Skywatch Line for Friday, June 7 through Sunday, June 9, 2019

This is Dudley Observatory’s Skywatch Line for Friday, June 7 through Sunday, June 9, written by Sam Salem.

On Friday, Sun rises at 5:18am and sets at 8:32pm; the waxing crescent Moon rises at 9:33am. On Saturday and Sunday nights use the Moon to find Regulus, the brightest star in the constellation Leo, the Lion. This blue-white star is of 1st-magnitude brightness and is the 21st brightest star. The Moon is close to Regulus for only a few days each month. When the Moon is no longer there to guide you, use the Big Dipper to guide to this star. The two bowl stars on the handle side of the Big Dipper point to Regulus.

Only two of the five naked-eye planets are in good position for telescopic inspection. The other three hug the horizon. Low in the west at dusk you’ll find Mercury and Mars. Mercury, at magnitude –0.6, rises six degrees above the west-northwest horizon 45 minutes after sundown. Its sets a few minutes after 10pm. Mercury is starting its second evening apparition of this year. Mars glows at magnitude 1.8 as it slowly makes its way eastward through Gemini. Mars sets roughly two hours after the Sun. Jupiter reaches opposition on Monday. Which means it’s up all night. This weekend offers a great opportunity to enjoy Jupiter at its best. Jupiter, at magnitude –2.6 at the eastern leg of constellation Ophiuchus, presents the maximum amount of detail when its altitude is better than at least 15 degrees. Your best observing window runs from roughly 10:30 to 3:30am. Saturn rises shortly after 10:30pm. The best time to view Saturn and its magnificent rings in a scope is a little before 3:30pm, when the planet is highest. Saturn, at magnitude 0.2, is easy to identify as the brightest dot of light in eastern constellation Sagittarius. Venus, at magnitude –3.8, rises less than an hour before the Sun and hovers barely above the east-northeast horizon in bright twilight.

Globular cluster M5, in the constellation Serpens Caput, is one deep-sky object that is currently well positioned. M5 is the westernmost point in an equilateral triangle that also includes the stars Alpha (α) and Mu (μ) Serpentis. M5 holds the distinction of being the brightest globular cluster in the northern sky. The Serpens cluster is an easy binocular target, though the low magnification, typical of binoculars, makes all but a few globulars appear nearly stellar. M5 lies next to a similarly bright star, 5th-magnitude 5 Serpentis. In a telescope M5 is a splendid sight, and the greater the aperture, the better the view. The cluster’s luminous, tightly packed central knot is enveloped in a spherical swarm of faint stars. Some amateur observers consider M5 the finest globular cluster north of the celestial equator for small telescopes, even better than the celebrated M13, the Great Hercules cluster.

This Friday marks the 91st birthday of Bernard Flood Burke, the American astronomer who co-discovered that planet Jupiter emits radio waves. In 1955, Burke and Kenneth L. Franklin, at the Carnegie Institution in Washington, were scanning the sky for radio waves from galaxies. By chance, they found a radio signal that resembled short bursts of static, similar to interference by lightning on home radios. After weeks of study, finding the signals were periodic, four minutes earlier each day, they pinpointed Jupiter as the source. This was the first time radio sounds from a planet in our solar system been detected.

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