Skylights featured five times on Earth Science
Picture of the Day: 1
, 2
, 3
, 4
, 5
Photo of the Week. Vesta, the brightest asteroid and
the fourth found, 500 kilometers in diameter and averaging 2.4
times Earth's distance from the Sun, moves through central Gemini on January 21, 2006.
Occasionally visible to the naked eye, here it shines at magnitude
6.6, just fainter than the formal limit. Castor and Pollux shine
at far left, Castor on top.
Astronomy news for the week starting Friday, February 17, 2006.
The Moon begins our week in its waning gibbous phase, passes third
quarter the night of Monday, February 20 (about the time of
Moonrise in North America), and thereafter wanes as a thinning crescent, rising ever
later. The night of Friday the 17th sees the Moon rising just to
the east of the star Spica in Virgo. Then take a look as the Moon
lies to the southwest of Jupiter
the morning of Sunday the 19th, and to the southeast of the planet
the following morning, before plowing down through the heart of Scorpius. The morning of Tuesday the
21st, the Moon will be just to the west of Antares, close, though not (for
those of us in North America) replicating the more intimate passage of last month. (The star
is occulted as seen from Australia, while Spica is earlier occulted
as seen from parts of Africa.) Finally, the morning of Friday the 24th,
the waning crescent can be seen down and to the right of Venus.
Venus tops the planetary scene, as on Friday the 17th it
reaches its greatest brilliancy of the year. While seen as a
crescent through the telescope (the current positioning causing
us to view mostly the nighttime side and just a piece of the
daytime side), Venus is so close that it now reflects its maximum
light to us. The fading will for a long time be un-noticeable.
Rising now in a dark sky just before 4:30 AM, the planet will
for a time get
higher before dawn takes over (the combination of Venus
against growing twilight glorious to see). Be sure also to admire
Jupiter. Now rising around midnight in Libra, the giant planet is making
the transition to the evening and crossing the meridian to the
south at daybreak, giving the morning sky two great lights.
Early evening gives us another pair of planets to watch. Moving
into mid-evening's western sky,
Mars (in Taurus) transits at
sunset, but does not set until past 1 AM, after Jupiter rises. Far
to the east is Saturn, in Cancer, which
transits to the south about 10:30 PM and lies near the Beehive cluster (Mars, in
parallel, visiting the Pleiades). If you have a clear western horizon, in
fading twilight you might also spot Mercury, which is making
its winter appearance, its maximum eastern elongation (18 degrees)
taking place on Thursday the 23rd.
Again we look to mighty Orion,
which in mid-evening stands midway up the southern sky, the
constellation filled with brilliant blue-white stars and bejewelled
with one reddish one, the supergiant Betelgeuse. Many of the
constellation's stars share their place and time with each other as
part of a loose, physically-related, "association." Scorpius (which holds Antares, the other bright red
supergiant of the sky), Centaurus, and Perseus
are similar. Gradually, as spring approaches, the Hunter will
tread to the west, he and his bright entourage to be taken over --
temporarily (he will be back) -- by the Sun.
