Moon and Planets

The Moon lines up between two bright planets tomorrow morning. And it practically runs over another planet, which is too faint to see with the eye alone.

At first light, Venus stands to the lower left of the Moon. It’s the “morning star,” so you can’t miss it. Mars is about the same distance to the upper right of the Moon. The orange planet isn’t nearly as bright as Venus, but it’s still an easy target.

The third planet is Uranus. It’s to the lower left of the Moon, and is visible through binoculars. Uranus and the Moon will appear closer together from the western United States than from the east. And from some other parts of the world, the Moon will pass in front of Uranus, blocking it from view.

Such an event is called an occultation. Another occultation, more than four decades ago, led to the discovery of the planet’s rings. In that case, though, Uranus occulted a star. Astronomers noticed that the star’s light flickered several times shortly before and after the star disappeared from view. That meant its light was being partially blocked — by rings.

Since then, the number of known rings has climbed to 13. All of them are faint, and most of them are thin — no more than a few miles across. Most are made of solid chunks of rock up to a few dozen feet across. At least one, though, appears to be made of ice. Today, astronomers continue to study the rings — with the help of more occultations.
 

Script by Damond Benningfield

Today's program was made possible by Mercer Caverns, in Calaveras County in California's historic Gold Country.