Three planets congregate to the right of the Moon this evening: Saturn, Mars, and Venus, the "evening star."

Saturn is the closest one to the Moon. It's to the upper right of the Moon, and looks like a golden star. And it's also the biggest of the three worlds. In fact, it's the second-largest planet in the solar system -- about nine times the diameter of Earth.

Saturn consists of layers of gas wrapped around a small, solid core. The layers of gas are topped by globe-encircling bands of clouds made of sulfur compounds, water, ammonia, and other chemicals.

Like the clouds here on Earth, the clouds on Saturn undergo convection -- air currents carry material in a loop from bottom to top and back down again. The convection creates static electricity. When enough electricity builds up, it discharges just as it does here on Earth: as lightning.

[SFX: Saturn lightning]

The Cassini spacecraft has heard the lightning as this crackling static in radio waves from the planet. The crackles indicate that some of the discharges can be hundreds of times stronger than lightning on Earth.

And earlier this year, Cassini saw lightning on Saturn for the first time, recording several flashes in a giant thunderstorm. The flashes were at least as strong as the most powerful lightning here on Earth -- buffeting Saturn's clouds with powerful displays of light and sound.

[SFX: Saturn lightning mixed with Earth thunder]

Script by Damond Benningfield, Copyright 2010