During September 2025, brilliant Venus dims slightly as it crosses Cancer and Leo before sunrise. Watch its close conjunction with Regulus on September 19, joined by the crescent moon.
by Jeffrey L. Hunt
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Venus Summary Article
Venus During September
After appearing with the rich star fields of Taurus and Gemini, Venus crosses Cancer and Leo. From suburban settings the Crab is the largely empty region between Gemini’s Pollux and Leo’s Regulus. It has fainter stars and a pretty star cluster that is easily seen from the countryside.
In contrast, Leo’s stars outline the silhouette of the Lion. A backwards question mark shape, with Regulus at the bottom, outlines the Lion’s head. The pattern is known as the Sickle of Leo, for the farmer’s cutting tool. The haunches and tail, Denebola, are dotted by a triangle.
Since the greatest brilliancy, during late April, Venus’ brightness dimmed 45%. During September the planet’s distance from Earth increases 13 million miles while the phase increases to a 91%-lit, morning gibbous phase.
The planet is heading toward its solar conjunction during early January. During this month the apparent separation, known as the elongation, decreases 7°. This is reflected in the Morning Star’s rising time interval compared to sunrise, which loses 36 minutes. At month’s end, the planet rises 124 minutes before sunrise.
As the seasonal sunrise point shifts southward along the horizon by 15°, Venus’ rising point changes by the same amount. It still rises farther north along the horizon than the sun. When the sun rises near the east point on the equinox, Venus rises earlier that morning in the east-northeast.
Look for the planet in the eastern sky about 15° above the eastern horizon.
September’s Venus Highlights
Here’s what to see this month:
On September 1st, Venus, stepping eastward in front of Cancer, is 20° to Jupiter’s lower left.
Through a binocular, the Morning Star is 1.3° to the lower right of the Beehive star cluster, cataloged as Messier 44, also known as the Praesepe. For the next two mornings watch it pass and move away from Asellus Australis, a star in the Crab’s body.
Venus and Sirius
For approximately six days beginning on the 4th, Venus and Sirius are nearly the same altitude – height above the horizon – during morning twilight. While they are 45° apart in the sky, the brightest planet and the brightest star dominate the eastern sky.
Venus Crosses the Leo Border
Venus continues to step eastward toward Leo, crossing the border on the 10th.
On the morning of the 15th, Venus is 5.1° to Regulus’ upper right, Leo’s brightest star, and closing on a close conjunction with the star on the 19th.
Rare Tight Group: Venus, Moon, Regulus
On conjunction morning, Venus passes 0.5° to Regulus’ upper left, while the pretty crescent moon, 5% illuminated, is 0.5° to Venus’ upper left. The three celestial wonders easily fit into a binocular field as they fit into a circle 1.3° across, about the diameter across your thumb when your arm is extended. Venus, Moon, and Regulus do not fit into a binocular field again until September 22, 2041!
Venus continues its eastward journey in front of Leo, passing dimmer stars in the constellation.
Morning Star at Month’s End
At month’s end, the Morning Star stands less than 14° up in the east, over 13° to Regulus’ lower left and about the same distance to Denebola’s upper right, the Lion’s tail.
Watch the brilliant Morning Star in the eastern sky before sunrise as it passes stars in Cancer and Leo.
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