Photo of the Week.. Remembering the clear blue skies
of autumn...
Astronomy news for the three week period starting
Friday, June 3, 2005.
Skylights will next appear on Friday, June 24.
Over the 21-day period covered by this version of Skylights, the
Moon goes through the first half of its monthly cycle. We begin
with the thinning crescent in the
dawn sky, pass through new Moon on Monday, June 6, through the waxing crescent to first
quarter on the night of Tuesday the 14th, then through waxing gibbous to
full Moon the night of Tuesday
the 21st, and finally to waning gibbous.
This full Moon is just short of "perfect," as it takes place less
than a day after the Sun passes the Summer Solstice, the full Moon as a result being very
close to the Winter Solstice in Sagittarius. Given the tilt of the
lunar orbit, and that the full Moon is well south of the ecliptic (the apparent solar
path), this one will appear about as low in the sky as
possible.
The evening of Wednesday, June 8, finds the crescent Moon above Venus,
which is increasingly visible in twilight in the west-northwest.
The event is followed the next night by a nice pairing of the Moon
with Saturn, all
within the confines of Gemini.
Then watch the Moon pass close to Jupiter
the night of Wednesday the 15th, the Moon, Jupiter, and the star Porrima (in Virgo) all in a line. The following evening finds the
Moon to the west of Spica, the next
night the east of the bright star. The night of Sunday the 19th,
the Moon will be to the west of Antares in Scorpius, the following night to the east of it.
With Saturn in the far northwest in the evening, the early night
sky more belongs to Jupiter to the south and southwest, the planet
setting a couple hours after midnight, shortly after Mars rises in the
southeast. On Sunday the 5th, Jupiter ceases retrograde motion and
begins once again to move to the east and back toward Spica. On
Wednesday the 15th, Uranus begins retrograde, while a day before, Pluto is
in opposition to the Sun.
Two other items dominate the period. First (as noted above) is the
passage of the Sun through the Summer Solstice in Gemini on Tuesday
the 21st at 1:46 AM CDT (2:46 AM EDT, 12:46 AM MDT, 11:46 PM June
20 PDT), at which time
astronomical summer begins in the northern hemisphere, winter
in the southern. At that moment, the Earth's northern pole will
tipped toward the Sun, the Sun will be as far north as possible
(23.4 degrees north of the celestial equator), and will shine
overhead at the Tropic of Cancer (23.4 degrees north latitude).
The day will be as long as possible in the northern hemisphere, and
as short as possible in the southern. The
midnight Sun will also shine at all points north of the Arctic
Circle (66.6 degrees north latitude).
The other item is a grand, growing gathering of planets in evening
western twilight along with Castor
and Pollux in Gemini. Watch in
mid-June as both Venus and Mercury climb the evening twilight sky,
Mercury, the faster of the two, overtaking Venus. At the same
time, Saturn descends to meet them both. The evening of Saturday
the 18th finds Saturn, Venus, and Mercury in a line the points down
and to the right. By the evening Friday the 24th, the three are
gathered into a tight knot (Saturn to the left, Mercury to the
right), with Pollux and Castor farther to the right.
While the focus here is on the sky visible from the mid-northern
hemisphere, with Arcturus and
Spica to the south in early evening, with Vega climbing the northeast, we should
keep the deep southern sky in mind. In mid-evening, Crux, the Southern Cross, one of the
grandest figures of the sky, passes the meridian out of sight for
most in the northern hemisphere, but easily visible from Hawaii and
points south. In the northern hemisphere look for the Northern
Cross -- upside-down Cygnus -- to
the east of Vega.
