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Photo of the Week. Peaceful sunset.

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.
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