Photo of the Week. Perhaps the lovely windswept
cirrus will blow away to give us a clear night.
Astronomy news for the week starting Friday, May 4, 2007.
The Moon having passed full last May 2,
the night skies begin to darken once again, though it will be later
in the week before we see any real difference. At first the Moon
will wane
through its gibbous phase, then pass third quarter the
night of Wednesday the 9th, roughly about the time of Moonrise in
North America. With the Sun now halfway to the Summer Solstice, the third quarter, 90
degrees "behind" (to the west of) the Sun, will shine among the dim
stars of Capricornus. In what is
left of the remainder of the week, the Moon will wane
as a fat crescent. Look the morning of Saturday the 5th to see the
gibbous Moon passing some 6 degrees to the south of Jupiter.
Even people familiar with the sky tend to lose sight of the third
dimension. While Jupiter and the Moon seem painted on the dome of
the sky, they are at vastly different distances, the Moon a mere
quarter million miles (or so) away, Jupiter 1500 times farther! On
the morning of Thursday the 10th, the Moon then takes on much
dimmer and more-distant Uranus (which is
at the moment 4.6 times farther than Jupiter).
Evening's Venus
rises yet higher and sets yet later in the northwest, as it
does not finally go down until just after 11:30 PM Daylight Time,
the planet giving us one of the best apparitions possible. Venus
has a long-term, eight year, cycle in which it repeats its
apparitions. That is, in 1999 it
appeared much as it does now, while in 2015 you'll see much the
same again. This brightest of the "ancient planets" is now nicely
paired with the faintest, Saturn
. Slowly approaching each other, they are heading for a very
nice conjunction on July 1, when they will be just under a degree
apart. In western skies to the west of Leo, the ringed planet remains up until 2:30 AM,
setting about half an hour before Jupiter (now rising at 10:30 PM)
crosses the meridian.
Lying between classical Scorpius
and Sagittarius, Jupiter is
actually moving slowly against the background of the "13th
constellation" of the Zodiac,
Ophiuchus. Very much NOT part
of the classical Zodiac, the modern (and arbitrary) boundaries of
the giant constellation cut across the ecliptic. The Sun is actually
"in Ophiuchus" (roughly November 30 to December 18) for longer than
it is "in Scorpius" (November 24 to 30).
As we move into May,
Mars slowly begins to break away from twilight. Though still
elusive, the red planet is at least rising almost half an hour
before the onset of dawn.
Sunday the 6th marks the peak of the Eta Aquarid meteor
shower (named after a star close
to the apparent radiant from which the meteors seem to come). But
don't bother looking. The meteors from the debris of Halley's
Comet are few and far between and will be wiped out by a nearly
full Moon.
Here comes Centaurus. The giant
constellation is now making serious inroads into the far southern
sky. Look far to the south down below Virgo's Spica to find
its very top stars, which will be skirting the horizon for middle
North America, its two luminaries Rigil Kentaurus (Alpha Centauri, the closest star to
Earth) and Hadar (Beta), far out of
sight except for far southern latitudes.
