Jupiter, full moon to light up night as planet 'king' makes closest approach to Earth


By MIKE LYNCH
Special to the Daily News

Sunday, July 13, 2008

For the rest of this summer and into autumn, Jupiter will be the dominating bright light of the night sky — unless the moon is out, of course.

You may have already seen the king of the planets rising in the southeast as twilight ends. It's visible all night as it arcs across the low southern sky.

Jupiter is in what astronomers call opposition with Earth. They will be at their closest approach to each other, less than 400 million miles apart.

They're on the same side of the sun in their respective orbits, with the Earth lying in the 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 week, Jupiter rises at sunset and sets at sunrise.

Unfortunately, Jupiter is taking a low arc across the southern sky this summer. Even at its highest point, around midnight this month, it will only be a little over 20 degrees above the southern horizon. The lower any celestial object is, the more visual interference you have with Earth's atmosphere, especially if there's a lot of high-altitude wind.

It's still well worth checking out the great planet through a telescope or even a decent pair of binoculars. Your best viewing will be around midnight when the planet is at its highest, but even before that you'll be able to see it.

Depending on what night you look, you also may see up to four of Jupiter's biggest moons, looking like little "stars" on either side of Jupiter. These are called the Galilean moons in honor of Galileo, who was the first known person to study their orbits.

He used these moons as part of his evidence that it was the Earth moving around the sun and not the other way around.

Later on this month, I will give details on Jupiter's moons and how to watch their shadows transit the face of Jupiter.

In the meantime, this Web site from the University of Maryland will help you keep up with Jupiter's moons: http://www.astro.umd.edu/...piter.html

Jupiter is more than 88,000 miles in diameter. You can fit more than 1,000 Earths inside of Jupiter. It's 21/2 times more massive than all the other planets in the solar system combined, and has more than 21/2 times the gravitational force of Earth.

Even if you were tough enough to take a stroll on Jupiter, you still couldn't. You'd sink because Jupiter doesn't really have a surface. It's basically a big ball of hydrogen with some helium, spinning on its axis at an amazing rate of one rotation every 10 hours.

When you check out Jupiter itself through a telescope, look for two dark bands or lines running on either side of its equator. When Jupiter is rising, they will be orientated diagonally. If your scope is large enough and atmospheric conditions are just right, you may even see more cloud bands on Jupiter.

In close-up pictures of the planet you can see much more detail in its atmosphere, which is made up of cloud bands of methane, ammonia, sulfur and other elements. These clouds are whipped by winds of more than 200 mph, and within the clouds are big storm systems, including the Great Red Spot that's large enough to contain three Earths.

There are two other smaller red spots or storms whirling on Jupiter. There's also lightning that is thousands of times more powerful than that on Earth.

Jupiter's atmosphere is so active because of the heat generated within it. The giant gas ball continues to gravitationally collapse, causing it to ooze infrared radiation.

There will be a lovely conjunction of the full moon and Jupiter Wednesday, which also is the 39th anniversary of the launch of Apollo 11, the first lunar landing mission. The moon will be just to the lower right of Jupiter.

On Thursday night, the moon will be just to Jupiter's lower left. It will really light up your evenings this week!

Mike Lynch, an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis, is author of 'Florida Starwatch,' available at stores and at lynchandthestars.com.

We had a very cloudy, stormy night so no Jupiter for us.

A few facts about Jupiter:

http://en.wikipedia.org/wiki/Jupiter