Photo of the Week.. The setting Sun illuminates the
rocky coast of the US state of Maine. Photo by Lauren Brewer.
Astronomy news for the short week starting Sunday, August 23,
Skylights now resumes its normal schedule.
We lose the evening Moon this week, as our companion wanes through
its gibbous phase on its way to third quarter next
Friday, August 30. It passes through apogee, where it is farthest
from the Earth, about in the middle, on Monday the 26th. Climbing
north along the ecliptic, the Moon crosses the celestial equator at
about the same time, heading for Taurus, where Saturn resides.
The evening sky now holds but one obvious planet, Venus, easily seen rather low in western
evening twilight, the planet still brightening as it gets closer to
the Earth. Still moving eastward against the starry background,
Venus is taking a bead on Spica in
Virgo, and will make a close pass
to it the end of the month. The morning sky holds more, both
Saturn and Jupiter.
Saturn, ever so slowly moving to the east against the stars, is now
close to Zeta Tauri, the star
that makes one of the outstretched horns of the zodiacal Bull.
Jupiter, on the other hand, has shifted over from Gemini into the next constellation
of the Zodiac, Cancer, a dim figure
that contains one outstanding treasure, the Beehive
Cluster. Saturn is now rising just after 1 AM Daylight Time,
while Jupiter follows some time later, rising about 4 AM, before
twilight begins to brighten the eastern sky. Just look for the
brightest thing you can see. In a dark sky, let Jupiter draw your
eyes to the Beehive, which will be just to the northeast of the
Going from bright to dim, really dim (800 times fainter than the
human eye can see alone and 250 times fainter than Neptune), Pluto begins
retrograde motion on Tuesday, the 27th. Highly inclined to the
ecliptic, the outermost of the planets now lies well off the
ecliptic, even the Zodiac, against the stars of southern Ophiuchus (the Serpent
Bearer). A curious body, it is
trapped by Neptune in a gravitational "resonance," Pluto going
around the Sun twice for every time Neptune orbits three times.
Pluto keeps moving in and out of "planet" status. In fact, it is
a fascinating body that appears to have been stuck in some kind of
transitional state between the huge host of comet
cores that lie in a thick disk (the Kuiper
belt) beyond Neptune, and a major planet like Neptune itself.
In a sense, Pluto is a planetary core, a body that would have been
a planet, accumulating from huge numbers of primitive cometary
bodies, but ran out of raw material.
People in mid-northern latitudes will see the squarish head of Draco the Dragon to the north of the
overhead point in early evening. Draw a line to the south, and it
will pass just to the east of Ophiuchus, indeed into the eastern
half of Serpens, the Serpent,
who wraps tightly about the Serpent Bearer.