Planet dominates the night sky

The planet named after the king of the gods, according to old Roman mythology, is not only visible all night long right now, but is also about as close and personal to us Earthlings as it was in 2011.

This week Jupiter is around 425 million miles away and is by far the brightest starlike object in our Butler night sky. It was actually a little closer last month, but it’s in a much better place in the sky for great evening telescoping.

No matter how much urban lighting you have to put up with you can easily see 88,000-mile-wide Jupiter in the eastern sky as evening begins and through the rest of the night as it traces an arc westward high across the southern half of the sky.

For you early morning pre-twilight risers, Jupiter is still putting on a great show in the western sky as it prepares to set around morning twilight.

Last month Jupiter reached what astronomers call opposition. It’s dubbed that because just like a full moon, Jupiter and the sun are at opposite ends of the sky. This happens because Earth lies between the sun and Jupiter.

Since they’re at opposite ends of our celestial dome, as soon as the sun sets in the west, Jupiter rises in the east, and vice versa.

The Jovian giant is prowling across the sky all night long for our perusal.

You can also see that geometrically Jupiter and the Earth are at their minimum distance from each other. Earth and Jupiter get into the opposition position every 399 days, or a little over 13 months.

That’s because it takes Earth slightly longer than 365 days to make one complete orbit of the sun, while it takes Jupiter 12 years to make its much larger solar circuit.

So in the year’s time that Earth takes to circle the sun Jupiter has only made it a twelfth of the way around our home star. Because of that it takes the Earth about another month to catch up to where it’s once again in line between the sun and the king of the planets.

If you have super eagle eyes there are times when Jupiter looks like it has tiny little appendages on both sides of it. These are Jupiter’s moons.

There’s no way you can visually resolve them with your naked eye, no matter how good your eyesight is, but even a small pair of binoculars will reveal up to four of Jupiter’s brightest moons that look like tiny little stars.

I’ll have much more on the moons of Jupiter and keeping up with them in next week’s Skywatch column.

With a small telescope not only can you easily see Jupiter’s moons, but you can also clearly resolve the disk of the planet and maybe some of its cloud bands and zones that stripe the big guy of the solar system.

Jupiter is mostly just a big ball of hydrogen and helium gas, but in its outer atmosphere there’s methane, ammonia, sulfur, and other gases that create the multi-color cloud bands. There are two darker bands of clouds on both sides of Jupiter’s equator that are the easiest to spot.

There are also storms circulating in Jupiter’s upper atmosphere, with the biggest one known as the so-called Great Red Spot that’s three times the diameter of our Earth.

This giant hurricane-like storm has been raging on Jupiter for hundreds of years. Despite its moniker, the Great Red spot isn’t all that red, but much more like a pale pink.

Unless you have a moderate to large telescope and super clear conditions it’s hard to spot it in Jupiter’s southern horizon.

What also makes it tough to see is that it’s not always facing Earth. That’s because Jupiter rapidly rotates on its axis once every 10 hours, so half of the time the Red Spot is facing away from us.

Seeing that pale pink storm is definitely a stargazing challenge. There’s a great app for this. A really handy website I like to use to keep up with the Red Spot’s visibility is http://www.skyandtelescope.com/observing/objects/javascript/3304091.html from Sky and Telescope Magazine. You have to register on the site, but there’s no cost and it’s a really cool site for other great stargazing stuff as well.

In general, viewing Jupiter through a telescope requires patience.

First, off, wait until Jupiter is at least 30 degrees above the horizon so you don’t have to look through as much of Earth’s blurring atmosphere to see it. This week it should be high enough for decent viewing after 7 p.m.

Also, it’s a good practice whenever you have your telescope trained on any of the planets to take long continual views through the eyepiece.

That will not only give your eyes a chance to get used to the light level within the eyepiece, but you’ll also have a better chance of catching clearer views of Jupiter through the ever changing clarity of Earth’s atmosphere.

Get used to seeing the king of the planets in our night sky, as it will be visible in the evening well into the summer.

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