But Giant Jupiter is on the rise

It's time once again this year for the Persied meteor show over Butler.

Most years, it's a marquee stargazing event, but not this year. You can blame it on the moon, which will be washing out most of the "shooting stars" of the Persieds.

The Persieds will peak Wednesday morning in the pre-twilight sky, but also in the heavens that morning will be a waning full moon that will make the skies kind of milky, even in the countryside.

Now, for sure you'll still see some meteors, but many of them will be lost in the moonlight bath. In years when the moon isn't a factor you might see more than 50 meteors an hour. This year, you might see only about half as many.

Meteor showers occur when the Earth in its orbit around the sun runs into a trail of small debris left behind by a comet, which are basically dirty snowballs of ice with embedded debris that have highly elongated orbits that take them from the way out regions of our solar systems to the inner neighborhood near the sun. As they swing close to our home star, the dirty snowball at least partially melts, liberating and littering small bits of debris, usually ranging from the dust grains to pebble sized.

As the Earth swings into these debris trails, the debris gets sucked into Earth's atmosphere because of gravity and burnup. The meteors are slamming into our atmosphere with speed as high as 44 miles per second. Most of the light streaks we see as meteors are the not so much because of incineration but rather the temporarily atomic destabilizing of the column of air they're coming through.

Even though the Persieds show will be "moonwashed" out a bit this time around, it's still a lot of fun to lay back on a reclining lawn chair, roll your eyes all around the sky and see how many meteors you can spot. Again, the best time to watch for them will be Wednesday morning from about 2 a.m. to the start of early morning twilight. You'll probably catch a few falling stars Monday and Tuesday mornings as well.

While the Persieds won't be the pleasure they usually are, you will be impressed with the very bright planet Jupiter on the rise in the early evening southeastern sky. You can't miss it. Jupiter is in what astronomers call opposition because it's on the opposite side of the sky from the sun. That's great for watching the largest planet in our solar system because it's out all night and because of the orbital geometry of the Earth and Jupiter, making the two planets a minimum distance from each other. (See the diagram) This occurs a little more than once a year.

Because of the fact that the orbits of the planets in our solar system aren't exactly circular, some opposition distances between Jupiter and Earth are closer than others. It turns out this week Jupiter and the Earth will be separated by just a little more than 379 million miles. Now while that's not exactly a weekend trip away, that's relatively close as far Jupiter goes. In fact, Jupiter will be as close as it's been to Earth since 1999. That's why it'll be so super bright in our night sky the rest of the summer and early into the fall.

Galileo had a lot of fun and made huge history pointing his telescope for the first time at Jupiter 400 years ago, and you can have a great time with your scope as well, even a smaller scope. You can really see the disk of the planet, its horizontal cloud bands and up to four of its larger moons.

This month, though, in the early evening, you'll be disappointed with what to see. Jupiter will be fuzzy, and that's not because of your scope but because of Earth's atmosphere. Whenever Jupiter or any other rising celestial object is low in the sky, its light has to plow through a lot more of our blurring atmosphere than it does when it's higher in the sky. You can either wait to really late at night this month or wait until early September when it'll be a little higher in the sky at the start of evening. I'll have a lot more on telescoping Jupiter and its moons in coming Skywatch columns.

By the way, speaking of bright planets, there's an Internet rumor about Mars being as close to the Earth as it's been in 50 million years on Aug. 27. You might have read how Mars will be as be as big as a full moon. This just isn't true! Mars was actually as close as it has been to Earth in 50 million years on Aug. 27, 2001, but no way was it as big as a full moon. So this rumor is based on old and highly exaggerated information. You can't believe everything to read, especially on the net!

Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and is author of the book, "Pennsylvania Starwatch," available at bookstores and at his Web site www.lynchandthestars.com.

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Jupiter is very close to Earth this month, making it especially bright.