Astronomy news for the two weeks starting Friday, May 11, 2012.
The next Skylights will appear on Friday, May 25.
The Moon starts off our fortnight in its
third quarter, the phase actually reached
the afternoon of Saturday, May 12th, with the Moon out of
sight. That morning will provide a fine view of the almost perfect
phase. Look for it between the classical figures of Aquarius and Capricornus. The remainder of our first week sees the
Moon fading in the east as a waning
crescent, new Moon finally passed on Sunday the 20th. The Moon
then switches into the west, allowing us to admire the waxing crescent. Be sure to look the evening of
Tuesday the 22nd, when the thin crescent will appear just down and
to the left of Venus. By the following evening, the thickening crescent
will be well up and to the left of the planet. Look early!
Earlier in our period, the Moon visits with Neptune on
Sunday the 13th (the Moon six degrees to the north) and with Uranus on
Wednesday the 16th.
This new Moon will produce an annular
eclipse on the evening of Sunday the 20th. (In an annular eclipse, the Moon is a bit too far
away to entirely cover the Sun, leaving a ring of bright sunlight.
Apogee, where
the Moon is farthest from Earth, takes place the day before.) Near
sunset, the path of annularity goes from northern California
through Nevada and Utah into New Mexico. Only those in the far
west get to see all of the annular portion. A large part of
western and central US and Canada, however, will witness a partial
eclipse, but with the Sun only near or during its setting. Do not
attempt to look at the Sun directly without a professionally made
filter, or use pinhole projection (shining the sunlight through a
pinhole in a piece of cardboard or paper onto a second sheet placed
behind it).
Back to the planets. Working our way from inside out,
Mercury rises in bright morning twilight and cannot really be
seen. Venus, on the other hand, is still bright in the west. But
you need now to look earlier, as the planet is preparing to swing
between us and the Sun and is therefore setting notably earlier day
by day, appearing to plunge toward the horizon. At the beginning
of our two-week period, it is still setting around 11 PM Daylight
Time. But by the end of it, Venus sets before 10 PM with twilight
still lighting the sky. Up until now, Venus has been moving
steadily to the east against the stars, more or less keeping pace
with the Sun. On Tuesday the 15th, however, the planet reverses
itself and begins westerly
retrograde motion, which will cause our familiar evening
companion to be gone by the end of the month.
Mars,
however, is still nicely with us. Fading just a bit as Earth pulls
away, the red planet is moving noticeably to the east against the
background south of the classical figure of Leo to the southeast of Regulus. Now well past the meridian to the south as darkness falls,
Mars sets around 2:30 AM or so Daylight Time. Much farther out, Jupiter makes
invisible news by passing conjunction with the Sun on Sunday the
13th. As much as anything, though, the night belongs to Saturn. Distant and moving slowly, the planet continues to
hang out to the northeast of Spica, transiting the meridian around
10:30 PM shortly after Venus sets. Saturn is then with us the rest of
the night until it sets in dawn's light.
May belongs to the Big Dipper,
which rides high in the hours before midnight. The asterism, and
the constellation to which it
belongs, Ursa Major, the Great
Bear, is along with Orion among
the sky's most beloved figures. Look at the second star in from
the end of the Dipper's handle to find bright Mizar with dimmer Alcor next to it, the two making the
Arab's Horse and Rider. Then follow the front bowl stars downward
to Polaris, which is at the end
of the handle of the Little Dipper
and closely marks the north celestial
pole. Finally, look to the southwest of the Dipper to find
three unrelated pairs of stars that make both the Bear's feet and,
in a quite different mythology, the Arab's "leaps" of the gazelle.
