Loud Jupiter

StarDate: July 2, 2009

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Jupiter is one of the brightest objects in the sky -- only the Sun, Moon, and Venus regularly outshine it. But if we could see radio waves instead of visible light, Jupiter would move up the list -- and at times, it would even climb to the top. [audio: Jupiter radio 1]

Jupiter's radio waves are coming through more clearly this year because the Sun is a lot quieter than normal.

The Sun is going through the part of its 11-year magnetic cycle where it produces the fewest sunspots and outbursts of energy. This time around is especially calm, so the Sun is generating less radio energy than usual.

The Sun's quietness lets Jupiter shine through even louder.

Jupiter produces radio waves as its powerful magnetic field funnels charged particles toward its magnetic poles.

Sometimes, Jupiter's radio signal gets amped up by Io, one of its moons. Giant volcanoes on Io blast hot gas into space, forming a fat doughnut around Jupiter. As Io moves through this cloud, it creates waves that transmit power to Jupiter's poles. That charges up Jupiter's radio waves -- sometimes triggering electrical "storms" like this one recorded in April by Thomas Ashcraft. [audio: Jupiter radio 2]

Jupiter rises before midnight, and stands well up in the south at first light. It looks like a bright cream-colored star. And through ham radio receivers, it may sound like the static from a lightning storm here on Earth -- static from 400 million miles away.

Script by Damond Benningfield, Copyright 2009

For more skywatching tips, astronomy news, and much more, read StarDate magazine.

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