Jupiter takes main stage
The king of the planets will get your attention in the Butler southeast sky this month. It reached its closest approach to Earth last month, something astronomers call opposition, but it's still just about as close at 381 million miles from our backyards.
Believe or not, that's close for Jupiter. Because of the fact that Earth's and Jupiter's orbits are not exactly circular, Jupiter is the closest it's been to Earth since 1999. It's by far the largest planet in our solar system with an equatorial diameter of 88,000 miles, dwarfing our 8,000-mile-wide Earth. In fact, if Jupiter were a hollow sphere you could fill it with more than a thousand Earths!
No doubt you probably heard Jupiter was hit in late July by what most astronomers believe to be an asteroid about the size of a football field. An amateur astronomer in Australia was the first to report it. Fortunately for me, this news broke while I and more than one hundred other amateur astronomers were attending the Nebraska Star Party just outside Valentine, Neb.
As soon as we heard about it, and it was dark enough outside, we all had our astronomical gear aimed at Jupiter. We couldn't see the blemish near Jupiter's south pole right away because it was turned away from our view. Even though it's a huge plane, it whirls around on its axis once every 10 hours. That night, we had to wait a few hours until the side of Jupiter with the black smudge rotated our way. NASA's Hubble telescope got a much better view than our army of telescopes, but we could still faintly see the point of impact.
The smack mark on Jupiter has now faded away, but there's still much to see on and around the largest planet of our solar system.
It's very bright in our evening skies as it rises in the southeast. Nothing else is even close in brightness in the night sky, with the exception of our moon.
I think this month is prime time to Jupiter gaze. It's certainly a lot more user friendly to observe, as nightfall begins sooner and Jupiter is a little higher in the southeastern sky. It's an obvious telescope target, but I want to advise you to wait until about 9:30 or so — an hour and a half after sunset to start telescoping it. Before that, Jupiter is still pretty low in the sky and you have to look through a lot more of Earth's blurring atmosphere.
Jupiter is basically a huge ball of hydrogen and helium gas, much like our sun. The gas gets thicker and denser as you approach what's believed to be the planet's rocky core. So, when that asteroid hit Jupiter in late July, it never made landfall because there is no real land.When you get Jupiter in the eyepiece of your telescope, you'll see at least some of its horizontal parallel cloud bands on the disk of the gargantuan planet. Even the smallest of scopes with decent focus can usually pick up two of the dark cloud bands running on either side of Jupiter's equator. But since Jupiter is so close this month, you'll probably see a lot more. You might even see some faint color to the bands.I can't believe how well I'm seeing Jupiter with my big scope these nights. The clouds on Jupiter are mostly made up of ammonia and methane compounds. They swirl around Jupiter at speeds more than 200 mph and contain eddies and storms within them. The biggest of Jupiter's storms is the famous Red Spot, which is way bigger than even our Earth. Other smaller red spots also have been seen on the great planet.Jupiter's atmosphere is so active because of the planet's immense mass and its resultant huge gravitational force. That gravity literally puts the squeeze on Jupiter and compresses the giant gas ball. That compression produces a lot of internal heat that drives the energetic Jovian atmosphere. There's also a lot of lightning on Jupiter. Because of the huge magnetic field generated by it's rapid rotation, aurora are common around Jupiter's pole. There's a lot going on around the big guy of our solar system.When you're viewing Jupiter, or anything else in your telescope, another piece of advice I can give that really helps is to start with a lower magnification eyepiece and work your way up to a higher magnification. You will reach a point of limiting higher magnification where the image will really get too muddy. There's no sense in seeing a blurry Jupiter, so bump down to a lower magnification.Also, remember not all nights are the same for telescope viewing. Even if the skies are clear, high winds in the upper and lower atmosphere can diminish what you see and how much magnification you can obtain clearly. If Jupiter doesn't come in too clear one night, try it again the next night, or whenever.One other thing: It's always a good idea to look through your telescope at Jupiter or any other object for a continuous extended time. Try to keep your eye plugged to the eyepiece for at least 10 minutes at a time. That will give you more time to get used to the different light level and will allow you to see more detail.Other attractions around Jupiter are its four largest moons, which look like little stars in a line on either side of the planet, depending on where they are in their individual orbits. Even the tiniest of scopes and binoculars can pick them up. I even know some people who can spot traces of them with the naked eye.I'll have much more on Jupiter's Galilean moons in next week's Starwatch.<B><I>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.</I></B>
