If you’re wondering what the bright white “star” in the east is in the predawn sky this week then wonder no more—it’s Venus in its new apparition as the “Morning Star.”
This Tuesday, Sept. 19 the second planet from the sun will appear to us on Earth to be the brightest it ever gets while in the constellation Cancer, the crab. Already the brightest object in the night sky after the moon, Venus will this week reach almost its maximum magnitude, shining at -4.43. Jupiter is the only other planet that gets anywhere near as bright.
It won’t appear this bright to us again until February 2025, according to EarthSky, when it will be visible in the west after sunset.
Why Venus Is At Its ‘Greatest Brilliance’ This Week
Just like the moon, Venus has phases. “As Venus orbits the sun at a closer distance than the Earth, we can peer inward towards our star and see the planet showing crescent phases,” said Tom Kerss, astronomer and author of Observing our Solar System: A beginner’s guide, in an email.
Right now we’re looking more at Venus’ night side than its day side, just as we do when the moon is a crescent. “Venus is closest to us when it’s an extremely fine crescent, but it appears brighter when the crescent is a bit wider, even though it’s farther from us,” said Kerss. “There’s a trade off between apparent size and distance that results in Venus reaching its maximum apparent brilliance when its phase is around 30% illuminated from our perspective.”
Orbit Of Venus Explained
Venus will reach that threshold on Wednesday. “Whether it’s following the sun or leading it, Venus appears at its brightest about one month before or after its conjunction with the sun—that is the time when it overtakes us in its smaller orbit,” said Kerss. Venus takes 225 days to orbit the sun, so as well as orbiting the sun faster than Earth it always appears relatively close to the sun.
Venus drifted roughly between Earth and the sun on Aug. 13, something astronomers call inferior conjunction. At that point its was entirely backlit by the sun and invisible to us on Earth. The opposite of that is superior conjunction, which will next occur on June 4, 2024. “When Venus is moving around the far side of the sun it shows virtually its full day side to the Earth, but it appears so much smaller to us at this great distance that it doesn’t come near its apparent brightness during the 30% phase,” said Kerss.
Another reason why Venus is so bright is that it’s a cloudy planet. Its global cloud cover—made from sulphuric acid—reflects a lot of sunlight, making it seem brighter than it would otherwise be.
Best Time To See Venus (And Mercury) This Week
The best time to see Venus at its brilliant best this week is between it rising about two hours before sunrise where you are, and sunrise itself. Just look east—you won’t be able to miss it. However, if you look from about an hour before sunrise, you’ll also see tiny Mercury low in the east beneath Venus. Not nearly as bright as Venus, Mercury will fade about 30 minutes before sunrise in the gathering light of dawn.
Mercury will be in the constellation Leo, the lion, with its bright star Regulus shining roughly between the two planets. Later this week Mercury will reach its great elongation east—the farthest it gets from the sun in the morning sky.
Venus has an eight-year cycle, as seen from Earth, in which it orbits the Sun 13 times and makes eight apparitions as either the “Evening Star” or “Morning Star.”
Wishing you clear skies and wide eyes.
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