AstroCal – August 2021

 

     August means cooler evenings, a noticeable shortening of the daylight hours as we reach the midpoint between the Summer Solstice and Fall Equinox, and (hopefully) clear skies to provide some  prime sky watching conditions.  It is also the time of year when people eagerly anticipate the annual Perseid meteor shower.  The peak of this year’s Persied’s will fall in the pre-dawn hours of August 12, but increased meteor activity usually occurs several days before and after the peak.  The New Moon will take place just four days earlier on August 8, so the very young Crescent Moon will not hamper viewing.

     The Persied’s are known to some Catholics as the “tears of Saint Lawrence”or the ‘coals of Saint Lawrence” to mark that saint’s martyrdom in 258 AD.  In 1835, Adolphe Quetelet noted the shower emanated from the constellation Perseus.  Italian astronomer Giovanni Schiaparelli discovered the link between meteor showers and comets in 1866 from observations of comet Swift-Tuttle’s perihelion pass (closest approach to the Sun) in 1862.  Though it takes 133 years for Swift-Tuttle to complete one orbit of the Sun, a cloud of particles ejected by the comet each time it nears the Sun remains.  Typically, a comet grows a tail as the Sun energizes the comet’s coma or core and meteor showers are created when the Earth passes through this stream of cometary debris.  Swift-Tuttle’s last perihelion approach was in 1992 but the stream of debris remains even as the comet is outward bound and will not make the next close approach to the Sun until 2125.

     The radiant, or the point from which meteors appear to originate, for the Perseids only appears to be in the vicinity of the constellation.  The particles that we observe as streaks of light are heated by atmospheric friction and they burn up about 60 miles above the Earth’s surface.  The stars in this shower’s namesake constellation, Perseus, the Hero, are actually located light-years away so the meteors only appear to be ‘coming from the constellation.”.

Perseus can be located in the Northeast after midnight, just below the ‘3 shaped’ Cassiopeia.

     Having previously mentioned the New and Crescent phases, other notable Lunar dates for August will include the First Quarter (Aug 15), the Full Moon (Aug 22), and the Last Quarter (Aug 30).  The August Full Moon will be a Blue Moon, but not because it will actually appear blue in color.  We have previously defined a ‘blue moon’ as the second full moon taking place in one calendar month.  The August Blue Moon meets a second definition:  the third of four full moons occurring in a single season.  A third description to the term could be made by including the song Blue Moon.  Most people probably first heard the song as recorded by The Marcels, but the list of artists who have recorded the number would stretch longer than this whole AstroCal.  Everybody from Frank Sinatra to The Beatles have done versions of Blue Moon, so I was curious if it was written about the astronomical blue moon.  The original tune and lyrics were written by Rogers and Hart for Jean Harlow to sing in an MGM movie in 1933 (originally titled Prayer).  New lyrics were written and it served as the title song for the 1934 film Manhattan Melodrama.

MGM’s Jack Robbins convinced a reluctant Hart to pen one more set of lyrics because he felt it had commercial appeal (with more romantic lyrics).  As a result, the first recorded version of Blue Moon (the one that lives on today) first appeared in the Variety Top Ten in January of 1935 where it stayed for 18 weeks..

     Planetary observations for August haven’t changed much since July.  Mars will be a challenge as it sets in the west only an hour after sunset early in the month.  Look for it just below and to the left of the young Crescent Moon on August 9.  Jupiter rises in the ESE an hour after sunset while Saturn will be located slightly above and to the right of its fellow gas giant.  Saturn will be at opposition on Aug 2 with a magnitude of +0.2  while Jupiter reaches opposition on Aug 18.  Both Jupiter and Saturn will still be visible in the SW before dawn.  Mercury will appear near Mars on Aug 18 and replace it in the western sky as the Red Planet continues to drop from view.  Venus will be the easiest of the four evening planets to view shining bright at -4.5 magnitude.

     The viewing challenge for the month is the variable star Mira.  Look for it in the pre-dawn sky in the constellation of Cetus the Whale.  Mira dims and brightens on a 11-month cycle and should be visible for a couple of months to the unaided eye shining at magnitude +3.0.

     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 the their website at http://abramsplanetarium.org/skycalendar/ or on Twitter at http://twitter.com/AbramsSkyNotes.  Yearly subscriptions cost $12 and can be started anytime.

Top Piece Video:  I am told by a knowledgeable source that listening to continuous playbacks of Blue Moon can lead to insanity.  Never-the-less, here are the above mentioned Marcels.