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Moon and Companions

February 5, 2016

The major planets of the solar system boast an amazing assortment of moons — about 170 in all. Jupiter and Saturn each have more than 60, Mars has a couple of dinky ones, and Earth has a big one. Yet two planets have no moons at all. And those worlds appear quite close to our own Moon at first light tomorrow.

Venus, the “morning star,” stands close to the right of Moon. And fainter Mercury is even closer below the Moon, although it’s so low in the sky that it’s tough to spot.

Astronomers looked for moons around those two planets for centuries. And in the case of Venus, quite a few reported seeing a moon. The first sightings came in the 17th century, not long after the invention of the telescope. Many more sightings followed — some of them by some of the best observers around. Yet many other observers looked and looked but never saw anything.

Eventually, astronomers decided that most of the sightings, if not all of them, were actually stars that just happened to line up close to Venus at the time. And in the modern era, spacecraft have confirmed that Venus is moonless.

A few years back, though, a couple of researchers suggested that that hasn’t always been the case. Impacts between the young Venus and two giant space rocks may have blasted out enough debris to form moons. The first moon drifted off into space, while the second splatted back into Venus — leaving our nearest planetary neighbor without a moon to call its own.

Script by Damond Benningfield, Copyright 2015


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