Jupiter at Opposition
Everything about Jupiter is big. It's the largest planet in the solar system -- roomy enough to hold more than 1400 Earths. It's also the most massive planet -- heavier than all the others combined. And even its name is big: Jupiter is the Roman name for Zeus, the king of the gods of Olympus.
And right now, Jupiter's putting in a big appearance. It's visible from dusk 'til dawn, and it's brightest for the year -- brighter than anything else in the night sky except the Moon.
This king-size appearance is a result of the planet's position. It lines up opposite the Sun this week, so it's closest to Earth for the year, and it reflects the most sunlight back in our direction.
Jupiter and the other planets don't produce any light of their own. Instead, they shine by reflecting sunlight. How much sunlight a planet reflects is called its albedo. Jupiter has an albedo of around 50, which means it reflects about 50 percent of the sunlight that strikes it. That's because it's blanketed by bright clouds. By comparison, the most reflective planet is Venus, with an albedo of about 65, while the least reflective is Mercury, at about 10.
Look for Jupiter reflecting sunlight low in the southeast at nightfall. It looks like a brilliant cream-colored star -- much brighter than any of the true stars. It scuttles low across the south during the night, and is in the southwest at dawn. Jupiter will continue to put on a good show all summer long.
Script by Damond Benningfield, Copyright 2008
For more skywatching tips, astronomy news, and much more, read StarDate magazine.
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