Newsletter Archive

The Entire Solar System?

September 7, 2021


Hi everyone!

Coming up in October we'll have another nice meteor shower, and in November we'll have another lunar eclipse. For this month, I'd like to direct your attention to the solar system in the sky again, because for the next few days, you can see most of the solar system arrayed in the evening skies.

Facing South, About an Hour After Sunset

This picture shows the view from Iowa tonight, facing south, 45 minutes or an hour after sunset. Notice Scorpius and the teapot of Sagittarius low in the south. (If you live farther north than I do, Scorpius and Sagittarius will be lower and even harder to see. If you live in Canada or Europe, you will only be able to see the upper stars, if any at all. If you live in the southern hemisphere, you can see the same scene, but it will be upside-down high in your northern sky.) The area around Scorpius and Sagittarius is especially pretty, and worth scanning with binoculars or a telescope. If you have dark skies, you may notice a particularly bright and beautiful "knot" of the Milky Way just above Sagittarius. It looks like steam emerging from the spout of the teapot. That's the "Milky Way Core", i.e. the center of the Milky Way galaxy, and that part of the sky is especially rich with telescope treasures.

High overhead will be the Summer Triangle, connecting Vega, Deneb, and Altair, three of the brightest stars in the sky, and forming a useful landmark and compass arrow. (It points approximately south.) Above Scorpius is a U-shaped curve of stars (Serpens), joined to the bottom of a coffin-shaped pentagon of stars (the "Coffin of Ophiuchus"). Together they make a doctor wrestling with a snake (Ophiuchus and Serpens).

And arcing across the low southern sky, through the upper portions of Scorpius and Sagittarius, is the "planet highway", or the zodiac. You can see it marked by the sun on one end, and bright Jupiter on the other, with Saturn and Venus in between. Mercury and Mars are there, too, although they are so close to the sun that you probably won't see them. If you have a very clear western horizon, you might be able to catch Mercury just before it sets, but Mars is now effectively invisible. (You may remember that Mars was at opposition last October, and has been slowly crossing the evening sky ever since. It has now reached the sun, and will pass it in a few weeks, in October.)

The new moon was yesterday, the 6th, meaning that if you like beautiful sunsets, you should watch them for the next few days. The graceful sliver of the waxing crescent moon will join the sunset scene, and as the days go by it will march along the zodiac away from the sun and towards Jupiter. This means that Mercury, Venus, Jupiter, Saturn, and the moon will all be visible in the coming evenings. If you count the sun just below the horizon, and Mars right next to the sun, that's the entire visible solar system!

Enjoy the sunsets!

John