Monday, August 09, 2010

Upcoming Astronomical events

Well, the big day for the ongoing meetup between Venus, Mars, and Saturn has been and gone. Yesterday was their closest grouping, and now, like old schoolfriends who were once close, they will begin to drift apart.

Only don't tell them that, because they've got some more shows to put on.

August 9 (tonight) -Venus closest to Saturn. Whoopsie, too late for me, but the sky was a clouded mess tonight anyway. Venus made its closest pass to Saturn, about 3 degrees.

August 10-14: The Persieds. These aren't related to the planetary assembly in the Western sky, but they are an astronomical event worth seeing. The Persied meteor shower will peak on these nights, or more precisely, these mornings. Look to the northeast after midnight. As a bonus, the Moon will have set long before the start of the show, so its glow won't drown out any dimmer meteors. If the beautiful meteor a friend spotted over Coney Island last week was a harbinger of things to come, this may be a spectacular meteor shower.

August 11-12: The Moon joins the party. On the evening of August 11, an almost invisibly thin crescent Moon will hide below Mercury, briefly showing up just after sunset for anyone keen-eyed and clear-horizoned enough to see it. On August 12 a somewhat thicker crescent will lurk below and to the right of Venus, making a straight line with it and Mars. By August 13 an even thicker crescent will be just below but now to the left of Venus - and this time it will line up with Saturn. Watch for the eerie glow of Earthshine causing the unlit portions of the Moon to become visible.

August 12 - 25: Venus and Mars continue the dance. According to the 2010 edition of Guy Ottewell's Astronomical Calendar, an 82-page coffee-table-sized softcover that is an indispensable reference guide to the night skies, Venus will be within three degrees of Mars during this entire period. They will be about two-thirds that distance apart on August 18, but will be almost as close on August 16 through the 21.

Ottewell also notes that this period will be the beginning of a Triple Conjunction* between Venus and Mars. Triple Conjunctions of Venus and Mars are not particularly rare, but they are worth noting. The first conjunction will be on August 19. At some point - I'm not sure when - Venus will appear to move backwards in its orbit (this is called "retrograde motion") and pass Mars going the other way on the evening of October 1. Venus will catch up to Mars once again on May 23, 2011.

End of August: Mars, Venus, and Spica in a 5-degree pattern. You may not know which star is Spica, but Mars and Venus will be happy to help you figure it out. Venus and Spica will pass within one degree of each other on August 31.

Jupiter rising. As all this is going on in the West, Jupiter is rising in the East, getting ready for its fantastic show next month, when it will be at its biggest and brightest in twelve years. Plus you can use it to find another planet, dim and distant Uranus. But that is weeks away, on September 22.

Notice that nowhere is there any hint of "Two Moons on August 27" - because that's not going to happen. It won't happen this year, it didn't happen last year, and it hasn't happened at all since 2003 - which was the first year it didn't happen. In fact, Mars is very tiny and dim right now. But look at all the other cool stuff there really is to see in the next few weeks!

*One of my fondest childhood memories is of the Spring of 1981, my last year before entering High School. So many things seemed to be lining up to justify and approve of the things that held my interest. Two things that literally lined up were Jupiter and Saturn, shining brightly and close together in the Southeast after sunset. They were going through a Triple Conjunction - as well as a "Great Conjunction" and a Colbertesque "Greatest Conjunction." This was a remarkable thing to see, and as far as I know, I was the only person in the world who actually bothered to observe it. If there were others, I'd love to hear from them.

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