Tuesday, August 14, 2012

Arcturus above Saturn/Mars/Spica grouping

Event Date: August 22nd
Time: 8:30 PM

Brief

   Yesterday when the Moon was grouped with Mars, Saturn and Spica, I posed the question about a bright star seen above it in the sky a little further north; a line extending from it through Saturn lead almost the Moon's position.  Although the Moon has moved east of the grouping since then, we can still see the other three as a near-isosceles triangle; Spica and Saturn are a little closer together than Mars is with the ringed planet. 
   Here is Arcturus, seen high above Mars, Saturn and Spica.  The Moon, which is quickly "fattening" as a crescent, is seen to the small triangle's left.  Mars is the closest to the Moon, with Spica as the furthest (angularly).
click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   Arcturus sets after the trio by about two hours, after being high in the sky during most daylight hours.  The star rose shortly after 10 AM, and while still far enough apart from the south-moving Sun, can be seen during daylight hours through a powerful telescope and the clearest of skies.  At magnitude -0.1, it transits high in the sky during the early evening.  Try to find it at about 7:30 PM local time with smaller telescopes if you know where to look; this is the time when the limiting magnitude of the sky starts to gradually decrease in value, letting us see the brightest of stars in the sky a little more easily.
   Getting back to the Mars/Saturn/Spica grouping, they are still able to fit in a binocular field of 6º, yet barely.  As mentioned yesterday, try a field of 7 or 8º to get them all in more easily.

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