April 24, 2023

AstroCal – May 2023


     Greetings sky watchers – let us kick off May with a run down of things to look for in the morning sky.  Saturn can be found in Aquarius, the Water Bearer in the ESE to SE as dawn brightens.  Shining at +0.9 magnitude, a telescopic view would show the rings tipped just 8.0 degrees from edgewise.  On May 13, a 41 percent crescent Moon will appear near Saturn.   It may be possible to see the Rings of Saturn cast a shadow on the WNW limb of the planet with a small telescope on May 28.  

     The recently emerged Jupiter will appear very low north of east (mag -2.1).  On May 17, the 6 percent Moon will occult Jupiter, but one will need to be west of a line stretching from Baton Rouge, LA to Great Falls, MT.  The occultation will occur during daylight hours for those east of this line.  Mercury will be located to the lower left of Jupiter and will become more visible as it brightens from a faint +1.6 (May 17) to +0.4 by the end of the month.  Mercury will reach its greatest elongation (25 degrees west of the Sun) on May 29.

     Turning our attention to the evening sky, Venus will start the month at a brilliant -4.1 magnitude and increase to -4-4 by the end of the month.  To say it will dominate the western sky is an understatement.  Due to its brightness, one should be able to see Venus between 43 and 45 degrees to the upper left of the setting Sun.  As the Sun sets, observers will find this an excellent time to track the changing appearance of our closest neighboring planet as the disk grows from 17 to 23 arcseconds and the phase shrinks from about two thirds illuminated to about one half.

     Mars will also be a faint mag +1.4 located in Gemini, the Twins.  This places it about 26 degrees to the upper left of Venus (remember, extending your thumb and little finger in the traditional surfer’s salute (or perhaps a ‘call me’ gesture) at arm’s length spans about 25 degrees of the sky).  Mars will be shifting about 0.6 degrees against the background stars during May, compared to a 1.0 degree shift for Venus.  Look for the Moon to pass Venus and Mars on May 28 & 29, respectively.  The Red Planet will reach aphelion, or its farthest distance from the Sun, on May 30 putting it at a distance of 1.666 a.u. from the Sun.  An a.u., or astronomical unit, is the distance between the Sun and the Earth.  The a.u. is used as a shorthand method to measure distances in the solar system rather than writing out millions and millions of miles.

     The month will begin with a Full Moon on May 5, followed by the Last Quarter (May 13),

the New Moon (May 19), and the Young Crescent Moon low in the WNW one hour after sunset on May 20.

     This month’s  highlighted historical astrological event took place on May 17, 1902.  Archaeologist Spyridon Stais noticed an inscription on an artifact that had been recovered from an underwater wreck off the coast of Antikythera in the Aegean Sea.  Philologist Albert Rehm studied the object and in 1905, he determined the inscription included the numbers 19, 76, and 223 which helped him uncover exactly what this mysterious object was.  Rehm proposed this artifact, now known as the Antikythera Mechanism, was an astronomical calculator whose origins remain uncertain, but could have been created between 200 BCE and 870 BCE.  The device was not kept intact as it was split into 82 separate pieces while being studied at the Archaeological Museum in Athens, Greece.  It has taken generations of mathematicians, astronomers, and historians to sort out this puzzle, but it is now viewed as the oldest known astronomical mechanical calculator ever discovered.

   Compiled by Ken Raisanen of WOAS-FM – information provided by Abrams Planetarium Sky Calendar, Michigan State University.  More information and subscription information can be found on their website at or on Twitter at  Yearly subscriptions cost $12 and can be started anytime.

Top Piece Video:  As long as Venus is still the star of the show, we will revisit the 1980s and Banarama’s fun take on the Shocking Blue tune.