Astronomy news for the week starting Friday, February 25, 2011.
With the last (third) quarter immediately
behind us, the Moon launches into
its waning crescent phase, which will
occupy the week until it goes through new next Friday, March 4.
Your last glimpse of the ultrathin crescent will be the morning of
Thursday the 3rd. Be sure to get up early enough to be charmed by
the crescent playing with
Venus. The morning of Monday, February 28th, the Moon will shine up and
to the right of the brilliant planet, while by the next morning they
will have switched places, the Moon glowing down and to the left of the
second world from the Sun.
"Early" does define Venus, as it rises
around 4:30 AM, about half an hour in advance of twilight. Yet
there is a saving grace, as the planet is so bright that you can
easily see it -- and its relation to the Moon -- in bright twilight
shortly before sunrise. By the time Venus comes up, Saturn is already
well over in the west, having passed the meridian to the south around 2:30 AM.
The pairing with Spica, which lies
just to the southeast of Saturn, makes for a striking sight.
Becoming ever more an evening object, the ringed planet now rises
just after 8:30 PM, only half an hour after Jupiter sets. So to
see the "big guy" you need to look plenty early, just after the sky
begins to darken and the giant planet gets lost behind the trees.
In part, though, Jupiter's loss is as much the fault of the end of
twilight getting later (now rather well after 7 PM) as the Sun slowly moves north, advancing
toward the Vernal Equinox and the
first day of northern spring.
Again admire Orion, which is now
crossing the meridian to the south as the sky fully darkens.
Beneath the mythical Hunter is a pair of distorted joined boxes
that represent Lepus the Hare,
and below that is a lovely small flat triangle that makes the
modern constellation of Columba, the Dove, meant to
commemorate that of Noah. Commonly lost to trees, buildings, and
horizon haze, Columba is a full 35 degrees south of the celestial equator, and from mid-northern
latitudes crosses the meridian only 10-20 degrees above the
southern horizon. Columba is most
famed for Mu Columbae, one of the
first known "runaway" stars, which result from interactions between
double stars (as is
apparently the case for Mu Col) or are ejected from doubles when
one member explodes as an off-center supernova.