Courtesy of EarthSky
A Clear Voice for Science
You’ll have to stay up fairly late to see the moon and the planet Saturn tonight – or wake up early tomorrow. Our chart shows the eastern sky at around 10 to 11 p.m. The moon rises first. Then Saturn follows the moon above the horizon a bit later. For the precise rising time of the moon and Saturn into your sky, check the links on our almanac page.
After they rise, the moon and Saturn travel westward across the sky throughout the night. They do this for the same reason that the sun moves from east to west during the day. It’s because the Earth spins from west to east on its rotational axis. Therefore the sun, moon, planets and stars appear to wheel westward across our sky throughout each day and night, but it’s really the Earth that’s doing the spinning.
Now consider the Earth and Saturn in their orbits around the sun. Day by day, the Earth – the 3rd planet from the sun – is gaining ground on Saturn, the 6th planet. Earth’s orbit is smaller, and we move faster than Saturn in orbit, so we come between Saturn and the sun nearly every year. On March 21, 2010, the Earth will pass in between the sun and Saturn – and will come closest to the ringed planet for this year. At that time, Saturn will be opposite the sun in our sky. Thus, Saturn will shine all night long on March 21-22, rising around sunset and setting around sunrise.
Between now and then, Saturn will be come into view earlier each evening. Watch for it!
Written by Bruce McClure
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