Photo of the Week. Filtered sunlight. See the rest
of the series: 2, 3, and 4.
Astronomy news for the week starting Friday, August 12, 2011.
We begin our week with the Moon in the last stage of its waxing gibbous phase, which ends with full Moon on Saturday, August
13th, during the day with the Moon out of sight. That evening it
will thus be barely in the first stage of the waning gibbous, though for all intents it
will appear quite full. The next day it will pass several degrees
north of Neptune,
followed by a Uranian visit on
Wednesday the 17th, both passages of no visibility or consequence.
The evening of Thursday the 18th, though, is more promising, with
the Moon a dozen or so degrees to the west of
Jupiter as it prepares to pass north of the planet next Friday
night. Fading away during the week in the waning gibbous, the Moon
does not pass third quarter until Saturday
the 21st. As the week ends, on Thursday the 18th, it goes through
apogee where
it is farthest from the Earth.
Though technically still with us, Saturn is so far over in the west as the sky
darkens that it is effectively gone, setting just half an hour
after the end of twilight. Stars and planets become very difficult
to see when near the horizon in any case because of increasing
obscuration by the Earth's light-absorbing atmosphere. Jupiter, however, is beautifully positioned, rising
around 11 PM Daylight Time in south central Aries to the south of the classical figure. It is then
with us the rest of the night, not transiting the meridian until sunrise. Mars next enters the scene by rising in the
northeast around 2:30 AM beautifully set against the stars of
southern Gemini.
Finally, by odd coincidence
Venus and
Mercury invisibly pass conjunction with the
Sun on the same day, on Tuesday the 16th, within 13 hours of
each other, but on opposite sides of the Sun. Venus is first,
going through superior conjunction (on the other side of the Sun)
followed by Mercury passing inferior conjunction (more or less
between us and the Sun, though well to the south of the solar disk
and not passing across it).
Repeating from last week: The night of August 12 and the morning of
the 13th are set for the maximum of the
Perseid meteor shower, the meteoroids the flakings of Comet Swift-Tuttle
(a small icy body that is slowly dissolving under the action of
sunlight), which has a 133-year period, was discovered in 1862, and
last came by in 1992. But don't much bother with the shower this
year, as the meteors (which through a perspective effect seem to
emanate from the constellation
Perseus), will be hidden by the light of the nearly-full Moon.
In the early evening after sunset, Scorpius, the celestial Scorpion, dominates the far
southern sky. Look then to the north of it for the giant pentagon
that makes Ophiuchus, the
Serpent Bearer, wrapped by Serpens, the only constellation of the sky that comes
in two parts the Head (Serpens Caput) to the west of Ophiuchus and
the Tail (Serpens Cauda) to the east.
