Saturn, Mars, Spica, and waning Moon grouped

Event Date: August 21st
Time: 8:30 PM


Brief

   Back on the 17th, I mentioned revisiting the Mars/Saturn/Spica trio; as a teaser, that they would have company.  That is correct, and that company is the waxing crescent Moon: 23% illuminated.  The four make a lopsided diamond shape, which gives it a perhaps "symbolic" appearance, depending how one thinks of it.  Even more impressive, as was the case yesterday, the triangle of planets and Spica is near-isosceles in shape, with Saturn as the apex.  More about that and separation values are in the detailed section.  First, I will show the quartet of Spica and solar system bodies unlabeled during the first minutes of nautical twilight.  Spica is closest the the Moon's lit portion, Mars closer to its darker portion.  What is that star in line with Spica and the Moon higher up??  Find out tomorrow, yet try guessing first, based on its position at this time of evening and year.

Detailed

   Both Mars and Spica are 4.6º from Saturn, with the difference of separation just arc-seconds from being isosceles.  As the evening goes on, Mars moves slightly further from both, although not noticeably with the eyes.  Using binoculars, they all fit in a 5º field, although using a field of 7 or 8º will be easier to view all three center-fielded.  Also, this is the way to view the Moon with them.  The second image shows all four in the field, shown here. 

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

   A few numbered stars from the constellation of Virgo (unlabeled) show in the field, all about the same magnitude.  One or two dimmer stars are also just starting to become visible at this hour with this field.  As the sky grows darker, more stars come visible quickly.  Since when looking at stars and planets in Virgo means looking nearly perpendicular to our galactic plane, it means that we don't have alot of deep sky targets easily visible to look at; mainly distant galaxies which are washed out by twilight and obstructed by atmospheric pollution.  When we start to get Virgo high in the morning sky late this fall, we will have a better chance to see some of those galaxies more easily with powerful telescopes.