Photo of the Week. Blue sky enhanced by a twisted
tree.
Astronomy news for the week starting Friday, August 9, 2013.
The Moon begins our
week in its waxing crescent phase, which
ends with first quarter the morning of
Wednesday, August 14th. The night of Tuesday the 13th, the Moon
will be slightly shy of the quarter, while the following night it
will be just a bit past that phase and into the waxing gibbous, which occupies the
remainder of the week. The evening of Friday the 9th, the Moon
will make a fine passage in western twilight beneath Venus, while the
following evening the growing crescent will appear to the left of
the planet. The Moon then takes on Spica and Saturn, shining
to the west of the star the evening of Sunday the 11th and then
fitting neatly between Spica and the ringed planet the following
evening. Later in the week, watch as the waxing gibbous passes
through northern Scorpius, seen to
the north of Antares the night of
Thursday the 15th.
For all the time it has been visible, Venus still sets pretty
early, a bit before the end of evening twilight. As augured above,
Saturn is slowly moving in on it. Now well into the southwest by
the time the sky gets dark, Saturn is down just after 11 PM
Daylight Time, giving us less and less time to see it. The morning
sky features larger and brighter Jupiter.
Eminently visible in southern Gemini, Jupiter rises in the northeast around 3 AM well
in advance of twilight. Less than an hour later, much dimmer Mars rises to
the south of Castor and Pollux, giving us a fine chance to
see the two planets close to each other. Not far east of the
Summer Solstice, the planets are about as far north of the celestial equator as they can get.
The big event of the week is the best-known of all meteor showers,
the Perseids
. Appearing to emanate from the constellation Perseus, the debris of comet Swift-Tuttle
(which last passed us in the early 1990s on its 130 year orbit)
give a reliable show from a dark site of perhaps a meteor a minute.
The upside of the shower is that the Moon is well out of the way,
while the downside is that the maximum occurs during the day on
Monday the 12th. The mornings of Monday the 12th and Tuesday the
13th before the onset of twilight will therefore be equally good
for watching (mornings for the shower better then evenings).
The shower can be seen at lesser levels for several days on
either side of the peak.
As the sky darkens, Sagittarius
(nicely defined by the upside-down Little Milk Dipper) is well planted near the southern
meridian. To the west of it shine the
stars of Scorpius, best marked by
the red supergiant Antares, the
stars of Lupus (the Wolf) setting
to the southwest. Then look nearly overhead to see white Vega. About halfway up the sky to the
north (depending on latitude), the
real Little Dipper can be seen
standing on its handle, which ends at the North Star, Polaris.
