Photo of the Week.. Orion, Sirius, and memories
of winter.
Astronomy news for the week starting Friday, July 27, 2012.
This is the week of the full Moon, which
takes place the night of Wednesday, August 1, with the Moon close
to or actually rising for those in North America. This being
summer with the S
un far to the north of the celestial
equator, the full Moon will appear well to the south of that
circle, among the dim stars of Capricornus to the east of the Winter Solstice in Sagittarius. Prior to its fullness, the Moon will be
fattening in the waxing gibbous phase,
when it rises in the late afternoon or early evening, the last part
of the week seeing a bit of the waning
gibbous. On the night of Monday, July 30, the Moon passes just
south of dim Pluto,
occulting it as seen from Antarctica and far southern South
America. With Pluto 1500 times fainter than the eye can see, the
event is quite unobservable. The day before, the Moon passes perigee, where
it is a bit closer to the Earth than average, the difference in
angular size also not sensible to the eye.
Aside from the glorious summer constellations, evening's
Mars and
Saturn (well into the west as the sky darkens) still draw the
eye, the two planets along with the star Spica (all in Virgo) making a fine triangle with Mars at the western
apex. All three are about the same brightness, Saturn just besting
the others. Relatively nearby, Mars is moving about half a degree
per night to the east against the background stars, fast enough to
notice from night to night. Much more distant Saturn pretty much
just sits there, however, to the north of Spica, letting Mars catch
up to it, the two destined to pass conjunction the night of August
16. Mars now sets at 11 PM Daylight Time, Saturn just half an hour
later.
The morning sky displays an equally fine, if not better, sight. As
Mars approaches Saturn,
Jupiter pulls away now from Venus. The
giant planet rises before 2 AM, an hour before Venus lofts
itself over the horizon. Just to the north of the Hyades in Taurus (hard to see under Moonlight), Jupiter will pass
north of Aldebaran just before
it rises the morning of Friday the 3rd. Jupiter and Venus then
march across the sky to the west until dawn starts to take them
away. Inward of Venus,
Mercury passes inferior conjunction with the Sun on Saturday
the 28th.
The bright Moon wipes out much of the constellation figures, though
the brightest of stars still shine through, notably those of the Summer Triangle, which falls
from overhead to south around midnight. Vega is at the northwestern apex, Deneb at the northeastern, Altair at the southern. Well into
the west, look for Arcturus well
to the north of the Saturn/Spica/Mars configuration.
