Skywatch Line for Friday, June 12, through Sunday, June 14, 2020

This is Dudley Observatory’s Skywatch Line for Friday, June 12, through Sunday, June 14, written by Sam Salem.

On Friday, Sun rises at 5:16am and sets at 8:34pm; Moon rises at 1:13am and sets at 12:05pm. Last quarter Moon occurs at 2:24am on Saturday. At last quarter, the Moon rises around midnight (standard time) and remains visible in the southern sky during morning daylight.

Earliest sunrise of the year happens these days. That’s despite of the fact that the summer solstice, and the year’s longest day, are still about a week away. The exact date of earliest sunrise, and latest sunset, varies with latitude. In our area, Sun rises at 5:16am since Thursday. This is the earliest sunrise time of the year. Sun will rise a minute later starting next Friday.

Look for the last quarter Moon passing Mars and Neptune this Weekend. In the southeastern pre-dawn sky, Mars will sit near, dim, and blue-tinted Neptune. At closest approach, Neptune will sit 1.5 degrees to the north of Mars, allowing both planets to appear together in the field of view of amateur telescopes. Magnitude -0.19 Mars will shine nearly 1700 times brighter than magnitude 7.9 Neptune.

The waning half-illuminated Moon will pass, four finger widths, to the lower left of Mars in the southeastern sky in the hours before dawn on Saturday. The duo will fit into the field of view of binoculars. Mars is brightening and enlarging. In a telescope it’s now 10 arc-seconds wide, a little gibbous disk 85% sunlit. Mars, in dim Aquarius, is 40° to 45° left of Saturn, as dawn begins. Saturn glows pale yellow, 5 degrees to Jupiter’s left.

Mercury remains under Pollux and Castor in evening twilight. It has now faded to magnitude 1.3. That’s less than half as bright as Procyon, mag 0.4. Mercury will appear even fainter considering the greater atmospheric extinction at its lower altitude and the brighter sky there too. Binoculars may help.

In the evening sky this weekend, the orbital motion of the main belt asteroid designated (2) Pallas will take it 1.5 finger widths to the upper left of the Coathangar Cluster in the constellation of Vulpecula. Also considered an asterism, the Coathangar is an easy target for binoculars, located midway between the bright stars Vega and Altair. The magnitude 8.94 asteroid and most of the cluster’s stars will appear together in the field of view of telescopes at low magnification.

The big Summer Triangle shines high in the east after dark. As dusk deepens into night, look eastward for this great star pattern, an asterism made of three bright stars in three different constellations. Look for the brightest star in eastern sky, Vega, the brightest star in the constellation Lyra the Harp. Look to the lower left of Vega for another bright star Deneb, the brightest in the constellation Cygnus the Swan and the third brightest in the Summer Triangle. An outstretched hand at arm’s length approximates the distance from Vega to Deneb. Look to the lower right of Vega to locate the Summer Triangle’s second brightest star, Altair, the brightest star in the constellation Aquila the Eagle. A ruler held at arm’s length fills the gap between these two stars. Under dark, moonless, sky, the Milky Way runs through the Triangle’s lower part from side to side.

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