Stargazer Alert! Venus and Jupiter in Conjunction This December

The planets (plus Pluto) in an approximate size, but not distance, comparison

—Image courtesy NASA/Lunar and Planetary Laboratory

The astronomy gods are giving me a pretty nice birthday present this year: a planetary reunion.

On December 1 at 7:36 p.m. ET, Venus and Jupiter will be in conjunction, the astronomical term for “really close together as far as observers on Earth are concerned.”

If the skies are clear, stargazers will be able to see the planets shining just two degrees apart, with a partially lit moon sitting three degrees away from Venus.

The same two planets met up once before this year on the morning of February 1. They won’t be in conjunction again until May 2011.

Even better from a fun coincidence point of view, for the December reunion the planets will meet in the constellation Sagittarius—my astrological sign.

It’s brief and a bit blurry, but here’s an animation of what the event should look like:

Of course, being in conjunction has nothing to with the actual distance between the planets.

Although they will both be in Earth’s line of sight, Venus is about 25 million miles away in an orbit closer than Earth to the sun.
—Venus image courtesy Magellan Project, JPL, NASA

By contrast, Jupiter is 390 million miles away in the fifth most distant orbit from the sun. (Check out NG’s interactive solar system for a visual reference.)

Planetary conjunctions happen throughout the year, with different bodies meeting up in the morning or evening skies. Next Monday, for example, Mercury and Mars will have a celestial meeting just after 10 p.m. ET.

—Jupiter image courtesy NASA

The Tel Aviv University Astronomy Club keeps a nice set of online charts of planetary conjunctions spanning from A.D. 0 to 2890, in case you desperately need to know what day Mercury and Uranus will brush past each other in the year 2345 (the answer: March 21).

This year alone there will be a grand total of 22 conjunctions, so I guess my upcoming astro-gift isn’t exactly unique. [Okay, so it turns out my b-day event is kinda special after all. Stargazer Andrew Fazekas reports that the Venus-Jupiter-moon meeting will be an unusual event, especially because it’ll happen at the right time of night for most anyone to see the show. Neat!] But that won’t stop me from getting out beyond the city lights and—clouds willing—taking in the show.

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