Spectacular Sky Scene Monday Evening

Every once in a while, something will appear in the night sky that will attract the attention of even those who normally don't bother looking up. It's likely to be that way on Monday evening, Dec. 1.

A slender crescent moon, just 15-percent illuminated, will appear in very close proximity to the two brightest planets in our sky, Venus and Jupiter. People who are unaware or have no advance notice will almost certainly wonder, as they cast a casual glance toward the moon on that night, what those two "large silvery stars" happen to be? Sometimes, such an occasion brings with it a sudden spike of phone calls to local planetariums, weather offices and even police precincts. Not a few of these calls excitedly inquire about "the UFOs" that are hovering in the vicinity of our natural satellite.

Very bright objects

Venus has adorned the southwestern twilight sky since late August. No other star or planet can come close to matching Venus in brilliance. During World War II, aircraft spotters sometimes mistook Venus for an enemy airplane. There were even cases in which Venus drew antiaircraft fire.

Earthlit ball

A very close conjunction of the crescent moon and a bright star or planet can be an awe-inspiring naked-eye spectacle. The English poet, critic and philosopher, Samuel Taylor Coleridge (1772-1834) used just such a celestial sight as an ominous portent in his epic, "The Rime of the Ancient Mariner." In addition, there are juxtaposed crescent moon and star symbols that have appeared on the flags of many nations, including Turkey, Pakistan, Malaysia, Algeria, Mauritania, and Tunisia.

Also on Monday evening, you may be able to see the full globe of the moon, its darkened portion glowing with a bluish-gray hue interposed between the sunlit crescent and not much darker sky. This vision is sometimes called "the old moon in the young moon's arms." Leonardo da Vinci (1452-1519) was the first to recognize it as what we now call "earthshine."

Keeping it all in perspective

Keep in mind that this head-turning display of three celestial objects crowded together will be merely an illusion of perspective: the moon will be only about 251,400 miles (403,900 km) from Earth, while Venus is nearly 371 times farther away, at 93.2 million miles (149.67 million km). Meanwhile, Jupiter is almost 2,150 times farther away than our natural satellite at 540.3 million miles (869.0 million km).

(FULL ARTICLE at Yahoo.com)

Joe Rao
Skywatching Columinst-SPACE.COM
Fri Nov 28, 10:31 am ET