Sun

A slowdown at the sun’s surface explained

The Sun
SOLAR SLOWDOWN The sun’s surface rotates more slowly than its inner layers. Scientists now have an explanation: Photons leaving the sun could carry angular momentum away, slowing the top layer’s spin.

Never underestimate the power of a little sunlight.

Light particles, or photons, emitted from the sun’s surface, could explain a long-standing solar mystery — why the sun’s outermost layers rotate more slowly than its core.

Because the sun isn’t a solid ball, regions at different depths or latitudes rotate at different rates. For decades, scientists have wondered why the outer 5 percent of the…

5 Cratered Facts About Mercury

Mercury is the closest planet to the sun, and you would be forgiven for thinking it’s just a boring lump of rock. After all, there’s nothing interesting on it like aliens or places to drink. Still, Mercury is probably a more interesting place than you think…

1. IT HAS WATER ICE.

Although you would be forgiven for thinking Mercury, being the closest planet to the Sun, is one of the hottest places in the solar system, it in fact is subject to enormous temperature fluctuations. Some regions reach 800°F, but without an atmosphere to retain heat, Mercury’s poles and nightside of the planet plunge well below even the coldest temperatures recorded on Earth. With some regions never getting above -279°F, conditions are perfect for ice to form. Mercury’s regolith is home to possibly a trillion tons of ice, which would make it one of the wettest places in the solar system.

Fitting, then, that the ancient Chinese called it the Water Star.

2. IT ONCE HAD AN IMAGINARY FRIEND CALLED VULCAN.

In the 19th century, scientists were smug in the knowledge that they knew everything there was to know. There were of course a couple of curiosities that they could not understand, one being the precession in the orbit of Mercury. That is to say, Mercury goes around the Sun in an ellipse rather than in a circle, and the ellipse changed the direction it was pointing from time to time. It was thought that there must be a new planet between Mercury and the sun that was changing its orbit—the planet Vulcan. But despite trying, the planet could not be observed.

Albert Einstein eventually disproved the theory of Vulcan via the general theory of…

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…