Skylights featured three times on Earth Science
Picture of the Day: 1
, 2
, 3
, 4
.
Photo of the Week.. A gentle sunset announces the
coming night.
Astronomy news for the week starting Friday, May 7, 2004.
Our Moon passes its third quarter the morning of Tuesday, May 11, not far from
sunrise as it is crossing the meridian to the south, allowing a
fine view of an almost perfect division between its day (facing
east) and night. A telescopic view vividly shows the dividing
line, the "
terminator," where crater rims and central mountain peaks throw
their longest shadows, and thus stand out in bold relief. The day
before the quarter, on Monday the 10th, the Moon passes to the
south of
Neptune (in Capricornus), and
the day after the quarter to the south of
Uranus (in Aquarius, the planet
lying south of the prominent "Water Jar"). On Wednesday the 12,
the Moon will actually occult the brightest asteroid, Vesta (the only one visible to the naked eye), the
sight unfortunately seen only in the eastern hemisphere.
Bright planets gather together to create a wonderful evening vista
in the west. Venus,
brilliant and unmistakable, leads the parade. Up and to the left
of it is much dimmer, but notably reddish, Mars, while up and
to the left of Mars is Saturn, which still lies
in southern Gemini. Keep
looking to the east to find bright Jupiter
(second only to Venus), which resides two zodiacal constellations
over, in Leo. (In between is dim
Cancer with its fine open cluster,
the Beehive.) To add to the
show, down and to the right of Venus is the modestly bright star,
Elnath, which represents the
northern horn of Taurus, the
constellation being lost to twilight. In the other direction, low
in the eastern morning sky, a lucky viewer might find Mercury, which is just shy
of its greatest western elongation relative to the Sun by the end
of the week.
Two modestly bright comets now grace
the sky, Comet LINEAR in the morning dawn, Comet NEAT (both
acronyms) in evening twilight, the latter a better sight up and to
the left of Orion. Both are difficult to see in the bright glow of
residual sunlight, and binoculars are necessary.
The northern celestial pole is enclosed in Ursa Minor, the Smaller Bear, which is most
recognizable as the Little Dipper. The figure begins with Polaris, which is within a degree of
the pole, and stretches almost 20 degrees outward. At this time of
year it is beginning to stand on its handle. While the southern
pole actually lies in obscure Octans (the Octant), it is actually
surrounded by three other constellations unknown to most
northerners, Chamaeleon (the
obvious Chameleon), Apus (the Bird of Paradise),
which lie within 15 degrees of
the pole, and Mensa. Only from
near the equator of the Earth can one see both the Dipper and the
Chameleon at the same time. From the Tropic of Capricorn and
south, the Little Dipper is completely lost to sight.
