Earth

Venus Will Be Bright and a Little Strange Tonight

Look at the sky just after sunset tonight, January 12, and you’re guaranteed to know immediately which point of light is Venus. Hint: It will be the astonishingly bright one. Now get your telescope. As the planet arrives at its greatest angular distance to the east of the Sun, you won’t be able to see surface features, as you sometimes can when looking at Mars, or identify stunning cloud swirls as you might see when viewing Jupiter, because Venus’s thick and unforgiving clouds conceal the planet’s mountains below. But with the help of a telescope, you’ll be able to see that Venus doesn’t appear to be a full circle.

Here’s why: it’s at greatest eastern elongation tonight. What’s that? Elongation is the angle between the planet and the Sun from Earth. To understand elongation, point at the Sun as it sets. With your other hand, point at Venus. Simply put, the angle that your arms make is the elongation. Because planets are ever in motion and orbiting at speeds different from one another, that angle is ever in flux. Repeat this process in March and you’ll notice a big difference in the directions of your arms.

The largest this angle will ever get in an orbit is its greatest elongation. When greatest elongation occurs at sunset, it’s said to be at greatest eastern elongation. That’s what we have tonight. When it occurs at sunrise, it is at greatest western…

Look Up Again! The Final Supermoon of 2016 Rises Tonight

You might be sick to death of hearing about “supermoons.” If that’s the case, I bring good news: tonight, December 13, you’ll see the final supermoon of 2016. If you’re not sick of them, I also bring good news, because you have one more supermoon to see.

Of course, where there is good news there is bad, and it’s this: The supermoon will make it very difficult to catch the Geminid meteor shower, which peaks tonight. Don’t give up, however; because of the sheer volume of meteors that comprise the Geminids, you might see some shooting across the sky.

Before last year, when the red harvest supermoon took over the world, you might never have heard of a supermoon. And now we’ve had three in a row to close out the year: October’s super hunter’s moon, November’s super beaver moon, and now December’s full cold or long nights supermoon. This is true in part because supermoon is not an astronomy term, but rather, one of astrology. (In case you are wondering about the difference: astronomy is science; astrology is make believe.) The name has stuck of late because it’s Twitter-friendly and a lot easier to remember than the actual name for the phenomenon: perigee-syzygy of the Earth–Moon–Sun system.

If you want to understand what’s going on and why there are so many supermoons recently, you really do need to look at the proper name. Perigee occurs when the Moon is…