Evening Mercury

Four of the five planets that are visible to the unaided eye line up in the early morning sky right now. Only one bucks that trend: Mercury, the Sun’s closest and smallest planet. It’s quite low in the west-northwest as evening twilight begins to fade. It’s bright, though, so if you have a clear horizon, you should be able to spot it.

Mercury will climb higher into the sky over the next couple of weeks. It’ll stand highest on the evenings of the 28th and 29th, providing a little more time to look for it. On the other hand, the planet will get fainter over that period as well. On the 29th, it’ll be about a third as bright as it is tonight.

Several factors are responsible for the changes.

First, Mercury is moving from behind the Sun. It’ll stand farthest from the Sun in our sky late in the month. So each evening, it climbs a little higher into the sky.

Second, the planet is moving closer to Earth — it’ll be about 27 million miles closer on the 29th than it is today. That tends to make it look a little brighter.

But the third factor works the other way. Mercury’s phase is changing, just as the phases of the Moon change. Tonight, the Sun lights up about three quarters of the hemisphere that faces our way. By the 29th, though, it’ll light up only about a third. So while Mercury will be a lot closer to us, it’ll look fainter.

Still, it’s well worth looking for — the only planet in the evening sky.
 

Script by Damond Benningfield