Largest planet puts on show

The king of the planets will get your attention in the eastern sky this month and will continue to dominate our Butler night sky well into spring.

It reaches its closest approach to Earth this weekend, something astronomers call opposition.

Right now, the largest planet of our solar system is about 391 million miles away, the closest it’ll be to our world this year.

Believe it or not, that’s close for Jupiter. 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 about 1,200 Earths!

You can’t help but notice that while Jupiter is the brightest shiner in night sky it’s shining against the backgrounds of the brightest stars and constellations we see all year long.

The winter constellations are the best in my book centered around my favorite constellation, Orion the Hunter.

I lovingly call this part of the sky “Orion and his gang.” Specifically, Jupiter’s residing in the constellation Gemini the Twins, parked just to the right of Gemini’s brightest stars, Castor and Pollux.

Jupiter’s available in our heavens all night long as it take a very high arc.

Jupiter and Earth now are on the same side of the sun in their respective orbits around our home star, with the Earth lying in line between the sun and Jupiter.

Because of that, Jupiter and the sun are at opposite ends of the sky. That’s where the term opposition comes from. Just like a full moon, which we will have later this month, Jupiter rises at sunset and sets at sunrise. Jupiter is basically a huge ball of hydrogen and helium gas, much like our sun, only a whole lot smaller.

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 because Jupiter is so close, you’ll probably see a lot more. You may 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 at speeds up about 400 mph and contain eddies and storms. The biggest of Jupiter’s storms is the famous Red Spot that’s way bigger than even our Earth. Other smaller red spots have also been seen.

Jupiter’s atmosphere is so active because of Jupiter’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 lots of lightning on Jupiter. Because of the huge magnetic field generated by it’s its 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, just remember the general rule of thumb, higher is better.

The higher in the heavens Jupiter is, the better chance you’ll have to get a really clear look at it because your scope doesn’t have to pierce as much of Earth’s blurring atmosphere as when Jupiter’s just above the horizon.

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.

Remember, also, that not all nights are the same for viewing. Even if the skies are clear, high winds in the atmosphere can diminish what you see.

If Jupiter isn’t 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 object for a continuous extended time.

Try to keep your eye plugged to the eyepiece for at least 10 minutes. That will give you more time to get used to the different light level and will allow you to see more detail.

Another attraction around Jupiter are its four largest moons that look like little stars in a line on either side of the planet, depending on where they are in their 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.

Jupiter is so close and bright right now that if you look very carefully at it, you might see a tiny little tail.

I never really noticed this until I pointed out Jupiter to a friend of mine and he asked, “Hey what’s that little tail all about?”

That tail is actually Jupiter’s moons. I’ll have much more on Jupiter’s Galilean moons next month in Starwatch.

Mike Lynch, an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis, is author of the book, “Stars, a Month by Month Tour of the Constellations” published by Adventure Publications and available at bookstores and at www.adventurepublications.net.