Introduction
The second half of November brought more cloudy skies and snow to Utah. The temperatures also declined slightly, making stargazing a little more unpleasant. Even under these conditions, I could see Jupiter and Saturn in the evening sky, with an 80% lit Moon between the pair on the 22nd. Venus and Orion were easily visible in the early morning sky before sunrise.
Aside from colder weather and more snow, December also brings the return of two meteor showers, the Geminids and the Ursids. No planets will reach opposition this month, but three asteroids will. However, a telescope and a star chart is recommended to see them. The winter solstice will also occur this month, marking the time when the daylight hours begin to lengthen and the hours of darkness grow shorter.
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| Mercury |
Mercury should be observed in early December. This tiny planet will reach its greatest eastern elongation on the 4th, giving an observer an extra few minutes to view. A thin crescent Moon will join Mercury in the sky on the 14th. Just over a week later, on the 22nd, Mercury will reach inferior conjunction with the Sun, becoming lost from view.
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| Venus |
Venus can be found shining brightly above the eastern horizon before sunrise. The bright star, Spica, in Virgo, can be found less than 5° away at the beginning of the month. Venus will pass through Virgo by mid-month and spend the remainder of December in Libra. On the 9th, a thin crescent Moon will join Venus in the morning sky.
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| Mars |
Mars will remain too close to the Sun to be safely viewed during December.
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| Jupiter |
The gas giants will remain great targets for binoculars and telescopes. Having recently reached opposition, Jupiter will be visible during most of the night throughout December. A pair of binoculars will easily reveal the four Galilean Moons, while a telescope can show observers the Great Red Spot, cloud bands, and transits of the Galilean Moons. On the 22nd, the Earth's own Moon can be found just 5° from Jupiter. A short distance away, the Pleiades can also be found.
Saturn can be found in Aquarius, high in the southwest sky, after sunset during December. Even in cold temperatures, the ringed planet is still worth a look. The Moon will pass just 2° from Saturn on the 17th.
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| Neptune |
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| Uranus |
The two ice giants can be viewed through binoculars but will look their best through a telescope. Uranus reached opposition during November, making this planet visible nearly all night throughout December. This ice giant can be found about halfway between Jupiter and the Pleiades. A nearly Full Moon will join this planet in the sky on the 23rd when the pair will be just 3° apart.
Neptune can be found trailing Saturn in the planet trail. The most distant planet will be visible most of the night during December, but interested observers should view its blue disk before midnight to get the best views. The Moon joins Neptune in the sky on the 19th.
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Meteor Showers and Asteroids |
December will offer plenty for interested observers to view. Unfortunately, most of these events occur later in the month when most individuals are busy with holiday plans. Nevertheless, the Geminid Meteor Shower will peak on the 14th under a Moon-free sky. Observers can expect approximately 150 meteors per hour radiating from the constellation Gemini.
The second meteor shower will peak on the 22nd but may be subpar due to a 74% lit Moon in the sky. The Ursids can produce up to 10 meteors per hour, but outbursts have occurred with rates of up to 25 meteors per hour. Look towards Ursa Major to view these meteors.
Three main belt asteroids will reach opposition this month, beginning with Vesta. Each asteroid will require a pair of binoculars to view, but I highly recommend a telescope and a star chart (or phone app). Vesta can be found on the border of Orion and Gemini on the 21st, its date of opposition. Use Betelgeuse and Saiph (the star that represents the knee of Orion) to form a line towards Vesta. A star chart is helpful so that it can be compared to the field of view, so the observer knows which point of light is the asteroid.
The next asteroid to reach opposition is Metis. This occurs on the 22nd. Follow the line formed with Saiph and Betelgeuse and continue through Vesta to reach Metis. Again, a star chart will be helpful to compare this region of the sky with the field of view through a telescope. The "extra" point of light will be Metis.
The final asteroid to reach opposition this month is Astraea. This opposition will occur on the 27th. On this date, an observer can form a line through Rigel and Betelgeuse and continue towards Gemini. On the border of these two constellations, the observer will notice a point of light that does not appear on star charts. This is the asteroid Astraea. An observer can also view the region of the sky where these asteroids are located and notice them move over different nights.
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Monthly Breakdown |
December 04: Mercury reaches greatest eastern elongation
December 05: Last Quarter Moon🌗
December 09: Moon passes within 4° of Venus
December 12: New Moon 🌑
December 13: Moon passes within 4° of Mercury
December 13/14: Geminid Meteor Shower peaks 🌠
December 17: Moon passes within 2° of Saturn
December 19: Moon passes within 2° of Neptune
December 19: First Quarter Moon 🌓
December 21: Asteroid Vesta reaches opposition
December 21: Winter Solstice
December 21/22: Ursid Meteor Shower peaks 🌠
December 22: Asteroid Metis reaches opposition
December 22: Moon passes within 3° of Jupiter
December 23: Moon passes within 3° of Uranus
December 26: Full Moon 🌕
December 27: Asteroid Astraea reaches opposition
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| Now get outside and look up! |
Planet images were taken by NASA.
Andrew vs. the Cosmos image was taken by Jeff Greenland.The Milky Way and Trees image was taken by Andrew Greenland.
Orion, Taurus, and Pleiades image was taken by Andrew Greenland.
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