Around the world tonight, two shining points of light can be found near the waxing gibbous moon.

They're the planet Saturn and a star - called Regulus - the brightest star in the constellation Leo the Lion. You can tell which object is Saturn and which is Regulus, because Regulus is the closer body to the moon on Monday night.



moon
©Bruce Tuten
The eclipsing moon, Saturn (left) and Regulus (top) on February 20, 2008.

Regulus and Saturn will appear to journey westward across your sky throughout the night tonight. The moon, star and planet will set below your western horizon several hours after midnight Tuesday morning. The westward motions in our sky of the moon, Regulus and Saturn are like the sun's westward motion during the day. Objects in the sky move toward the west because Earth spins continually to the east on its axis.

Every day all heavenly bodies rise in the east and set in the west because of this spin of the Earth. If you were to watch the moon over these next few nights, though, you could detect the moon's own motion in space. You'd notice, for example, that the moon rises later each day. And you'd see the moon's position - relative to the star Regulus and the planet Saturn - shift from one night to the next.

That's because the moon's true motion in space carries the moon in the same direction Earth's is spinning - continually to the east.