Constellation Bootes and the star Arcturus

Minnesota Skies: September

Your local guide to observing celestial objects and events

Published09/03/2018 , by Parke Kunkle

Let’s compare the two brightest stars currently shining in Minnesota’s evening sky. At about 9 pm in early September or 8 pm in late September, look for the bright star Vega nearly overhead. Vega is the third brightest star visible from Minnesota gleaming with a blue-white color. Its surface temperature is about 17,000 °F (7,000 degrees hotter than our star) and you could fit about 2.5 of our suns side-by-side across Vega.

In contrast, look for the second brightest star, Arcturus, above the western horizon. Arcturus is the brightest star in the constellation of Boötes, the fourth-brightest in the night sky, and the brightest in the northern celestial hemisphere. Its ruddy color indicates it is cooler than Vega and it sports a surface temperature of just 8000 °F (cooler than our star) but its diameter is about 25 times that of the sun! Our star will look like this in a few billion years.

Comparison of Acturus and our Sun

Compare other stars with this video from and the European Southern Observatory.


Keep watching the planets too. As noted below, Venus, Jupiter, Saturn and Mars continue their show during most of the month.

September Highlight Comments
1 Bright star Spica 1 degree above right of very bright Venus 8-8:30 pm, Low WSW
1 Venus low WSW, Jupiter SW, Saturn S, Mars E 8:30 pm
5 Mercury 1 ½ degrees above bright star Regulus 6:15 am, Low E
6 Mercury just left of Regulus 6:15 am, Low E
Binoculars help
12 Bright Venus 8 degrees below thin crescent Moon 7:45 pm, WSW
13 Jupiter below left of Moon 8-9 pm, WSW
16 Saturn 8 degrees left of Moon 9 pm, SSW
17 Saturn below right of Moon 9 pm, SSW
19 Mars below left of Moon 8 pm to midnight
22 Autumn begins in Northern Hemisphere
30 Bright star Aldebaran 1 degree from Moon 11:30 pm, E


When viewing planets, stars or constellations in the night sky, it is helpful to use a sky map.

Minnesota Starwatch is another great resource for tracking the night sky.

Meet up with other stargazing enthusiasts via Twin Cities Sidewalk Astronomers, MN Astronomical Society & MN Institute for Astrophysics.