Astronomy news for the two weeks starting Friday, August 12,
2016.
The next skylights will appear August 26.
And a remarkable fortnight it is. As we open, we are just coming off the
Perseid meteor shower, and we
should still get a few the morning of Saturday, August 13. And it still
won't be much bothered by the Moon, which is only in its early waxing gibbous phase and sets well before
dawn begins to light the sky. The Moon finally passes full ("the green corn moon, the "grain
moon") the morning of Thursday the 18th, bright and high in the western
sky. The Moon then quickly transitions to its waning gibbous phase, which ends at last quarter the night of Wednesday the
24th, followed by a bit of the waning
crescent.
The morning of Thursday the 25th, the Moon will rise just barely west of
bright Aldebaran. For the eastern
and southern US, the Moon will occult or cover the star, though (except
in Texas, where it will be dark) in twilight or, as in the northeast,
after sunrise. In addition the full Moon will undergo a brief eclipse. But don't
get too excited about it as the Moon only barely clips the Earth's
penumbral (partial) shadow, the "event" quite undetectable.
It's far better to watch Saturn, which
are beautifully visible in the southwest in and after evening twilight.
Saturn, north of Antares (the luminary of Scorpius) and to the east of Mars, ends its
retrograde (easterly) motion against the stars on Saturday the 13th,
and is so far away that it hardly seems to move at all, while Mars is so
close to us that its orbital motion to the east can be witnessed near
night-to-night as it rapidly overtakes the ringed planet. On Tuesday the
23rd, Mars will pass just 1.8 degrees north of Antares and then on
Thursday the 25th four degrees south of Saturn. We then see a remarkable
stack of celestial bodies with Saturn on top, Mars in the middle, and
Antares on the bottom. It's a good time to compare colors. Saturn is a
yellow-white, while Mars and Antares are reddish, the star's very name,
meaning "rival of Mars," Ares the Greek version of the god of war. While
their colors are similar, Antares, a huge supergiant, is clearly the
redder of the two. Look early, as they all set around midnight daylight
time. `
Stretching our fortnight a bit, a day after Mars passes Saturn, on
Friday the 26th,
Mercury (practically invisible) goes 5 degrees south of Venus, and then on the next day, Venus goes just
0.07 degrees north of Jupiter, the events very
difficult to see because of bright western twilight. Want more? Mercury
passes greatest eastern elongation on Tuesday the 16th, Neptune is
occulted by the Moon on Friday the 19th (though in daylight and only in
the far north), and the Moon is at perigee,
closest to Earth, on Sunday the 21st.
For a bit of relief from all this activity we turn to the stars. In
early evening, white Vega, the second
brightest star in the northern celestial
hemisphere, lies nearly overhead, while orange Arcturus falls to the southwest,
sandwiched between faint Coma Berenices
with its sprawling cluster and the head
of Serpens, the Serpent, which wraps
itself around Ophiuchus. Well south
of Arcturus, blue-white Spica sparkles
in Virgo.
