Skylights featured three times on Earth Science
Picture of the Day: 1
, 2
, 3
, 4
.
Photo of the Week.. Dark storms give way to clear
skies.
Astronomy news for the week starting Friday, September 10,
2004.
Our Moon wanes through its
crescent phase the early part of the week, descending each morning
closer to the eastern horizon, finally passing the new phase on
Tuesday the 14th. The morning of Sunday the 12th will present a
special sight: the Moon tucked within the sickle of Leo, the classic zodiacal constellation that is now
clearing the Sun. The evening of the 14th the Moon will not have
cleared the Sun enough to be seen in the evening sky, but by the
night of Wednesday the 15th look for the slim crescent glowing in western
twilight.
This appears to be something of a "small body" week. The morning
of Sunday September 12, the Moon will hang almost directly above
little Mercury
in the dawn sky, with the star Regulus in between the two, the
bright twilight making observation quite difficult. Then on
Wednesday the 15th, Mars quite invisibly passes conjunction with the Sun
and thus swings into the morning sky. It will not, however, be
visible in growing dawn until mid October. Moving on to even
smaller bodies, two of the first four asteroids hit the
headlines. The night of Sunday, the 12th, Ceres (the
largest and first discovered) passes conjunction with the Sun.
Only two hours later, Vesta, the brightest asteroid (actually visible to
the naked eye) passes solar opposition. Smaller than any of the
planets, Ceres has a diameter of only 915 kilometers (570 miles,
just a quarter the size of the Moon), while Vesta is but 55 percent
as large (but brighter because of higher reflectivity).
Larger bodies celebrate the morning sky, where you can admire
wonderful
Venus, which is still rising around 3 AM Daylight Time, and
fainter (but still bright)
Saturn, which lies above and to the right of Venus and pointed
downward to by Castor and Pollux in Gemini.
Look for Sagittarius now low on the
meridian to the south in early evening. Many constellations
contain smaller beloved "asterisms," the most famed the Big Dipper of Ursa Major. Sagittarius is graced with not one, but
two. The most notable is the upside-down (from our northern
perspective) five-star "Little Milk Dipper," the name coming from
its setting in the Milky
Way. Add the stars to the west, and you get the "Teapot."
Then look to an interesting gaggle of stars farther to the south.
Beneath the Teapot is the graceful curve of Corona Australis, the Southern Crown, while down and to
the left are Sagittarius's Alpha
and Beta stars, which are
curiously far from the brightest of the constellation. Farther
south yet is modern dim Telescopium
(the Telescope), while over to the west underneath the curve of Scorpius's tail is Ara, the Altar, which is lost below
the horizon to those above about 30 degrees north latitude.
