Habitable planets: Is Earth one of them?

The European Space Agency’s Venus Express, in orbit about Venus, is trying to determine whether Earth is habitable.

While this may seem like a pointless exercise, there is a serious purpose behind the effort. To the Venus Express, Earth looks like a single dot of light with no visible surface features. This mimics how other planets may appear to spacecraft, such as NASA’s Kepler Mission, as they scan outside the solar system for habitable planets.

Using visible and infrared thermal spectrometers, scientists have been able to spot both oxygen and water vapor in their scans of Earth. They also hope to find a “red edge” that indicates photosynthetic life.

“We’re not going to learn anything new about Earth,” remarked one of the investigators, “but, hopefully, we can spot clues to look for when spacecraft search for life on other worlds.”

Focus on the planets

Mercury is low in the east-southeast at dawn as the month begins but by Nov. 10 will become lost in the solar glare.

Venus, the brightest object in the evening sky other than the moon, shines brightly in the southwest at dusk. Look for Venus to become even more prominent as it closes in on its companion planet Jupiter during the course of the month.

Mars is lost in the glare of sunset throughout November.

Jupiter, second only to Venus in brightness, is high in the southwest, to the upper left of Venus, as the month begins. As always, Jupiter’s moons provide viewers with telescopes the sight of their dance around and across the face of the giant planet.

Saturn rises after midnight in the southeast very near the constellation of Leo. Saturn’s ring system is now nearly totally edge-on and affords viewers little but a thin line of light at dawn. A consolation prize is that Saturn’s moons will be more prominent until the rings again begin to open in late 2009.

Uranus in Aquarius and Neptune in Capricorn are easily spotted by telescope as blue-green and blue-gray disks respectively. A finder chart for these far-distant planets may be found at skyandtelescope.com/uranusneptune.

November events

1 Sunrise, 7:13 a.m.; sunset, 5:24 p.m. The crescent moon lies about midway between Venus and Jupiter in the southwest at dusk.

2 The first Sunday in November is when we set our clocks back one hour as we go from daylight saving time to standard time for the winter. The moon is at apogee or the farthest distance from Earth today.

3 Jupiter is just to the upper right of the moon at dusk.

6 Moon in first quarter, 11:03 p.m.

13 Full moon, 1:18 a.m. The full moon of November is called the Beaver Moon or Frost Moon. Aldebaran, the “red eye” of Taurus the Bull, is to the lower right of the moon as they rise at midevening.

14 The moon is at perigee or closest approach to Earth today.

17 The Leonid meteor shower peaks tonight but will be largely masked by the bright gibbous moon. Look for a sparse display of swift, bright fireballs that often leave a persistent trail.

19 Moon in last quarter, 4:32 p.m.

21 Saturn is situated to the left of the moon after midnight on the eastern horizon. The sun enters the astrological sign of Sagittarius but astronomically is just leaving Libra.

22 The sun enters Scorpius on the ecliptic.

27 New moon, 11:55 a.m.

29 The sun enters Ophiuchus on the ecliptic. This is not one of the traditional houses of the zodiac.

30 Jupiter and Venus have a spectacular conjunction being only two degrees apart. The crescent moon lies to the lower right. Sunrise, 6:51 a.m.; sunset, 3:57 p.m.