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Look Up! The Ursid Meteor Shower Is an Early Holiday Present

A screenshot of the Earth (blue orbit) crossing the debris stream (sparkly white path) left by comet 8P/Tuttle during the comet's 14-year orbit around the Sun. Image Credit: Ian Webster

 
Two days before Hanukkah and three before Christmas, the cosmos will bring you an early holiday gift—no telescope required. The Ursid meteor shower peaks in the early morning hours of December 22, after midnight through dawn. It's not the most spectacular shower of the year, but it is the last one of 2016, and it'll tide you over until the Quadrantids next month. (And making a big production of going outside to watch the sky is a pretty good way to drop a big hint about that telescope you want for Christmas or Hanukkah.)

Danielle Moser, a meteor scientist with the Meteoroid Environment Office at NASA's Marshall Space Flight Center, tells mental_floss that you can expect to see a handful of meteors if you're patient. "Not all of the meteors you’ll see while out observing belong to the Ursid meteor shower—some are sporadic background meteors and some belong to other active showers. If you see a meteor, try to trace it backwards. If you end up near the Little Dipper, there’s a good chance you’ve seen an Ursid."

HOW 8P/TUTTLE WAS DISCOVERED… TWICE

The Ursids among the constellations. Image Credit: Stellarium

 
While some meteor showers have been studied for millennia, the Ursids have only been observed for a relatively short time. The shower's parent is comet 8P/Tuttle, discovered in 1790 by Pierre Méchain. Decades later, in 1858, it was rediscovered by Horace Tuttle, and thus earned its name. (Don't feel bad for poor Pierre, though. He discovered so many things in his lifetime that he probably wouldn't remember this meager little comet anyway.)

Around the turn of the century, William Denning, an amateur astronomer and renowned comet hunter from England, recognized the radiant, or the seeming point of origin, of the Ursid meteor shower. The association with the Tuttle comet was immediately suspected, and later observations would confirm it.

It turns out Tuttle is a "contact binary"—a small, solar system object made of two bodies that have gravitated toward each other until they touch, like the rubber-ducky shaped 67P/Churyumov–Gerasimenko. We know now that Tuttle's orbit around the Sun takes just under 14 years. As it goes about its orbit, it leaves behind a trail of particles that, over the centuries, has organized. When the Earth crosses into this debris field, those particles slam into our atmosphere and burn away. That release of energy takes the appearance of "shooting stars." A meteor shower is born.

WHEN TO WATCH

The shower appears to originate in the Little Dipper, which is how it gets its name. The formal name of the Little Dipper is Ursa Minor, which translates as Little Bear. (Of course, some will argue it looks a lot more like a spoon.)

The shower will appear highest in the sky in the hours before sunrise on December 22, so set your alarm clock accordingly. The shower can produce around 10 meteors per hour, and to see them, all you’ll need is to find a place with no light and look up.

Moser suggests that you keep a thermos of hot chocolate in your hands and your phone in your pocket. "You'll see more meteors if you let your eyes adjust to the dark," she says. "As soon as you look at a bright light source like your phone, you have to start the adjustment process all over again! And hot chocolate will keep you warm and awake while patiently braving the cold December weather."

The Ursids have had some pretty spectacular showings—most notably in 1986, with spikes on the order of 100 meteors per hour. Don't get your hopes up for a wild display in 2016, however. Rather, appreciate the Ursids for what they are: an annual tradition of rare and romantic shooting stars in a beautiful, wintry, night sky. Enjoy the last big meteor shower of the year, and if it convinces someone to gift you a telescope, get ready: There are some astounding celestial wonders waiting for us in the new year.

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Look Up! Residents of Maine and Michigan Might Catch a Glimpse of the Northern Lights Tonight
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The aurora borealis, a celestial show usually reserved for spectators near the arctic circle, could potentially appear over parts of the continental U.S. on the night of February 15. As Newsweek reports, a solar storm is on track to illuminate the skies above Maine and Michigan.

The Northern Lights (and the Southern Lights) are caused by electrons from the sun colliding with gases in the Earth’s atmosphere. The solar particles transfer some of their energy to oxygen and nitrogen molecules on contact, and as these excited molecules settle back to their normal states they release light particles. The results are glowing waves of blue, green, purple, and pink light creating a spectacle for viewers on Earth.

The more solar particles pelt the atmosphere, the more vivid these lights become. Following a moderate solar flare that burst from the sun on Monday, the NOAA Space Weather Prediction Center forecast a solar light show for tonight. While the Northern Lights are most visible from higher latitudes where the planet’s magnetic field is strongest, northern states are occasionally treated to a view. This is because the magnetic North Pole is closer to the U.S. than the geographic North Pole.

This Thursday night into Friday morning is expected to be one of those occasions. To catch a glimpse of the phenomena from your backyard, wait for the sun to go down and look toward the sky. People living in places with little cloud cover and light pollution will have the best chance of spotting it.

[h/t Newsweek]

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10 Facts About the Dwarf Planet Haumea
Kevin Gill, Flickr // CC BY-2.0
Kevin Gill, Flickr // CC BY-2.0

In terms of sheer weirdness, few objects in the solar system can compete with the dwarf planet Haumea. It has a strange shape, unusual brightness, two moons, and a wild rotation. Its unique features, however, can tell astronomers a lot about the formation of the solar system and the chaotic early years that characterized it. Here are a few things you need to know about Haumea, the tiny world beyond Neptune.

