The Sky This Month – May 2013

Annular_EclipseSaturn remains the finest bright object in the heavens this month.  The ringed planet lies well above the southeastern horizon in the late evening hours.  With a tilt of some 19° from edge on, the rings of Saturn are primed for inspection with a small telescope.   You’ll also find a great photo-op as three more planets form a tight triangle in the western sky after sunset later this month.  And early May holds the best meteor shower of the year for southern-hemisphere stargazers.  Here’s what to see in the night sky this month…

2 May.  Last Quarter Moon, 11:14 UT

4-5 May.  The eta Aquariid meteor shower peaks over the night of May 4 and before dawn on May 5.  This is usually the best meteor shower of the year for southern-hemisphere observers.  At its peak, you may see 1-2 meteors per minute before dawn, and this year a waning crescent Moon will make for little skyglow.  So it should be a good show.  Meteors can appear anywhere in the sky and trace their path back to a point near the star eta Aquarii just above the eastern horizon. Very few meteors will be visible to observers in the northern hemisphere.

10 May.  New Moon, 00:28 UT

10 May.  An annular eclipse of the Sun is visible across northern Australia and the south Pacific.  In an annular eclipse, the Moon is a little too far away to cover the Sun’s entire face, so a ring of light remains visible around the Moon during the eclipse (see image above).  The path of the eclipse moves west to east across north-central Australia, the southern tip of the Gulf of Carpentaria, and into the Pacific.  The eclipse is partially visible from all of Australia.  It begins at sunrise in western Australia and progresses throughout the day.  NOTE: You will need a solar filter to safely observe this eclipse… at no time is it safe to observe an annular eclipse without a solar filter!!

11-12 May.  A thin crescent Moon shimmers near the planets Jupiter and Venus just after sunset in the west-northwestern sky.  Use binoculars to get the best view.

18 May.  First Quarter Moon, 04:35 UT

22 May.  The Moon lies near the bright star Spica and the planet Saturn in the southeastern sky.  Saturn is splendid in a telescope this month.  The disk spans about 19″ and the rings about 42″ tip-to-tip.  The rings are nicely tilted to our point of view, and this lets us see more detail and structure.  If you have steady sky, look for the Cassini division, a dark gap between the A and B rings.  Use the highest magnification your sky and equipment will allow.  Look also for the orange glow of Titan, Saturn’s largest Moon.  The orange color comes from the selective absorption of light from Titan’s thick atmosphere.

The Moon lies between Saturn and the star Spica on May 22, 2013.  Click to enlarge.

The Moon lies between Saturn and the star Spica on May 22, 2013. Click to enlarge.


24 May.  A nearly full Moon will occult the bright double star β (beta) Scorpii for observers in the eastern and southeastern U.S., Carribean, and northern South America.  This bright and well known double star, also named Acrab, has components of magnitude 2.6 and 4.9 separated by 14″.  The star will pass behind the Moon at approximately 1:30 UT.  All other observers will see the star make a close approach to the Moon on this day.

24-30 May.  Venus, Mercury, and Jupiter join a planetary hoedown above the west-northwestern horizon after sunset.  The planets lie within 5° of each other and make their closest approach on May 26 when they form a small equilateral triangle.


The planets Jupiter, Venus, and Mercury make a small triangle in the WNW sky after sunset on May 26, 2013.

25 May.  Full Moon, 04:25 UT

31 May.  Last Quarter Moon, 18:58 UT