It’s a crisp, mostly clear autumn evening, and the moon has a date with Venus.
About half an hour after sunset—which thanks to the end of Daylight Savings Time now occurs just before 5 p.m. locally—the waxing crescent moon will flirt with Venus just above the horizon in the southwestern sky. Venus is stealing the show this time of year, with a magnitude of –4.46. That’s astronomer-speak for “exceedingly bright.”
Indeed, it is one of the brightest objects in the sky, 16 times brighter than Sirius, the brightest star visible at the moment, according to Universetoday.com.
“Today is also a great time to try your hand at spotting Venus in the daytime, as a 3-day old waxing crescent Moon lies about eight degrees to its upper right,” Universetoday.com says.
It may be of little surprise that Venus and the moon are such an item. One theory of how our planet came to have a satellite at all is that Mother Earth wooed the moon from her sister a few billion years ago, Space.com reported on September 27. It counters the most popular theory, which is that a huge impact during the Earth’s formative years lopped off a chunk that ended up orbiting as the moon.
However, the stolen-from-Venus theory has a ways to go before being proven, inasmuch as any of it can be more than speculation.
"We are still on the trail of the detailed scenario that would seem both likely and complete in its ability to account for all the geochemical and geophysical observations," said Sean Solomon, the director of the Lamont-Doherty Earth Observatory of Columbia University, according to Space.com. "Even with the giant impact idea, we don't know the origin of the impacting object. It could've been an early protoplanet. It could've been a moon of another object that was removed from the gravitational field of its original [planet]. It could've been a very large asteroid. All of those scenarios are still open."
For now, then, all we can do is watch Venus and the moon cavort, and enjoy. And if you miss this one, there's another in December.