Mercury, the closest planet to the sun, is a shy planet. Most of the time it hides from our view because it is so close to the sun, orbiting around our home star every 88 days at an average distance of only 36 million miles away.

Our Earth circles the sun at a distance of 93 million miles. Because Mercury has such a tight orbit, it never gets too far away from our sun in the sky. When it is visible, you can see it in either the early morning or evening twilight.

For about the next week or so, Mercury will be seen easily with the naked eye in the west northwestern sky. Don't wait too late in the evening to start looking for Mercury or you'll miss it.

This week Mercury is in what astronomers call its "greatest eastern elongation" from the sun. In plain English, that means Mercury is at its farthest angular distance east of the sun in our sky.

Mercury will be 22 degrees east of the sun, so when the sun sets this week, Mercury will be trailing 22 degrees behind it. That's not all that far away from the sun, meaning that Mercury will set only about an hour after sunset, so start looking for Mercury as soon as you can toward the end of evening twilight.

After this week, Mercury will start becoming more elusive again as it moves westward among the stars, setting closer and closer to sunset, eventually getting lost in the early twilight glare.

So, to find Mercury, look in the low west-northwest sky toward the end of twilight for two moderately bright stars, one on the left and one on the right, separated by about 25 degrees, or the equivalent of two-and-a-half widths of your fist held at arm's length. The one on the left is Betelgeuse, the second brightest star in the constellation Orion the Hunter, which is now mostly below the horizon.

The "star" on the right is actually the planet Mercury, sporting a reddish hue, mainly because it's closing in on the horizon. Just like the sun and moon, the stars and planets turn reddish as they set because of Earth's atmosphere. The light from any celestial object close to the horizon has to pierce through more of the surrounding shell of Earth's atmosphere, which scatters away all but the red and orange components of the light from whatever is setting or rising.

Don't get all excited about checking out Mercury through your telescope, because, unfortunately, there really isn't all that much to see. Because the planet is so low in the sky it will be fuzzy, and even if we had a clear view you still wouldn't see much. It's over 82 million miles away and only a little more than 3,000 miles in diameter, not much larger than the Earth's moon.

Speaking of that, Mercury resembles our moon with its heavily cratered surface. The Messenger spacecraft launched in 2004 got a great look at Mercury when it passed within 150 miles of the surface this past January, and Messenger will pass by the surface twice more before it settles into orbit around the sun-baked planet in 2011. Mercury's surface temperature reaches more than 800 degrees Fahrenheit — hot enough to melt lead!

Two other planets, Saturn and Mars, are also available in the evening sky this week and they're a lot higher in the western sky than Mercury. Saturn is the brighter of two, shining high in the southwestern sky in the constellation Leo the Lion, which actually resembles a backwards question mark. As you can see in the diagram, the waxing gibbous moon passes close by Saturn Sunday and Monday night.

Saturn is definitely worth a look through your telescope with its wonderful ring system and family of moons. Saturn is just under 850 million miles away from Earth this week.

Mars is shining with a reddish glow a little lower in the western sky, about three fist widths at arm's length to the lower right of Saturn.

Later this month the red planet will cross in front of a big and bright star cluster called the Beehive cluster. It's something you definitely will want to aim your telescope or binoculars at. I'll have more on the Mars invasion of the great Beehive in next week's Starwatch column.

Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and is author of the book, "Pennsylvania Starwatch," available at bookstores and at his Web site www.lynchandthestars.com