SKYLIGHTS
Astronomy news for the week starting Friday, July 23,
1999.
The Moon heads towards full early this week, the phase reached on
Wednesday, the 28th. At that time, on the morning of the 28th, the
Moon will clip the top of the shadow of the Earth and we will see
a partial eclipse of the Moon. At maximum, about 40% of the lunar
surface will be covered by the Earth's curved shadow. The event,
which takes place near moonset in the early morning hours for North
America, will not be visible on the east coast. Observers in the
central US and Canada can see the Moon enter the shadow in twilight
at 5:22 AM Central Time, but the
Sun -- then opposite the Moon -- will rise before central eclipse.
On the west coast nearly the whole eclipse will be visible,
beginning at 3:22 AM PST, ending at 5:46. In a dark sky, the
eclipsed portion is always visible because of light cast into the
shadow by the Earth's atmosphere. The next lunar eclipse, which
will be total and beautifully visible in North America, will take
place the night of January 20, 2000.
The Sun has been catching up to Venus ever since its greatest
elongation on June 11. It will now catch up much faster as Venus
reverses its direction against the background stars. The night
before the eclipse, on Tuesday the 27th, Venus enters its
retrograde or westerly motion as it prepares to swing between us
and the Sun on August 20. Now visible low in the west near the end
of twilight, the planet will disappear quickly from the nighttime
sky only to pop up just as quickly in the morning sky. Red Mars,
however, is still nicely with us in the southwestern sky as it
moves away from Spica in Virgo and toward its namesake Antares in
Scorpius. The evening also holds Uranus, visible as a dim sixth
magnitude starlike object in eastern Capricornus. Just a bit to
the west of it lies telescopic Neptune, which will be in opposition
to the Sun on Monday, the 26th. The morning hours are now glorious
with Jupiter and Saturn below and to the left of the Great Square
of Pegasus.
Though the full Moon will wipe out the sky's fainter stars, those
of first magnitude still shine through. In the evening, look for
the orange giant star Arcturus in the west, blue-white Spica to the
southwest, and to the south the great red supergiant Antares. To
the east in the evening the Summer Triangle of Vega, Deneb, and
Altair climb the sky, Vega only a hair dimmer than Arcturus, the
two ranking number four and five in apparent brightness, the three
brightest (Sirius, Canopus, and Alpha Centauri) denizens of the
southern hemisphere.
