The Sky Today on Tuesday, August 11: Venus, half-lit

Venus is set to reach dichotomy today, so take the chance to view it half-lit through a telescope in the evening sky. | Published: August 11, 2026 By Aug. 11, Venus is predicted to appear 50.4% lit and reach dichotomy overnight. But it may appear half-lit earlier than this date, thanks to the Schröter effect. Credit: Astronomy: Roen Kelly Looking for a sky event this week? Check out our full Sky This Week column. August 10: Open cluster NGC 7243 In the evening sky, Venus is reaching dichotomy, the moment when it is exactly half-lit. You’ll find magnitude –4.4 Venus some 20° high in the west as the Sun sets. It’s so bright, it will be the first light to pop out of the darkening sky, so you can pick it up easily in optics (make sure the Sun has completely disappeared below the horizon before doing so). In fact, observing Venus earlier in the evening is best, as the background sky makes viewing the bright planet’s phase easier. Its apparent size of 23” should also help. Look closely at that phase. Venus is predicted to appear 50.4% lit this evening, and 49.9% by tomorrow. But during evening apparitions, Venus often appears to reach dichotomy earlier than predicted — does it perhaps already appear less than 50% lit when you study it this evening? The reason this occurs is called the Schröter effect, after Johann Schröter, who first noted it in the late 18th century. Astronomers believe it’s due to the way sunlight scatters off the thick clouds blanketing the world. Consider coming back tomorrow and the next few days after that to compare the view and watch as the planet’s phase wanes. Sunrise: 6:08 A.M.Sunset: 8:02 P.M.Moonrise: 4:33 A.M.Moonset: 7:38 P.M.Moon Phase: Waning crescent (1%)*Times for sunrise, sunset, moonrise, and moonset are given in local time from 40° N 90° W. The Moon’s illumination is given at 10 P.M. local time from the same location. Alison Klesman is senior editor of Astronomy magazine. She holds a Ph.D. in astronomy and has studied a variety of topics, from minor planets to supermassive black holes.