Venus continues to shine as a Morning Star in the eastern sky during September.
by Jeffrey L. Hunt.
Click an image to see a slideshow of Venus images for September 2020.
As the days noticeably shorten, Venus continues its spectacular appearance in the eastern morning sky.
See our feature about Venus in the morning sky.
The chart above shows the motion of the planet compared to the starry background.
On September 1, Venus rise nearly 3.75 hours before sunrise, and it is high above the skyline as morning twilight brightens the eastern sky. By month’s end it rises nearly 3.5 hours before sunrise. So, it remains “that bright star” in the eastern sky.
During September the planet is in eastern Gemini and it continues to work its way eastward through the zodiacal constellations. During the month, the planet moves into Cancer with its dimmer stars. Near month’s end it moves into Leo.
As Earth revolves around the sun, the stars rise about 4 minutes earlier each morning. During the course of a month, they rise two hours earlier by month’s end. This slow westward march of the constellations helps us mark the seasons in the sky.
As the stars rise earlier, Venus steps eastward each morning. Consequently, it is nicely placed in the sky to be easily noticed.
In the sky, Venus keeps nearly a constant spot and the stars seem to move past it when observed at the same time each morning.
Early in the month, Saturn departs the sky as Venus rises, leaving Venus and Mars in the morning sky.
On the morning of September 14, the crescent moon and Venus appear near the Beehive star cluster. While not as bright as the famous Pleiades star cluster, the Beehive appears as a fuzzy cloud. A binocular provides a good view of the cluster.
The bright planet then continues to glide eastward toward Leo, stepping into the constellation on September 23.
Even with the planet’s brilliance, use a binocular to track it through the starfield.
In the notes that follow the “m” numbers indicate the brightness of Venus and the stars. The smaller the number, the brighter the star or planet. Venus has a negative number to show its brilliance. The stars with magnitude 1 are among the brightest in our sky. As the number increases toward 4 and 5, they are among the dimmer stars visible to the unaided eye. Some of the stars have Greek letters designating their names. When the letter of the star and its genitive name are used, a star like Pollux is also known as Beta Geminorum (β Gem) to indicate that its Beta in the constellation Gemini. Additionally, with the Greek letter, the constellation is abbreviated, Gemini (Gem), Cancer (Cnc).
Numbers are used to name stars when the Greek alphabet is exhausted, like 81 Geminorum or 20 Cancri.
Detailed daily notes for observing planets are found here. In the notes that follow, the observations are for one hour before sunrise, when Venus is about 30° up in the sky; that’s about one-third of the way from the natural horizon to overhead.
- September 1: One hour before sunrise brilliant Venus (m = −4.3) is less than 30° up in the east in Gemini. It is 8.6° to the lower right of Pollux (m = 1.2). With a binocular notice that it is below a line that connects Pollux and Kapa Geminorum (κ Gem, m = 3.6) and extends downward to Procyon (α CMi, m = 0.4).
- September 2: Venus (V) rises as Saturn sets. The morning sky now has two bright planets – Venus and Mars.
- September 3: V is 0.9° to the right of 85 Geminorum (85 Gem, m = 5.4).
- September 4: V moves into Cancer, over 9° to the lower right of Pollux and over 11° to the upper right of Delta Cancri (δ Cnc, m = 3.9).
- September 7: V is 0.9° to the upper left of Zeta Cancri (ζ Cnc, m = 5.2). Use a binocular.
- September 10: V is 0.5° below 20 Cancri (20 Cnc, m = 5.9).
- September 11: V is 0.5° to the upper right of Theta Cancri (θ Cnc, m = 5.3). Use a binocular to spot the Beehive cluster to the lower left of Venus. The cluster appears as a patch of stars, like sparkling jewels on the velvet of the sky.
- September 12: Through a binocular, V is 2.5° to the right of the Beehive cluster. The moon (24.3 days past the New Moon phase, 30% illuminated), nearly 50° up in the east and over 20° above V. The lunar orb is over 10° to the upper right of Castor (α Gem, m =1.6).
- September 13: V passes 2.3° to the lower right of the Beehive cluster. The planet is also 1.5° to the upper right of δ Cnc. The waning crescent moon (25.3d, 20%) is over 10° above V.
- September 14: V is 5.0° to the right of the crescent moon (26.3d, 12%) and 0.9° to the lower right of δ Cnc. With a binocular observe that the Beehive cluster is 2.7° to the upper left of V and 4.6° to the upper right of the lunar crescent.
- September 15: V is nearly 28° up in the east. It is 1.4° to the lower right of δ Cnc and 3.3° to the lower right of M44. All three of these objects are nearly along a line that starts with the star cluster and ends with V. The moon (27.2d, 6%) is about 15° up in the east.
- September 16: V is 4.2° below the Beehive cluster, 2.3° below δ Cnc, and 1.8° to the upper left of Omicron Cancri (ο Cnc, m =5.2).
- September 21: V is 0.5° to the upper left of Pi Cancri (π Cnc, m = 5.3).
- September 23: V moves into Leo, 11.0° to the upper right of Regulus (α Leo, m = 1.3).
- September 25: V passes 3.1° to the upper left of Xi Leonis (ξ Leo, m = 5.0).
- September 28: V passes 3.8° to the upper left of Omicron Leonis (ο Leo, m = 3.5).
- September 30: V ends the month 0.4° above Nu Leonis (ν Leo, m = 5.2) and 2.9° to the upper right of Regulus.
January 20, 2021: Mercury is low in the west-southwest after sunset. The bright moon is to the lower right of Mars, while the Red Planet passes planet Uranus.
January 19, 2021: Mercury is low in the west-southwest after sunset. The moon is approaching Mars before their grouping tomorrow evening. Mars nears the planet Uranus before tomorrow’s conjunction.
January 18, 2021: Without a bright morning planet, bright Arcturus and the constellation Bootes the Herdsman is high in the south. The crescent moon is in the early evening sky. Mars is near the planet Uranus. They are high in the south-southeast as night falls.