On the night of September 5/6, the gibbous moon appears to guide the bright planet Mars.

Update: Photo from September 5, 2020.

by Jeffrey L. Hunt

On the night of September 5 – September 6, the gibbous moon appears near Mars, a very bright planet in the southern sky before sunrise.  Currently, Mars is the fourth brightest “star” in the sky.  Only, the moon, Venus, and Jupiter are brighter.

As Earth approaches Mars, the Red Planet brightens – during the next six weeks – although it is not much larger in appearance to the human eye.  Even with a closest approach pending, the planet only resembles an overly bright star. While it can double in its apparent size through a telescope, the increase is imperceptible to the human eye (unlike what is shown in the social media memes.)

On the evening of September 5 and morning of September 6, the bright gibbous moon is near the Red Planet.  Here’s what to look for on the night before and after the grouping:

• September 5: One hour before sunrise, the bright gibbous moon is over 40° up in the southwest.  The moon is over 91% illuminated.  Mars is 9.6° to the upper left of the lunar orb.  The separation is about the distance across your fist at arm’s length.  In the evening, about three hours after sunset (10:15 p.m. CDT, in Chicago), the moon – about 86% illuminated – is to the lower right of Mars, about 0.8° away.  That’s about the distance across two fingertips at arm’s length. Find them in the east. On these evenings find bright Jupiter and Saturn – to Jupiter’s upper left – in the south-southwest sky.

Update: Photo from September 6, 2020.

• September 6: One hour before sunrise, the moon is over halfway up in the southwest.  Mars is 2.3° to the lower right of the lunar orb.  Three hours after sunset in the eastern sky, bright Mars is over 11° to the upper right of the moon that is 79% illuminated.  The moon is near the eastern horizon. 
• September 7: One hour before sunrise, the bright moon – 77% illuminated – is less than 60° in altitude in the south-southwest.  Mars is about 15° to the lower right of the moon. 

Each night, the moon is farther east of Mars and it begins to approach Venus in the east in the morning sky.  Look for the crescent moon and Venus on September 14.

Here is a daily summary about the planets during September.