Jupiter is Back (Astronomy: Week of 5/6/18)

A lot has happened in the two weeks I’ve gone silent… spring has sprung, the evening peepers have given way to Chuck-Will’s-Widows and both screech and barred owl calls. Trees have leafed out (and flowered, as copious pollen can attest), and I’ve watched redbuds, dogwoods, wisteria, and locust trees bloom. In the meantime, I’ve been sick, and working 15-hour days (fortunately not at the same time) – and my appreciation for all this stuff has been forced to take a back seat. It’s definitely a reminder that as self-centered as we humans can be, the world soldiers on to its own rhythm, whether we can catch up or not.

The night sky has changed a lot too – winter stars are setting in the west along with the Sun now. The spring triangle (Arcturus, Spica, Denebola) is high in the sky after sunset, with Leo almost straight up. And the first of the summer triangle stars (Vega) is shining low in the northeast right after sunset.

After a winter with no evening planets, the two brightest are sharing the same night sky now. Right after sunset, in the west, Venus is shining high and bright. It’s orbital speed is close enough to Earth’s that its closure “from behind” is slow – it will be hanging in the west as the Evening Star for quite some time.

On the other side of the sky, Jupiter is finally pulling into the evening. On Tuesday night (May 8), it will be at opposition – directly opposite the Sun from us. That means a couple things: it’s at its fullest, its closest approach to us on this orbit, and it’s rising just as the Sun sets, visible now all night long.

Jupiter never fails to be an interesting telescopic target – cloud bands are easily visible even in small scopes, and the 4 Galilean Moons (Ganymede, Callisto, Io, Europa) pop even with binoculars. Their movement is so rapid, and obvious, that anyone can observe the dynamics of this system with minimal effort. It’s a big system too – by itself, Jupiter has more than 2.5 times the mass of all the other planets, combined. And Ganymede, the largest Jovian moon, is actually larger than Mercury.

So even though winter clarity is giving way to summer haze, warm nights still provide a lot of opportunity to marvel at nature. Go out and take a look at Jupiter, listen to the owls, and enjoy.