Astronomy news for the week starting Friday, May 6, 2011.
Our Moon finishes up its waxing crescent
phase the early part of the week, passing its first quarter on Tuesday, May 10, as it climbs the
eastern daylight sky. It then spends the rest of Skylights' weekly
period as a waxing gibbous, spreading ever
more light upon the nighttime land. We start with the crescent to
the west of Gemini, then watch
the first quarter glide to the southwest of Regulus in Leo. The night of Thursday the 12th, look for the
waxing gibbous to shine about 20 degrees due west of Saturn in Virgo as it prepares to pass to the
south of the ringed planet. The autumnal equinox, where we find the Sun on the first
day of autumn, will lie between them.
The morning sky is the stage for a remarkable interplay of planets,
though sadly you need binoculars, good timing in dawn's light, and
a clear horizon to see it. For the next week or so, Venus, Jupiter, Mars, and Mercury (the
gang rising about 5 AM Daylight Time) will make a constantly-
shifting tightly-packed quartet with Venus the brightest, followed
by Jupiter, Mercury, then Mars. Early in the week, rising Jupiter
will be down and to the left of Venus with Mercury down and a bit
to the right of our brightest planet (which is briefly visible to
the naked eye). With Mercury at greatest western elongation on
Saturday the 7th, it and Venus will sink toward the Sun, while
Jupiter will pull away from it. Jupiter then passes conjunction
with Mercury (Jupiter 2 degrees to the north) on Tuesday the 10th,
then with Venus (Jupiter also to the north, but by just half a
degree) the next day. The morning of Wednesday the 11th, the three
will bundle into a tight pack with Jupiter now up and to the right
of Venus, with Mars farther down and to the left. As Jupiter
climbs out of twilight, the other three maintain themselves as a
close trio for much of the remainder of the month.
Watching the whole affair from the other side of the sky is lonely
Saturn, which is well up in the east at sunset (still to the
northwest of Spica), crosses the meridian to the south around 10:30 PM,
and then sets just before the planetary quartet rises.
Saturn draws the eye to Spica, then to Virgo, the star making the southern anchor of the constellation, with some of it
sprawling out to the northwest where it encounters Leo, the rest of
it going to the northeast toward Libra and Serpens,
none of it making a really distinctive figure. Among the more
obvious stars is Porrima, Gamma
Virginis (and second brightest in the constellation), which lies
about 15 degrees to the northwest of Spica and currently just about
a degree to the northwest of Saturn.