January 24, 2023

AstroCal – February 2023


     Hold the phone!  February begins as January ended with the exciting opportunity to see a deep space comet that last passed our neighborhood some 50,000 years ago.  There are already copious numbers of photos plastered all over the internet of what is being called ‘The Green Comet’ due to its greenish hue.  Comet C/2022 E3 (Z.T.F.) should be visible to anyone with a clear view of the North Star with a little patience.  Making its closest approach to Earth on February 2, 2023, the comet comes within 26.4 million miles of our planet when it will still be 110 times the distance between us and the Moon.  It will be faintly visible to the naked eye so binoculars may help.  Its maximum magnitude is predicted to be around 5.4 – not spectacular, but still worth the time to look for.  One does not get to see many comets in a lifetime. 

      The comet was first spotted by astronomers on Palomar Mountain, California in March of 2022 with a telescope at the Zwicky Transient Facility, thus the origin of the name.  As C/2022 E3 (Z.T.F.) nears the Sun, ultraviolet radiation is being absorbed by molecules in its icy coma (or head).  The molecules in question are diatomic carbon (two carbon atoms fused together) and this reaction emits green light.  Since it made its closest approach to the Sun on January 12, the comet has been slowly moving through the constellation of Draco the Dragon.  If you can use the Pointer Stars at the ‘cup end’ of the Big Dipper to trace a line to the North Star located at the end of the handle of the Little Dipper, then you have a chance to spot it in early February.  To locate it, visually trace the line between the Big and Little Dippers until you see a greenish smudge – that will be the comet.  Unlike the quick steak of light one sees with a meteor, comets move much slower and are thus visible over many nights.

     Dark skies would aid anyone trying to see Comet c/2023 E3 but the Full Moon will take place on February 5 – not exactly great timing.  The Last Quarter Moon (Feb 13), New Moon (Feb 20) and the First Quarter Moon (Feb 27) will round out the change from the old to the new Lunar cycle this month.  On Feb 22, the Young Crescent Moon will have a very close encounter with Jupiter that can be observed in the WSW sky one hour after sunset.

     Speaking of Jupiter, the period from February 19 to March 11 will see a Venus-Jupiter pairing in the western sky that will make for some entertaining sky watching.  They will begin and end their dance about 10 degrees apart (the width of your closed fist held at arm’s length) on Feb 19 and March 11.  On Feb 24 and March 6, they will be closer at 5 degrees (the width of three fingers held in a Boy Scout salute).  If you can see where this is heading, the Ju-Ve pairing will be separated by a mere 0.5 degrees (half the width of your pinky finger nail) when viewed in the WSW sky one hour after sunset on March 1.  Saturn will also be located in the western sky but it is very close to the horizon at sunset and will drop from sight entirely by mid-month.

    Other random notes about February sky events:  Mercury will be visible just above the eastern horizon (and just left of the Tea Pot Asterism found in Sagittarius, the Archer) in the hour just before sunrise.  It would be a good observing challenge because A) you need to be up at sunrise and B) it will be very, very close to the eastern horizon.  On Monday Feb 27, look for Mars just to the left of the First Quarter Moon.  It should also be noted that the Moon will reach apogee (its farthest distance from the Earth at 252,572 miles)  at 4 a.m. EST on Feb 4.  We recently discussed the phenomenon called Zodiacal Light.  This is a faint glow of diffuse sunlight scattered by interplanetary dust that faintly illuminates the night sky.  When it happens before sunrise, it is sometimes called ‘false dawn’.  During the period between Feb 8 and Feb 20,  the Moonless skies will provide an excellent opportunity to try and observe Zodiacal Light at the end of evening twilight.

     Coming up in the near future will be a continuing series of the monthly conjunctions of the Moon and Venus with the best one occurring on June 21.  Venus will also be ‘chasing’ Mars through the Zodiacal Constellations before it finally gives up the chase and the distance between them again begins to increase.  As always, more information on these and other sky observing events can be found on the Sky Callendar Extra Content Page at .

   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:  There are not that many songs about comets – but Journey has one – this is Kohouteck performed live in Osaka in 1980