Full moon will light Halloween night sky
The best celestial event of Halloween week 2012 will be a full moon. The exact date of the full moon is Monday night, but on Wednesday evening the moon will still be more or less full, rising a little after 7 p.m. above the eastern horizon.
By about 8 p.m. you'll notice that it has a starry companion trailing it to the lower left.
That bright tagalong is actually the planet Jupiter, the largest planet in our solar system. It's by far the brightest starlike object in the evening sky this autumn.
It's so bright because it's so large, with a diameter of 88,000 miles, more than 10 times the diameter of Earth. It's also as bright as it is because Earth and Jupiter are approaching their minimum distance from each other this year. Jupiter is less than 400 million miles away right now and by early December it will only be a little over 375 million miles from Earth.
With just a pair of binoculars you can see up to four of Jupiter's bright moons that resemble tiny little stars on either side of the planet. They orbit Jupiter in periods of 2 to 17 days. With a small telescope you might see some of Jupiter's cloud bands that stripe the big gaseous planet.
Another Halloween treat is the Pleiades star cluster, otherwise known as the Seven Little Sisters. Pleiades are also seen in the east early in the evening, visible as soon as it's dark enough.
On Tuesday evening the Seven Little Sisters will be just to the left of the moon, and on Halloween night the tight little cluster of stars will be poised just above the waning full moon.
WYou can see even with the naked eye that Pleiades resembles a tiny Big Dipper. If your vision is sharp enough you'll see six to seven individual stars in that tight group. Through binoculars or a telescope you'll see many, many more.
Astronomically the Pleiades is a group of young stars about 410 light-years away that were born together out of a huge cloud of hydrogen gas. Before that was known, many ancient cultures feared the appearance of the Pleiades as an omen of possible oncoming catastrophes.
It was thought that when the Pleiades reached its highest point in the sky, about midnight, disaster could strike. This high point of the Pleiades occurs every year around Halloween.
If you're enjoying Halloween in the country there's a really nice ghostly image in the heavens: It's the Milky Way band, the thickest part of the Milky Way Galaxy. This time of year it stretches from the northeast horizon to nearly overhead, and then on to the southwest horizon.
Our sun and all of the billions of stars that we see in our sky are all members of our Milky Way Galaxy. The spiral disk of our Milky Way Galaxy is more 100,000 light-years in diameter, but only about 10,000 light-years thick, although our galaxy's center is much fatter than that.
Back in the "old" days when people didn't know about galactic structure, the Milky Way band took on a much more spiritual meaning. Many of the ancient cultures equated it with heaven and the after life. The ancient Greeks thought it was home to the palaces of the great gods.
Mike Lynch is an astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and is author of the book, "Washington Starwatch," available at bookstores. Check his website, www.lynchandthestars.com.
The Everett Astronomical Society: www.everettastro.org/.
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