m., as dawn is just beginning. By the end of December, Jupiter will be about a third of the way up in the east at dusk, cross the top of the sky at little after 10 p.m., and set at 4:45 a.m.
Look for the near-full moon less than two degrees from Jupiter on Christmas.
While Jupiter is up all night in December, the planets Venus, Saturn and Mercury are strictly a morning affair. If you look east before dawn on Dec. 1, the three planets will be strung out across 15 degrees (a little more than your palm held at arm’s length) of sky. Looking east at 5:45 a.m., Venus will be your landmark, in between the two other planets. Venus shines at minus 4 magnitude, several times brighter than Jupiter.
Five degrees above Venus in the eastern predawn sky, look for Saturn, shining brightly at 0.6 magnitude. Then look for Mercury hanging about 7 degrees below Venus. Mercury, at minus 0.28 magnitude, is brighter than Saturn above it. This line of planets should be an easy sight at 5:45 a.m. in early December, if you have clear skies in the east, but you have to look fast; day starts to break around 6 a.m.
You can keep looking for this gathering at 5:45 a.m. for the first half of December. As the days go by, Saturn will appear higher and higher in the sky, and Venus and Mercury will appear lower and lower. By Dec. 11, still at 5:45 a.m., Mercury will be hugging the east horizon. Venus will be above Mercury and Saturn will be above them both. If you go out looking for these planets before dawn on Dec. 11, you’ll have an added bonus: There will be the tiny sliver of a crescent moon between Venus and Mercury.
In the second half of December, it will get harder to see Mercury, but Venus and Saturn will remain prominent in the early hours. At 6:30 a.m. on Dec. 31, Venus will be 10 degrees (one palm) above the eastern horizon, and Saturn will be halfway up the sky.
It seems like Mars has been hovering in the dusk sky for just about forever, and the red planet continues to hang on in December. Throughout the month, Mars hovers about 10 degrees above the western horizon as it gets dark, and sets just before 8 p.m. The planet shines at 1.2 magnitude all month. Look for the young crescent moon just to the right of Mars on Dec. 14.
Geminid shower
The peak night for the Geminid meteor shower is the night of Dec. 13-14. The active period for the Geminids is Dec. 6-19, so you may see more shooting stars than usual during that window of time. During the peak night, Geminid can produce 80 meteors an hour.
This meteor shower is a rarity in that it is caused by debris from an asteroid (3200 Phaethon) rather than by comet debris, which causes most other meteor showers. As the earth encounters debris from this asteroid at the same time every year, little bits of asteroid hit the atmosphere and burn up from friction, causing the shooting stars. Meteor showers like this are always better after midnight, when your part of Earth is facing into the cloud of comet or asteroid debris.
The Geminids are one of the most consistent, reliable showers. This should be an excellent shower, with no interference from the moon. In terms of viewing, all you need is a good, dark location, especially with a good view of the eastern sky. The constellation of Gemini is about halfway up in the eastern sky at midnight on Dec. 13. The streaks of light seem to come from this constellation, which is why it’s called the "Geminid" shower. However, keep one eye on the entire sky, since shooting stars can appear anywhere in the sky.
Other highlights
» Winter solstice: Winter starts for the northern hemisphere at 1:12 a.m. on Dec. 21 in Hawaii. This is the shortest day of the year.
» Planetarium: The Watumull Planetarium at Bishop Museum reopens on Dec. 15, after a three-month renovation. Visit www.bishopmuseum.org for more on our new hybrid system.
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Mike Shanahan is director of Education, Exhibits and Planetarium. For more information, go to www.bishopmuseum.org/planetarium/planetarium.html
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