SKYLIGHTS
Astronomy news for the week starting Friday, November 5, 1999.
The waning crescent Moon hovers low in the eastern dawn sky early
in the week, then passes through its new phase, when it is
temporarily invisible, the night of Sunday November 7. The waxing
crescent then pops up in western evening twilight the night of
Tuesday the 9th and grows from there toward next week's first
quarter. The night of Thursday the 11th finds it just to the right
of the Little Milk Dipper of Sagittarius, which is now fading into
twilight. The evening crescent is also near apogee, the point
where the Moon is farthest from Earth on its elliptical orbit.
The early evening is now dominated by prominent Jupiter, which is
already up in the east at sunset. Even binoculars will show its
four bright Moons. These four satellites, in order outward Io,
Europa, Ganymede, and Callisto, are really of planetary size,
Ganymede and Callisto comparable with Mercury. The innermost, Io,
is the most volcanic body in the Solar System, its sulfurous
volcanoes produced from heat generated by tides raised by giant
Jupiter. A dozen other tiny satellites also orbit the
planet.
It is Saturn that holds this week's attention, however, as the
ringed planet passes opposition with the Sun on the morning of
Saturday the 6th. Following Jupiter across the sky by about an
hour, Saturn will then rise at sunset, set at sunrise, and cross
the meridian to the south at midnight. While Saturn has even more
satellites than Jupiter, it has just one big one, Titan, which is
about the size of Ganymede and Callisto. It great claim to fame is
that it has an atmosphere, one so thick we cannot see the surface,
a surface that may contain an ocean of methane.
In the early morning, Venus grabs all the attention. Though past
its maximum brightness, its fading is barely noticeable, the
luminous planet still able to cast shadows and be seen in full
daylight. The inner planets are nearly bereft of moons. Mercury
and Venus have none at all. Ours is large, but all by itself, and
Mars has but two tiny ones that are probably captured
asteroids.
The "wet quarter" of the zodiac, reminiscent of an ancient rainy
season, parades by in early evening, beginning with Capricornus,
the "Water Goat," to the left of Sagittarius, followed by Aquarius
the "Water Bearer," and then Pisces, the Fishes. Though none of
these figures are very bright, Aquarius is well-represented by the
tight four-star "Water Jar," and Pisces by a fairly prominent
circle of stars -- the "Circlet" -- just to the east of the Water
Jar.
