Skylights featured on Astronomy Picture of the Day

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Skylights featured nine times on Earth Science Picture of the Day: 1 2 3 4 5 6 7 8 9 -- Full List Restored!

Hazy setting Sun

Photo of the Week.. The Sun sets peacefully through horizon haze.

Astronomy news for the two weeks starting Friday, June 16.

The next Skylights will appear July 7, 2017.

The last fortnight was the "bright run" with the Moon between first and third quarters lighting up the sky and hiding the stars. Though the full Moon is only a half-millionth as bright as the Sun, that is plenty enough light to make a lot of observing impossible. This fortnight, however, we encounter the flipside, the "dark run" between third quarter on Saturday the 17th near dawn and first quarter the morning of Friday, June 30, these two phases now centered on new Moon, which is passed on Friday the 23rd. In between third quarter and new, on Tuesday the 20th, the waning crescent Moon will make a fine sight with Venus to the left, while by the next morning the Moon will have slipped another 13 degrees along its path and will be down and to the left of the brilliant planet, which rises just as the first glimmer of dawn begins to light the eastern sky. Shifting your gaze to the west to watch the waxing crescent will yield a memorable sight when it is seen just south of Regulus in Leo. The Moon passesperigee, where it is closest to the Earth in its eccentric orbit, on Tuesday the 27.

Jupiter, the brightest body in the evening sky (the planet in Virgo northwest of Spica), sets about an hour after Saturn rises in the southeast between Sagittarius and Scorpius. After another hour and a half, Venus rises, its luster putting all the other planets to shame. Going deeper into the Planetary System, Mercury goes through superior conjunction with the Sun (on the other side of it)on Wednesday the 21st.

The big event, though, involves Earth, when at 11:24 PM on Tuesday the 20th (11:24 AM EDT Wednesday the 21st), the Sun passes the Summer Solstice at the most northerly part of the ecliptic, 23.4 degrees north of the equator. On this longest day (and shortest night), the Sun will rise as far northeast (and set as far northwest) as possible, and pass overhead at the Tropic of Cancer (thus defining the Tropic's latitude). North of the Tropic, the Sun will also cross the meridian as far north as possible, giving us the maximum heating rate and, of course, the first day of astronomical Summer. Traditionally the Solstice lies in the constellation Gemini, but around 1930, the 26,000 wobble (precession) of the Earth's axis brought it across the border with Taurus established in 1930.

This time of year brings us a lovely parade of constellations high across the sky, beginning with kite-shaped Bootes (the Bear Driver) with bright Arcturus, the semi-circle of Corona Borealis (the Northern Crown), Hercules, Lyra (the Harp) with Vega, and finally Cygnus (the Swan) with Deneb. The constellations of autumn then begin to appear on the scene.
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