Astronomy news for the week starting Friday, July 2, 2010.
Our constant Moon begins the week in the late stages of its waning gibbous phase as it heads towards
its third quarter to help celebrate the
Fourth of July. Look for the "perfect" quarter in the eastern
morning sky during daylight. The Moon then spends the rest of the
week fading away in the waning crescent,
as it heads towards new next week and a
total solar eclipse on July 11 that will be visible on a long
track across the Pacific Ocean (and that misses North America
altogether). The waning crescent will spend two days making a nice
pairing with bright Jupiter. The morning of Saturday the 3rd, look
for the planet to the southeast of the Moon, the following night to
the southwest of it (the actual conjunction taking place the
evening of the 3rd and out of sight). Just five hours before, the
Moon passes north of Uranus, the two
planets still very much hanging out together.
Earth makes
more news than anything else, when about the time of sunrise on
Tuesday the 6th, it -- and we -- pass orbital aphelion, where we
are farthest from the Sun, at a
distance of 152,096,000 kilometers, or 94,508,000 miles, 1.7
percent farther than the average. Since we are farthest from the
Sun during North American summer, distance obviously has little to
do with the seasons, which are
caused by the 23.4 degree tilt of the rotation axis relative to the
orbital. All things equal, variation in distance makes the
southern hemisphere seasons a bit more extreme than the northern
ones, but the distribution of oceans in the south pretty much
negates the effect.
Venus still shines brightly in the western evening sky as it
converges on Leo's Regulus, which it will pass the
night of Friday the 9th (the planet still not setting until after
the end of evening twilight). A bit to the east, look for reddish Mars (which sets less
than an hour after Venus), then farther along find
Saturn. Still hanging out in Virgo between Regulus and Spica, the ringed planet is just short
of three degrees to the north of the Autumnal Equinox. As Saturn drops below the horizon at
midnight Daylight Time, opposing Jupiter rises just a bit to the
east of the VERNAL equinox in western Pisces. Except for the
crescent Moon, the giant planet then proceeds to dominate the
morning sky.
It's a perfect time to find and admire Scorpius, one of the few constellations that actually looks
like what it is named for. Look for bright Antares to the south around 11 PM,
the reddish supergiant lying at the
heart of the graceful curve of bright stars that makes the
celestial Scorpion, Orion's nemesis. To the east is the
distinctive Little Milk Dipper of
Sagittarius.
