You are here

Moon and Antares

August 7, 2011

The gibbous Moon flirts with danger tonight: It passes between the head and heart of Scorpius, the celestial scorpion. Three stars to the right of the Moon form the wide head, while the heart is marked by Antares, a brilliant orange star to the lower left of the Moon.

Antares is one of the giants of the galaxy: a behemoth that's about 350 times wider than the Sun. If it took the Sun's place in our own solar system, it would engulf Mercury, Venus, Earth, and Mars, and reach halfway out to Jupiter.

The star produces so much energy that, to have comfortable conditions for life, a planet would have to be more than 200 times farther out than Earth is from the Sun -- farther than any planet in the solar system.

Although it looks quite bright, most of the energy Antares produces is in the infrared. It's invisible to the human eye, but it's a form of energy that we feel as heat.

Antares produces so much infrared energy because its surface is thousands of degrees cooler than the Sun. That gives the star its characteristic orange color, but also ensures that most of its energy comes out at wavelengths that are much longer than red light -- the infrared.

Look for this big, cool star close to the Moon tonight. The Moon moves closer to Antares as the night progresses. They set around one o'clock in the morning. And if you miss them tonight, try tomorrow night, when Antares will be a little farther to the right of the Moon.


Script by Damond Benningfield, Copyright 2011


Get Premium Audio

Listen to today's episode of StarDate on the web the same day it airs in high-quality streaming audio without any extra ads or announcements. Choose a $8 one-month pass, or listen every day for a year for just $30.