Skylights featured three times on Earth Science
Picture of the Day: 1
, 2
, 3
, 4
.
Photo of the Week.. A white sunpillar seems to burst
from a dark sloud. A sunpillar
is caused by reflection of sunlight from ice crystals in the air,
and is an upside-down version of the reflection of sunlight from
the water in a pond.
Astronomy news for the week starting Friday, April 22, 2005.
We begin the week with the Moon deep into its waxing gibbous phase
just shy of full, that phase
passed on Sunday the 24th. The remainder of the week brings the
Moon back to gibbous, though waning rather
than waxing, as it heads towards last quarter the night of April
30. The night of Friday the 22nd, the Moon will be in between Jupiter and Spica in Virgo (Jupiter to the west), and by
the following evening, the Moon will have slipped to the eastern
side of Spica. The Moon will actually occult, or pass across,
Jupiter on Friday the 22nd, but during the day in North America,
the event visible in southern Africa. The same thing happens on
Tuesday the 26th, when the Moon occults Antares in Scorpius, which can be seen only from parts of Europe,
Africa, and Asia. Look for the Moon to the west of that bright
star the night of Monday the 25th and to the east of it the
following night.
Eclipses of the Sun and Moon go in pairs. We had a curious
annular-total eclipse of the Sun at new Moon on April 8, and sure
enough, here comes an eclipse of the Moon at full (the only phase at
which the Moon can enter the Earth's shadow) the morning of
Saturday the 24th. It is not one to get up for, however, as it is
"penumbral," the Moon passing through only the fuzzy region of
partial Earth-shadow. From any point on the Moon, an observer
would see the Earth take a bite out of the Sun, but
some sunlight would be visible. The result is that the Moon dims
just a little, the shading quite difficult to see. The event, such
as it is, is fully visible only in the western US and Canada, maximum
dimming taking place at 2:55 AM Pacific Daylight Time.
Jupiter and Saturn still dominate the sky, with Saturn in Gemini to the northwest as evening
falls and Jupiter in the southeast above Spica in Virgo, the giant
planet transiting the meridian shortly before midnight daylight
time. The late morning brings us Mars, which rises
in the southeast in eastern Capricornus at 3:30 AM, and Mercury, which
reaches greatest western elongation on Tuesday the 26th. Bright
twilight will make the little planet difficult to find, however.
Horses, or fanciful horse-like creatures, can be found scattered
across the sky. In autumn evenings we easily spot Pegasus (the Flying Horse) with
his Great Square, and not too
far from it, with some effort, can spy out Equuleus, the Little Horse. In winter and early spring
the modern constellation Monoceros,
the Unicorn, can be found to the east of Orion, while in summer the centaur Sagittarius gallops across the southern horizon. If
you are far enough south, Centaurus, the sky's classic Centaur, can be found to
the south of Spica in Virgo.
