Photo of the Week. The Milky Way in Sagittarius,
holds the center of the Galaxy,
obscured by the dense dust clouds near lower center. (The streak
at upper left is a satellite trail; the cluster called Messier 7 sits distinctively at lower
left.)
Astronomy news for the week starting Friday, July 30, 2010.
The Moon fades away this week, starting in the waning gibbous phase, then passing third quarter the night of Monday, August 2,
about the time of Moonrise in North America, making for a fine
sight. The remainder of the week sees it in the waning crescent phase, new Moon not reached
until next week. Oddly, sitting rather high along the ecliptic path, it visits no
planets at all.
The lack of lunar activity is more than made up for by the parade
of evening planets, the least of which is nearly invisible Mercury, which passes
greatest eastern elongation with the
Sun on the night of Friday the 6th, rather well out of
visibility. The real sight belongs to
Venus,
Saturn, and
Mars. Not too long ago they were stretched out on a line. Now
the night of Sunday the 1st (give or take a day or two) look to see
them in a fine flat triangle. Venus will be at the lower right
apex, while Saturn and Mars make the left-hand end, brighter Saturn
on top, the color contrast with Mars rather obvious.
The will continue to dance with one another the remainder of the week.
Mars and Saturn come into formal conjunction during the day on
Sunday, August 1, just two degrees apart. As July comes to a
close, faster moving Mars will be to the west of Saturn, while as
August begins the two will have slightly switched places. Mars and
Saturn will then point up and to the right to Denebola in Leo, while up and to the left will be Porrima in Virgo. But look early, as the planetary clump sets
early at the end of twilight, about 10 PM. Needless to say, a good
flat western horizon is essential.
But not all is lost in the after-dark hours, as with the setting of
the gang of three, giant and very bright
Jupiter rises almost due east within the confines of western Pisces. Now slowly moving
westerly against the stars, Jupiter takes just under 12 years to go
around the Sun, thus on the average visiting a different Zodiacal constellation each annum.
This year it is Pisces' turn to
host the King (barring, of course, the Sun) of the Solar
System.
With the Moon getting out of the way, the southern sky grabs the
week's attention. The great curve of Scorpius south of bright Antares hits the meridian to the south around 9 PM, with
the Little Milk Dipper of Sagittarius right behind it to the
east. Below them is a curve of lesser-known constellations visible from southern
climes that starts in the west with ancient Lupus the Wolf, then goes to the east with Norma (the Square), Ara (the Altar), Telescopium (the obvious Telescope), and finally, under
Sagittarius, the graceful curve of Corona Australis (the Southern Crown).
