Photo of the Week. A study in light and shadow
against the blue sky.
Astronomy news for the week starting Friday, October 26, 2007.
Keep your eye out for Periodic Comet
Holmes, which has undergone a huge outburst, and as of last
week shone at second-third magnitude in Perseus just to the east of Alpha Persei. The reason for the highly
unusual outburst is not known. To the eye, the comet appears
starlike with no tail.
Having just passed its full phase, the
Moon begins our week as a fat waning
gibbous as it heads toward third
quarter on Thursday, November 1. It passes three degrees north
of Mars
during the afternoon of Tuesday, October 30, and therefore will be
seen to the west of the planet the night of Monday the 29th, and to
the east of it the following night. The lunar orbit is tilted to
the solar path, the ecliptic, by
about five degrees. The current orientation of the orbit (which
wobbles over an 18.6 year period) is now bringing the Moon rather
well south of the winter solstice
in Sagittarius and to the north of
the summer solstice in Gemini. As it transits the meridian the night of the 29th, the Moon
will thus be (for mid-northern hemisphere observers) especially
high in the sky.
Mars, rising in
southern Gemini around 9:30 PM Daylight Time, is becoming a fine
evening object set among the glorious stars to the north of Orion. Compare its color to the
orangy "red giant" stars Aldebaran in Taurus and Pollux in Gemini (the southeastern of
Gemini's two bright stars). Over the week-long period, you can see
Mars move to the east against the background by more than a degree.
It's Venus, though, that takes center stage.
Still rising around 3:30 AM, the brilliant planet attains its
greatest western elongation relative to the Sun (46 degrees to the
west of the Sun) on the morning of Sunday the 28th. As it
maintains its position relative to the Sun, Venus slips further to
the east against the background, moving inexorably from Leo toward Virgo, which it will formally enter on November 3.
To the west of Venus, much dimmer (though still bright) Saturn rises
about an hour earlier in Leo to the east of Regulus. Watch as the two planets
slowly separate, Saturn pulling steadily to the west of Venus. On
the other side of the sky,
Jupiter, still in southern Ophiuchus to the northeast of Antares, sinks more and more into
evening's dusk, setting by 8:30 PM. It will be gone before year's
end, so enjoy it now.
There is still time to find a dark sky to see the Milky Way plunging down from Cygnus toward Sagittarius. Among the best sights is the special glow
along the way to the southwest of Aquila that marks the location of the modern constellationScutum, the Shield. It's your entry way to the vast star clouds of the Archer, below which lies the graceful
curve of Corona Australis, the
Southern Crown.
