08/17/2021 – Ephemeris – Jupiter is big and bright in the evening

This is Bob Moler with Ephemeris for Tuesday, August 17th. Today the Sun will be up for 13 hours and 56 minutes, setting at 8:44, and it will rise tomorrow at 6:49. The Moon, 2 days past first quarter, will set at 2:02 tomorrow morning.

The brilliant planet we see rising in the east-southeast in the evening is not Venus, which is low in the west, ensnared in evening twilight. It’s Jupiter, the second-brightest planet and the largest by far. Jupiter would be the brightest planet except that the strength of sunlight falling on it is only 1/25th of what we get on the Earth and less than 1/50th of what Venus gets. Plus, it’s a lot farther away. Even in binoculars, Jupiter appears as not quite star-like. Most of the time, Jupiter is the largest appearing planet in telescopes. It is only beaten by Venus for a couple of months when it is nearest to us. When I was a kid, just learning about the planets, Jupiter had 12 moons. Astronomers by now have discovered 68 more.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hr). They may be different for your location.

Addendum

Jupiter finder animation for tonight, August 17, 2021, at 9:15 pm. Venus i is in the west, which is brighter but suffering in bright twilight. Saturn may not be as easily visible as it is shown here until later. Credit: Stellarium and GIMP.