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!


Photo of the Week. Spring flowers, blue sky.

Astronomy news for the two weeks starting Friday, March 13, 2015.

The next skylights will appear March, 27, 2015.

Skylights' current two-week period is the result of travel and medical issues. I hope to go back to weekly reports. Thanks for your patience.

The fortnight is bracketed by the lunar quarters, third quarter passed on Friday, March 13, first quarter on Friday, March 27. In between, the Moon first diminishes in the waning crescent phase, then passes new on Friday the 20th, after which it grows in the evening through the waxing crescent, all giving us a fine show. At its new phase, the Moon usually passes above or below the Sun, compliments of the five degree orbital tilt to the ecliptic (the path of the Sun against the background stars). Not this time. Instead, it glides right across the solar disk to produce a total eclipse. Unfortunately, totality avoids significant land masses, crossing from the North Atlantic into the Arctic. The partial eclipse also avoids North America, though it will be widely seen in Europe and Asia. The Moon goes through perigee, where it is closest to Earth, on Thursday the 19th. Proximity to perigee is one of the requirements for a total eclipse. Were the Moon near apogee (farthest), it would appear too small in angular extent to cover to solar disk, resulting in an annular eclipse.

Third quarter will appear well to the left of Saturn. Look for the reddish star Antares of Scorpius down and to the right of the Moon. A far better show will take place on the evening of Sunday the 22nd, when the waxing crescent will make a beautiful pairing with brilliant Venus, the planet to the right. The night before, the Moon will be paired with Mars, the red planet still setting around 8 PM with the end of twilight catching up with it.

Jupiter still sits near the Leo-Cancer border to the west of Regulus. Watch as it crosses the meridian to the south in mid evening. Jupiter has been in retrograde (backward, east to west) movement against the stars since late last year. And now it is Saturn's turn, as it enters retro on Saturday the 14th, the ringed planet rising shortly after midnight.

The really BIG event is the passage of the Sun across the Vernal Equinox in Pisces at 5:45 PM Central Daylight Time on Friday the 20th, which marks the beginning of northern hemisphere spring, the event oddly taking place at almost the same time as the eclipse. With the Sun on the celestial equator, it will technically rise due east, set due west, be up for 12 hours and down for 12, rise at the north pole and set at the south pole. In reality, refraction by the Earth's atmosphere and that sunrise and sunset are counted from the top of the Sun, not the center, extend daylight slightly beyond 12 hours and cause the Sun to rise at the north pole a bit in advance of equinox passage, etc.

As we pass into spring, the winter constellations (Taurus, Auriga, Orion, and the rest) slowly exit to the west, though there is still plenty of time to see them. By 9 PM, the eastern fringe of them, marked by Gemini (with Castor and Pollux) and Canis Minor (with Procyon), lounge near the celestial meridian. Later in the evening, follow the curve of the handle of the Big Dipper to the south to find orange Arcturus near the southern end of Bootes (the Herdsman). To the east of Bootes is the graceful curve of stars that makes Corona Borealis, the Northern Crown.

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