SKYLIGHTS
Astronomy news for the five days starting Sunday, August 15,
1999.
Skylights will resume its normal schedule on Friday, August 20.
Following its eclipse of the Sun last Wednesday, AUGUST 11th
(please forgive last week's typo), the Moon spends the first part
of the week in its waxing crescent phase and will pass first
quarter on Wednesday, August 18, the day before it passes apogee,
its farthest point from the Earth. The night of the first quarter
also finds the Moon just to the northeast of Mars.
The red planet is now working its way easterly through the stars of
Libra to the southeast of Zubenelgenubi (the "southern claw" of
Scorpius), providing a good chance to locate the star.
Zubeneschamali, the "northern claw," can be found up and to the
left of Zubenelgenubi. Down and to the left is Mars's namesake
Antares (meaning "like Ares," the Greek version of the god of war).
The planet will pass three degrees north of Antares the morning of
September 17.
With Venus's departure, Mars is the only planet left to the evening
sky. Venus will be in inferior conjunction, when it is between us
and the Sun, on Friday the 20th. The alignment will not be exact,
however, the planet passing eight degrees south of the solar
center. Only on rare occasion is Venus seen against the Sun: not
at all in the twentieth century, and not until June 8, 2004.
Mercury, on the other hand, transits the Sun much more frequently,
the next such passage to be on November 15th of this year. Such
events can be dangerous to watch as the Sun is so bright. The only
really safe way is by projecting the image with a telescope.
Look to the northern sky now to see the Dipper falling to the
northwest. Opposite, in the northeast is the first suggestion of
the coming fall, Cassiopeia, the "W" shape quite prominent even in
a bright sky. Up and to the left is the dim pentagon of Cepheus,
in mythology husband to Cassiopeia, the two the parents of
Andromeda, who, with its great nebula (the Andromeda galaxy) will
shortly be rising during the early evening hours. At the far
southern corner of Cepheus, is one of the most famed stars in the
sky, Delta Cephei. It is the foremost of a class of variable stars
called Cepheids. Location of Cepheids in other galaxies allows us
to tell how far away the galaxies are, and so the stars are
important for measuring the rate of expansion, and the age, of the
Universe.
