Photo of the Week. Who says green and blue don't go
together?
Astronomy news for the week starting Friday, February 12, 2010.
We start the week in the "dark of the Moon," as our companion goes
through its new phase the evening of Saturday, February 13, the waning crescent too far gone to be visible
that morning. The following day, is of course Valentine's Day.
It's a non-astronomical holiday, but happy Valentine's to everybody
anyway. Look then the next night, that of Monday the 15th, to see
waxing crescent in southwestern evening
twilight. Filled with diminising Earthlight, the Moon subsequently
grows toward first quarter, that phase
not reached until early next week (Sunday the 21st). The Moon
passes apogee
(where it is farthest from the Earth) almost exactly a day before
the new phase, which will weaken the highest tides at the coasts
(tides dependent on the inverse cube of the lunar distance).
Jupiter is
now difficult to see in bright southwestern evening twilight and is
for all purposes gone from view. But take heart, as it is
gradually being replaced by Venus. The two make a
close, though nearly invisible, companionship at mid-month. Watch
during February's remainder to get your first glimpse of the second
planet from the Sun.
That pretty much leaves the planetary sky to Mars and Saturn. Already well up at
sunset, the red planet crosses the meridian to the south around 11 PM among
the stars of western Cancer between
the Beehive Cluster and the Pollux-Castor pair of Gemini. Well before Mars transits
the meridian, at about 8:30 PM, Saturn rises in Virgo some four degrees to the east
of the Autumnal Equinox rather
marking the spot where we find the Sun on the first day of autumn.
In invisible planetary news, Neptune
celebrates Valentine's Day by passing conjunction with the
Sun.
Looking deeper into the sky, the asteroid Vesta makes a fine appearance as it passes
opposition with the Sun on Wednesday the 17th. Though the fourth
asteroid
discovered, and with a diameter of 510 kilometers (317 miles) the
third largest, Vesta is nevertheless the brightest of the bunch,
and near opposition is actually visible to the naked eye, though
binoculars are a far better choice. The asteroid, part of a debris
belt between Mars and Jupiter, spends much of February and March
moving retrograde through the Sickle of
Leo. The night of opposition, sixth magnitude Vesta is easily
found just to the south of second magnitude Algieba, Gamma Leonis, the Sickle's
second brightest star, indeed right between Algieba and the fifth
magnitude star 40 Leonis, which lies just under half a degree below
its brighter second-magnitude neighbor. This is one of the best
chances you will ever have to see an asteroid "live."
While spring may be near, the winter constellations still hold forth in the
early-to-mid evenings. Look for the pentagon of Auriga nearly overhead in mid-
temperate latitudes. Its southernmost star, Gamma Aurigae,
actually in Taurus, also serves as the Bull's northern horn, and is
more formally known as Elnath, or
Beta Tauri. To the south of course is one of the greatest figures
of the sky, Orion, the Hunter.
