Wednesday, March 14, 2012

Three degrees of separation -- so close, and so far away

Three Degrees of Separation -- So Close, and So Far Away

Interesting sky last night. Looking like a pair of headlights approaching in the night sky, Jupiter (low beam) and Venus (high beam) are in conjunction. Today they reached their closest apparent proximity in the sky, separated by just 3 degrees. Of course, their apparent closeness to each other is just an illusion. Venus lies between us and the sun. It's separated from Jupiter, a giant outer planet, by hundreds of millions of miles. We're actually looking past Venus to its neighbor, deep in the outer solar system, 483 million miles from the sun (in contrast, Venus is just 36 million miles from the sun). Their relative brightness is deceptive, too. Jupiter is far larger and brighter, and when Venus isn't dominating the sky as the morning star or evening star, Jupiter is the brightest planet in the sky,
brighter than any star.

Venus is enroute to an April 1 rendezvous with the Pleiades star cluster, the fuzzy patch above and to the left of Venus. The Pleiades are called the Seven Sisters in Greek mythology. Seven is the number of stars seen clearly by someone with really good eyesight with the naked eye, but actually there are about 1,000 stars in the cluster. The approach of Venus to the Pleiades is also more apparent than actual, since the Pleiades are some 400 light years away.

Even further away is the Orion Nebula, which is the middle "star" in Orion's Sword that hangs from his belt and is not actually a star at all. It's some 1,300 light years away. The Orion Constellation (see note) dominates the winter night sky but now is dropping lower in the horizon.

I took the photo in Wingra Park, and -- unusually for me -- actually used a tripod rather than shooting handheld at an insane ISO.