Skylights featured five times on Earth Science
Picture of the Day: 1
, 2
, 3
, 4
, 5
Photo of the Week. A first-quarter Moon (its
direction reversed from that seen from the northern hemisphere)
hovers above Antarctic waters, the cold sea filled with ice floes.
Though the picture was taken at 1:15 AM, the Antarctic summer is
filled with light from a near-circumpolar Sun. (Lemaire
Channel/Pleneau Island, 65 degrees south, 62.5 degrees west,
courtesy of Caroline Badger.)
Astronomy news for the week starting Friday, April 14, 2006.
For most of the week, our Moon wanes in it
gibbous phase, finally passing third
quarter on the last night, Thursday, April 20, rather well
before Moonrise in North America. Be sure to watch the night of
Friday the 14th when the just-past-full Moon will be just to the
west of Jupiter, with Zubenelgenubi (one of our favorite
star names) rather invisibly in between them. The following night
the Moon will be well to the east of Jupiter, while the morning of
Monday the 17th sees the Moon passing just south of Antares in Scorpius. The Moon will actually occult the star as
seen from southern South America. Such occultations can be used to
measure the angular diameters of stars, though Antares has been
studied so thoroughly that the event is not terribly important.
All following times are "Daylight." Now rising in the southeast at
9 PM, Jupiter (in Libra)
dominates the late evening sky. To the west of it lie both Saturn and Mars. Saturn,
slowly moving through Cancer still
near the Beehive Cluster,
transits the meridian at sunset, and by the time it is visible has
moved into the western sky, its northerly position delaying its
setting time until 3 AM. Mars, to the west of Saturn, moves into
Gemini just north (about 1.5
degrees) of the Summer Solstice.
About as far north as it can get, the red planet still does not set
until local midnight, or 1 AM. Stay up late, or get up early, and
you can admire the brightest of all planets,
Venus. Still shining at minus fourth magnitude, and visible in
a clear daylight blue sky, the planet rises just about as morning
twilight commences (4:30 AM). Halfway between Venus-rise and
Sunrise, Mercury pokes its
head up, though it is so close to the twilight horizon it is
difficult to see. On Tuesday the 18th, Venus passes just 0.3
degree to the north of Uranus.
The Lyrid meteor
shower (the radiant in Lyra)
grows during the late-week morning hours. Though not maximizing
until the morning of Saturday the 22nd (with a dark-sky rate of 10-15
meteors per hour), you may still see a few.
As mighty Orion slips away to the
west, so do its various companions, which include Canis Major (the Larger Dog) with the
sky's brightest star, Sirius, Canis Minor (the Smaller Dog) with Procyon, and below the Hunter,
little-appreciated Lepus the
Hare, which contains a number of interesting objects that include
one of the reddest stars of the sky, "Hind's Crimson Star," the
long-period variable R Leporis.
