Skylights featured three times on Earth Science
Picture of the Day: 1
, 2
, 3
, 4
.
Photo of the Week.. Mars confronts the nearly-full
Moon on September 8, 2003. Compare with the July 2003 waning gibbous conjunction.
Astronomy news for the week starting Friday, October 10, 2003.
We begin the week with the Moon
just past its full phase. The entire rest of the week sees
our companion waning through gibbous as it approaches its third
quarter next Saturday, the 18th. This time of year, following the
"Hunter's Moon," the Moon rises only about a half an hour later
each night. The reverse happens after the full Moons of spring,
when the delay is nearly an hour and a half, and the waning gibbous
disappears quickly from the early evening sky, all the result of
differing angles of the ecliptic to the horizon at different times
of the year.
Four planets are in various stages of visibility. The toughest of
them to see is Venus. In spite of its continuing brilliance, it
is still just clearing the Sun after its superior conjunction last
August, and sets in bright evening twilight. By mid-November it
will be obvious in the southwest after sundown. By far the most
prominent is faithful Mars, which from
our northern vantage point shines brightly in the southern evening
sky. Slowly falling behind the Earth in its orbit, the red planet
is now moving easterly against the stellar background south of the
"Y"-shaped "Water Jar" of Aquarius.
An hour after Mars crosses the meridian to the south (around 10 PM
daylight time), the most distant of the "ancient planets,"
Saturn, rises in Gemini.
The Moon will be just to the north of it the morning of Friday, the
17th. And then about an hour after Mars sets (3 AM Daylight Time),
bright
Jupiter rises. Jupiter takes just under 12 years to make a
full circuit of the Sun, and therefore on the average takes a year
to move through any given constellation of the Zodiac. Last year
the king of the planets dominated dim Cancer. Now it meets a fine rival in bright Leo, the planet currently located
south of the center of the prominent constellation. Next year, we
will find it in Virgo.
As twilight disappears into the western sky, find magnificent Cygnus nearly overhead (as seen from
moderate northern locations), topped at its northern end by first
magnitude Deneb. To the west lies
pretty Lyra with bright Vega, to the east one of the dimmer
constellations of the sky, modern Lacerta, the Lizard. Moving farther to the east,
rising is the broad sweep of stars that represents Andromeda, the figure clearly
announcing the advancement of fall and chilly northern weather.
South of Cygnus lies Aquila with
Altair, the three stars (Deneb,
Vega, and Altair) making the Summer Triangle. Between Cygnus and Aquila find two
small but nicely prominent constellations, Delphinus (the Dolphin), which looks something like a
hand with a pointing finger, and Sagitta (the Arrow), which looks for all the world like
what it is named after, the little figure sometimes thought of as
an arrow shot by Hercules, the
great Hero lying to the west of Lyra.
