May 22, 2023

AstroCal – June 2023


     We begin this month with a rather unique observing challenge known as ‘opposing crescent Moons’.  This happens when the last faint crescent Moon of the latest cycle of phases is seen one day and the first new crescent Moon of the next cycle is seen the next day.  On December 31, 2013 and January 1, 2014, Alex Seidier was able to see this phenomenon with the two sightings taking place just 34 hours and 37 minutes apart.  In that Seidier’s observation was optically aided, we do not think anyone will beat his record this time around, but if one nails these two crescent Moon sightings, it would certainly be a personal viewing event worth remembering.

     The more difficult of the two observations will be just before dawn on June 17.  Look ENE for the old crescent Moon just to the lower left of Mercury – it will be very near the horizon.  Even if you miss this sighting, look just below Pollux & Castor (in Gemini – the Twins) in the twilight skies on June 18 (WNW – again, very close to the horizon).  Happy hunting.  If you do see the New Crescent Moon on June 18, it will be less than 24 hours into the new Lunar Cycle.

     Other Lunar events for June will include the Full Moon (June 3), the Last Quarter Moon (June 10), the New Moon (June 18), and the First Quarter Moon (June 26).  Let us also not forget to mark the Summer Solstice at 10:58 a.m. EDT June 21 when the Sun will reach its highest point in our Southern Sky.  The Great Lakes Region will still be a few weeks away from the warmest temperatures of the year even though June 21 still marks the official beginning of Summer and our longest period of daylight.

     Morning planets in June include the aforementioned Mercury.  This is not a great apparition for viewing Mercury for northerners as it will only climb about 2 degrees above the horizon early in the month.  Shining at -2.2 in Aries – the Ram, Jupiter will be the standout object in the dawn sky.  It will start low in the East and climb higher as the month progresses.  Saturn will appear in Aquarius – the Waterbearer – look to the southeast early in the month and watch it climb higher toward the south later in the month.  Saturn’s magnitude will be +0.9 to +0.7 and The Ringed Planet will begin retrograde motion (appearing to move backwards through the fixed stars) on June 17.  The Rings of Saturn will be tipped 7.3 degrees from edge-on, the least tilt we will see for this year.

     In the west, Venus will start the month 5 degrees left of Pollux one hour after sunset.  Just left and slightly above Venus, (almost directly west) will be Mars.  Venus will continue to close the gap between the two planets throughout the month/

     Venus reaches its greatest elongation (the furthest distance it will appear from the edge of the Sun) on June 3rd and will brighten in magnitude from -4-4 to -4.7 as it moves closer to us.  On June 1, it will be 67.8 million miles from Earth and close to 46.3 million miles by June 30.  The disk of the planet will be nearly 23 arcseconds across and 51 percent illuminated.  The crescent will be large enough to detect even with binoculars if observed in daylight or bright twilight when the contrast between the light and dark sides is the greatest.  After that, the planet will be too bright against the dark sky to see the crescent shape.   

     Our June Historical Astronomical event takes us back to 1978.  James Christy suggested to his supervisor at the US Naval Observatory that they should request photos of Pluto to be taken with the 60-inch reflector telescope at Flagstaff, Arizona.  The telescope was engaged in taking photos of Neptune and Uranus at the time and Christy felt it would be a good opportunity to get some photos of Pluto as well.

     When the Pluto photos arrived on June 21, 1978, Christy sat down with them to take his mind of his family’s impending move from their apartment to a new house.  Using a Starscan imaging computer, he began to examine the photographic plates.  The plates had been labeled as ‘defective’ but he still took a look at them, soon spying a bulge along Pluto’s limb.  Upon further investigation, he was convinced he was seeing an undiscovered moon.  When he reported the findings to his supervisor, he responded, “Jim, you’re crazy!”  By the next Friday, June 23, Christy had found confirmation of his newly discovered moon on other photographic plates that had been taken in June of 1970.  Mathematical calculations matched the movements of Pluto with an orbiting moon further cementing Christy’s notion that he had discovered a new moon.

     Christy wanted to name the new object ‘Char’ in honor of his wife and added ‘on’ so it would conform to other scientific terms such as ‘electron’ or ‘proton’.  Further investigation of the name proved ‘Charon’ was the Green name for the ferryman who conveyed the dead across the River Styx, a good fit for the companion of Pluto, the Roman god of the underworld.  

  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:  Okay, they are miming and using dueling keyboards . . .  but we thought we would get a jump on the season here with the Loving Spoonful . . .