Jimmy Westlake: Planets gather in the May sky
Venus, Jupiter, Mars and Mercury will appear to come near each other
May 4, 2011
Steamboat Springs — During May, our predawn sky will be buzzing with activity as the planets Mercury, Venus, Mars and Jupiter huddle together and glide past each other in apparent near collisions. Most of the drama is overplayed because these planets are really tens of millions of miles apart and their close proximity in our sky is merely a line-of-sight illusion. Even so, to see several bright planets in such a tight grouping is a remarkable sight and one that you will not soon forget.
Because our solar system is flat, like a pancake, the planets, the sun and the moon closely follow a narrow path around the sky called the ecliptic. Faster-moving planets occasionally
catch up with and pass the slower-moving ones, providing us earthlings with spectacular conjunctions and apparent near misses.
Astronomers express the apparent closeness of planets in degrees. For example, your clenched fist, held at arm's length, is about 10 degrees across. The tip of your index finger, at arm's length, is about 1 degree across. On this scale, the full moon is about half a degree across. Yep, you can easily hide that big old full moon behind the tip of your index finger.
The celestial fun begins at about 5 on May mornings, when dazzling Venus first pops above the eastern horizon. Mercury follows minutes later, and the Mars-Jupiter pair appears after that. By 5:30 a.m., all four planets should be visible, provided you have a clear, unobstructed view of the eastern horizon. Venus and Jupiter will be easy to spot, but Mercury and Mars could be a little more challenging in the brightening sky. A pair of ordinary binoculars will enhance the view.
Over the next three weeks, watch for Mercury to pass just 1.5 degrees from Venus on Tuesday, Jupiter and Venus to pass within 0.5 degrees of each other on May 11, Mercury to pass 2 degrees from Mars on May 21, and Mars to pass only 1 degree from Venus on May 23.
Saturn is the only planet visible with the naked eye not participating in this planet parade. He has the evening sky all to himself and is still basking in his own spotlight after his April 3 opposition. To spot Saturn, go outside at about 9 p.m. and look about halfway up in the southeastern sky. There, you'll spot a bright yellowish "star" that doesn't twinkle like the stars around it. This is Saturn. Now is prime time to aim your telescope at Saturn and ogle his spectacular rings and moons. Any small telescope at 30-power or more should reveal the rings and the giant moon Titan.
If early morning sky-watching is not your cup of tea, relax. Venus and Jupiter will return to our evening sky this Halloween, and Mercury will make an evening appearance in mid-July. We'll have to wait until next March for Mars to enter our evening sky.
Professor Jimmy Westlake teaches astronomy and physics at Colorado Mountain College's Alpine Campus. He is an avid astronomer whose photographs and articles have been published across the world. His "Celestial News" column appears weekly in the Steamboat Today newspaper. His "Cosmic Moment" radio spots can be heard on local radio station KFMU. Also, visit Westlake's website at http://www.jwestlake.com.