Now is a good time for evening stargazers to view four of the five naked-eye planets.
The easiest is Jupiter which dominates the southern sky in the early evening. Far outshining all stars, Jupiter is the third brightest night sky object behind only the Moon and Venus.
While Jupiter appears as a bright star to the naked eye, most binoculars can reveal its disc-like shape. And if the binoculars are held very steady, up to four of Jupiter's moons can be seen looking like tiny stars in alignment.
On any given night, however, all four may not visible since, as they orbit Jupiter, one or more might be hiding behind or in front of the huge planet. These four largest of Jupiter's many moons--Io, Europa, Ganymede, and Callisto--are called the Galilean Moons in honor of Galileo who discovered them with his new telescope in 1610. They are only slightly larger than our moon, but 1,500 times further away.
Jupiter is now up when the skies darken and doesn't set until the wee hours of morning, so you can watch it all evening. Not so with the other three.
Mars, Venus and Mercury are low in the west at dusk and set before the sky gets completely dark, so don't linger. Start looking 30 minutes after sunset. If you have binoculars, use them, and since the planets are quite low, you'll need a clear view of the western horizon.
Of the three Venus is by far the brightest and easiest to spot. Once you've found Venus, look for fainter Mercury three moonwidths to the lower left. Again, binoculars will help, especially for those (like me) with aging eyes.
Fainter Mars is 10 degrees to their upper left. (Remember, the width of your fist held at arm's length is 10 degrees.)
After you;ve found them, keep watching them nightly as this is a show that changes each evening.
For the next week or so Venus and Mercury stay in about the same position relative to each other as they gradually approach Mars. The evening of Aug. 31, a thin crescent Moon visits the planetary trio. By Sep. 4, the planets form a nearly equilateral triangle with brilliant Venus to the right, Mercury to the lower left and Mars to the upper left.
In what might be the show's climax, Venus passes less than a moonwidth from Mars Sept. 11. After that, Mercury and Mars sink into the setting Sun and Venus begins asserting herself as the "evening star" where she will remain until well into 2009.
Maybe you've noticed there's been no mention of Saturn. The ringed planet, which has been gracing our evening sky all year, is now hidden in the glare of the Sun. Sep. 3 it reaches conjunction with the Sun--astronomers' way of saying it is exactly on the other side of (behind) the Sun. By October it will have moved into the morning sky.
[bullet] Sky Calendar.
- Aug. 28 Thu. morning: The crescent Moon is three moonwidths above the Beehive cluster low in the east shortly before dawn.
- 30 Sat.: The Moon is new.
- Sept. 2 Tue. evening: The crescent Moon is below the star Spica.
- 6 Sat. evening: The nearly quarter Moon is two moonwidths below the star Antares.
- 7 Sun.: The Moon is at 1st quarter.
- 9 Tue. evening: The Moon is below Jupiter in the south.
[trailer] Stargazer appears every other week. Paul Derrick is an amateur astronomer who lives in Waco. Contact him at 918 N. 30th, Waco, 76707, (254) 753-6920 or firstname.lastname@example.org. See the Stargazer Web site at stargazerpaul.com.