Skylights featured on Astronomy Picture of the Day

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Sea and sky

Photo of the Week. What lies beyond...?.

Astronomy news for the week starting Friday, July 5, 2013.

We begin the week with the Moon in its waning crescent phase as it heads towards new Moon the night of Sunday, July 7. Your last glimpse of it will be as an ultrathin crescent in the eastern dawn sky the morning of Saturday the 6th. With binoculars you might spot Mars up and to the left of the crescent and brighter Jupiter down and to the left. We then switch around to see the waxing crescent in the west beginning in twilight the evening of Wednesday the 10th, with bright Venus up and to the right of it. By the next evening the growing crescent will be well to the left of the planet at about the same angle above the horizon.

We also begin the week, the fifth of July, with the Earth at its orbital aphelion, where it is farthest from the Sun, 1.7 percent farther than average. Just a day later, on Saturday, July 6, the Moon passes its apogee, where it is farthest from Earth, some 5.5 percent farther than average. The effect is to diminish the range of coastal tides (which are maximized each month at new and full Moons when the Earth, Moon, and Sun are aligned) to about 25 percent below the average.

While Venus is slowly entering the scene (though still difficult to see), Mercury is gone, as the planet passes through inferior conjunction with the Sun (on the near side of it) on Tuesday the 9th. With four of the ancient planets either in twilight or gone altogether, we are left with lonely Saturn. Well into southwestern skies by the time darkness descends and still a dozen degrees or so east of Spica in Virgo (making for quick identification), even this planet does not hold on for long. After setting around 1:30 AM Daylight Time, the sky is oddly devoid of bright ancient planets for well over two hours until Mars and Jupiter rather invisibly ascend in dawn's light. Since last February, Saturn has been in retrograde motion, creeping slowly westerly against the background stars, approaching Spica. On Tuesday the 9th, the ringed planet stops retrograding and resumes its normal easterly motion as it heads back toward Libra, leaving Spica even further behind to the west.

By midnight, two of the most prominent constellations are split by the southern meridian, Sagittarius to the left, Scorpius to the right, the Milky Way cascading down through them. Directly above Scorpius, find the giant pentagon that makes Ophiuchus, with Serpens wrapped around him, and farther north still Hercules, which lies to the west of the bright star Vega of Lyra.
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