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Moon and Jupiter

June 16, 2012

After passing behind the Sun a few weeks ago, the planet Jupiter is climbing into view in the dawn sky. It’s low in the east about 45 minutes before sunrise, and looks like a brilliant star. It’s especially easy to pick out tomorrow because it’s close to the upper right of the Moon.

Jupiter passes behind the Sun about every 13 months — a result of the relative motions of Jupiter and Earth.

Jupiter is so far from the Sun that it takes the giant planet about 12 years to make one full turn around the Sun.

Earth is only one-fifth as far from the Sun, so our planet has a much smaller track around the Sun. And a body in a closer orbit moves faster than one that’s farther away. Put the two together, and it means that Earth completes an orbit in just one year.

As Earth moves around to the opposite side of the Sun from Jupiter, the planet disappears for a while in the Sun’s glare. But it quickly emerges in the morning sky, as it’s doing now.

Over the next few months, Earth will loop closer to Jupiter, and will pass between the planet and the Sun in early December. When that happens, Jupiter will be in view all night, and it’ll shine brightest for the year.

Until then, watch as Jupiter climbs a little higher into the dawn sky each morning. And over the next few weeks, another brilliant planet will climb with it: Venus. It’s so low that it’s tough to see right now, but it, too, will quickly put on a better showing as we head into summer.


Script by Damond Benningfield, Copyright 2012


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