By Peter Becker
The night sky is full of wonder any time you look, but much of the action concerning our Solar System neighbors takes place in the western area after sunset or the eastern area before sunrise. If skies are clear, a brilliant crescent Venus awaits you tonight and a nice comet named Lovejoy in the morning.
Venus, the second planet from the Sun, has been dominating the southwestern sky after sunset for several months. Shining like a very bright star, it is not easy to miss Venus. This week Venus is particularly bright, and if you have a small telescope, by all means take a look.
Venus reaches greatest brilliance around Dec. 6, at a stunning magnitude - 4.9 (the brightest night time star, Sirius, is magnitude -1.6).
Later this month, even binoculars, if propped up or held very steady, should be able to reveal that Venus is shaped as a crescent. You are more familiar with the crescent Moon; on Saturday, Dec. 7, the Moon is a rather full crescent to the upper left of Venus. If you noticed earlier in the week, the crescent Moon was much slimmer and lower, as it glided past Venus in its orbit.
The Moon and Venus both appear as crescents for the same reasons. They are spherical bodies, positioned at an angle as seen from Earth where sunlight reflects only around the Sun-facing edge.
The Moon's phase will grow towards First Quarter on Dec. 9 and Full on Dec. 17, as more and more of its lovely cratered face gets the full strength of the Sun.
Venus, however, is sliding in its orbit towards "inferior conjunction" when it is practically between Earth and the Sun, its darkened back side facing towards us. That occurs on January 11. After that date, Venus reappears as a crescent on the other side, and is visible low in the southeast before sunrise. That's when we call Venus the "Morning Star" as opposed to the "Evening Star."
For most of its orbit, Venus appears in a small telescope as little more than a not-quite round "dot." In the evening sky, the planet reaches a quarter phase as it gradually increases in apparent size. The angular width increases dramatically as it becomes a slim crescent, as it is at this time.
It appears so large that some people with excellent vision and good sky conditions have detected the crescent without any optical aid.
Venus is nearly the width of Earth, at about 7,519 miles. The planet is on average, 67.2 million miles from the Sun and takes 224.7 days to go once around the Sun.
Step out around 4 or 5 a.m. to see Comet Lovejoy. Just visible to unaided eyes if the sky is dark, binoculars will give you a wonderful view. You should be able to see a bright, fuzzy "head", magnitude +4 or +5, with a short and dimmer tail pointing away from the Sun (to the upper left). The comet is slowly moving from night to night through the northeastern sky as seen before dawn. Skyandtelescope.com has a good star chart available with the path of Comet Lovejoy marked, to help you find it.
Comets are named for their discoverer. Terry Lovejoy, an amateur astronomer in Australia, first spotted this comet on September 7.
Low in the east-southeast about an hour before sunrise, look for planet Saturn. There's another comet there as well (to the left of Saturn on Dec. 7), Comet ISON, which is not as easy to see as was hoped.
Throughout the night this December, marvel at the brilliant planet Jupiter, seen in the east-northeast during the evening, and high in the southwest before dawn.
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Keep looking up!