1. THREE HAUMEAS COULD FIT SIDE BY SIDE IN EARTH.

Haumea is a trans-Neptunian object; its orbit, in other words, is beyond that of the farthest ice giant in the solar system. Its discovery was reported to the International Astronomical Union in 2005, and its status as a dwarf planet—the fifth, after Ceres, Eris, Makemake, and Pluto—was made official three years later. Dwarf planets have the mass of a planet and have achieved hydrostatic equilibrium (i.e., they're round), but have not "cleared their neighborhoods" (meaning their gravity is not dominant in their orbit). Haumea is notable for the large amount of water ice on its surface, and for its size: Only Pluto and Eris are larger in the trans-Neptunian region, and Pluto only slightly, with a 1475-mile diameter versus Haumea's 1442-mile diameter. That means three Haumeas could fit sit by side in Earth—and yet it only has 1/1400th of the mass of our planet.

2. HAUMEA'S DISCOVERY WAS CONTROVERSIAL.

There is some disagreement over who discovered Haumea. A team of astronomers at the Sierra Nevada Observatory in Spain first reported its discovery to the Minor Planet Center of the International Astronomical Union on July 27, 2005. A team led by Mike Brown from the Palomar Observatory in California had discovered the object earlier, but had not reported their results, waiting to develop the science and present it at a conference. They later discovered that their files had been accessed by the Spanish team the night before the announcement was made. The Spanish team says that, yes, they did run across those files, having found them in a Google search before making their report to the Minor Planet Center, but that it was happenstance—the result of due diligence to make sure the object had never been reported. In the end, the IAU gave credit for the discovery to the Spanish team—but used the name proposed by the Caltech team.

3. IT'S NAMED FOR A HAWAIIAN GODDESS.

In Hawaiian mythology, Haumea is the goddess of fertility and childbirth. The name was proposed by the astronomers at Caltech to honor the place where Haumea's moon was discovered: the Keck Observatory on Mauna Kea, Hawaii. Its moons—Hi'iaka and Namaka—are named for two of Haumea's children.

4. HAUMEA HAS RINGS—AND THAT'S STRANGE.

Haumea is the farthest known object in the solar system to possess a ring system. This discovery was recently published in the journal Nature. But why does it have rings? And how? "It is not entirely clear to us yet," says lead author Jose-Luis Ortiz, a researcher at the Institute of Astrophysics of Andalusia and leader of the Spanish team of astronomers who discovered Haumea.

5. HAUMEA'S SURFACE IS EXTREMELY BRIGHT.

In addition to being extremely fast, oddly shaped, and ringed, Haumea is very bright. This brightness is a result of the dwarf planet's composition. On the inside, it's rocky. On the outside, it is covered by a thin film of crystalline water ice [PDF]—the same kind of ice that's in your freezer. That gives Haumea a high albedo, or reflectiveness. It's about as bright as a snow-covered frozen lake on a sunny day.

6. HAUMEA HAS ONE OF THE SHORTEST DAYS IN THE ENTIRE SOLAR SYSTEM.

If you lived to be a year old on Haumea, you would be 284 years old back on Earth. And if you think a Haumean year is unusual, that's nothing next to the length of a Haumean day. It takes 3.9 hours for Haumea to make a full rotation, which means it has by far the fastest spin, and thus shortest day, of any object in the solar system larger than 62 miles.

7. HAUMEA'S HIGH SPEED SQUISHES IT INTO A SHAPE LIKE A RUGBY BALL.

haumea rotation gif
Stephanie Hoover, Wikipedia // Public Domain

As a result of this tornadic rotation, Haumea has an odd shape; its speed compresses it so much that rather than taking a spherical, soccer ball shape, it is flattened and elongated into looking something like a rugby ball.

8. HIGH-SPEED COLLISIONS MAY EXPLAIN HAUMEA'S TWO MOONS.

Ortiz says there are several mechanisms that can have led to rings around the dwarf planet: "One of our favorite scenarios has to do with collisions on Haumea, which can release material from the surface and send it to orbit." Part of the material that remains closer to Haumea can form a ring, and material further away can help form moons. "Because Haumea spins so quickly," Ortiz adds, "it is also possible that material is shed from the surface due to the centrifugal force, or maybe small collisions can trigger ejections of mass. This can also give rise to a ring and moons."

9. ONE MOON HAS WATER ICE—JUST LIKE HAUMEA.

Ortiz says that while the rings haven't transformed scientists' understanding of Haumea, they have clarified the orbit of its largest moon, Hi'iaka—it is equatorial, meaning it circles around Haumea's equator. Hi'iaka is notable for the crystalline water ice on its surface, similar to that on its parent body.

10. TRYING TO SEE HAUMEA FROM EARTH IS LIKE TRYING TO LOOK AT A COIN MORE THAN 100 MILES AWAY.

It's not easy to study Haumea. The dwarf planet, and other objects at that distance from the Sun, are indiscernible to all but the largest telescopes. One technique used by astronomers to study such objects is called "stellar occultation," in which the object is observed as it crosses in front of a star, causing the star to temporarily dim. (This is how exoplanets—those planets orbiting other stars—are also often located and studied.) This technique doesn't always work for objects beyond the orbit of Neptune, however; astronomers must know the objects' orbits and the position of the would-be eclipsed stars to astounding levels of accuracy, which is not always the case. Moreover, Ortiz says, their sizes are oftentimes very small, "comparable to the size of a small coin viewed at a distance of a couple hundred kilometers."

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