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. Quiet sunrise.

Astronomy news for the two weeks starting Friday, April 22, 2016.

The next skylights will appear May 6.

The Moon fades away. Having gone through full the night of Thursday, April 21, it spends the first week of our period in the waning gibbous phase. Passing third quarter the night of Friday the 29th, it spends the second week as a waning crescent, the phase terminated at new Moon on Friday, May 6. On the night of Saturday the 23rd the Moon will appear west of Mars and Saturn, while the following night it will fall west Saturn and north of both Mars and the red supergiant Antares of Scorpius, the four making a ragged box. By the night of Monday the 25th, the Moon will have moved to the left of the planets, the three now making a pretty line.

The lunar orbit rather oddly tracks the phases. Thirteen hours before full Moon last Thursday the 21st the Moon stood at its tides at the coasts (a change of 11 percent in distance making the ocean tides nearly some 35 percent larger, high tide to low).

Jupiter dominates the evening scene, crossing the meridian to the south about as full darkness descends. Half an hour later Mars comes up, then, after another half-hour, Saturn rises, the two nicely gracing the southeastern sky as presaged above and making a triangle with Antares below. After the Moon is out of the way, it's easier to see the color similarity between Mars and its namesake Antares and the contrast with yellowish Saturn, Mars's redness basically coming from iron oxide in the "soil," actually the "regolith" as Martian surface material carries no organic compounds, the by-products of life. Or at least as we have so far found. In addition to these bright planets we can count Mercury, which early in the fortnight is making a good appearance (about as good as it gets) in western evening twilight. But look early, because it's quickly gone.

Keep your eye out for the Eta Aquarid meteors the mornings of Thursday and Friday, May 5 and 6. With the Moon out of the way, the debris of Halley's Comet may make a decent showing before dawn.

As spring advances, Orion and his gang flee to the west. Early on though, we can still admire the Hunter and his two dogs. The three constellations carry five first magnitude stars: Betelgeuse and Rigel in Orion; Sirius and Adhara in Canis Major (to the south-southeast of Orion, Adhara below Sirius); and to the east of Betelgeuse, Procyon in Canis Minor. Betelgeuse, Sirius, and Procyon make their own group as the Winter Triangle. The trio more or less encloses a faint modern constellation, Monoceros, the Unicorn. Above the Winter Triangle are the stars of Gemini with first magnitude Pollux and the brightest of second- magnitude, Castor.
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