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Look Up! A "Ring of Fire" Eclipse Blazes the Southern Hemisphere

An annular solar eclipse on May 20, 2012 as seen from Chaco Culture National Historical Park in Nageezi, Arizona. Image credit: Stan Honda/AFP/Getty Images

If you're in the Southern Hemisphere, look up tomorrow morning, February 26, and brace yourself. You are going to see the Sun, big and bright as usual—that is, until it turns into a ball of black surrounded by a ring of fire. It’s the sort of sight that begs for two question marks: What is going on up there?? The answer is an annular eclipse. Like its more famous cousin, the total solar eclipse, an annular eclipse involves the moon crossing in front of the Sun. When we’re talking about eclipses, however, not all moons are created equal.

For an eclipse to be “total,” the Sun must be completely obscured by the Moon, leaving only the Sun’s corona shimmering around a black disc. When this happens, the darkest part of the moon’s shadow—the umbra—is cast across the Earth. When viewing this from the zone of totality, where alignment is perfect, day will turn to night (and look around: animals will behave accordingly).

Because the Moon’s orbit is not a perfect circle, it sometimes appears smaller in the sky than at other times. If this “smaller” moon crosses in front of the Sun, you get an annular eclipse. A tremendous black disc will still appear within the Sun but will not obscure our star completely. Rather than witnessing the spectacular view of the Sun’s corona, you’ll see the spectacular view of a fiery sky circle. Day will not turn to night when this happens. Earth at that moment will be in the Moon’s antumbra—that is, a weaker shadow beyond the tip of the umbra.

A swath of South America and Africa—mainly in the southern parts of the continents—will experience this particular eclipse. It will begin on February 26, 2017 at 7:10 a.m. ET, and reach its maximum at 9:58 a.m. NASA Goddard Space Flight Center has a map of the eclipse’s path here. Don’t live in the Southern Hemisphere? Don’t feel left out! On August 24, 2017, a small path across the United States—Oregon to South Carolina—will experience a total solar eclipse.

LOOK UP—BUT ONLY WITH SAFE EYEWEAR

Another view of the annular eclipse on May 20, 2012 as captured by the joint JAXA/NASA Hinode mission. Image credit: JAXA/NASA/Hinode via Flickr // CC BY 2.0

 
It’s interesting to consider that every day, a giant ball of fire hangs in the sky and we can never really get a good look at it without going blind. If you’re interested in seeing the eclipse tomorrow in person, you’re going to have to go toe-to-toe with a spherical celestial fusion reactor. Your eyes are no match for this, which means you will need special glasses.

DO NOT WEAR REGULAR SUNGLASSES. Stare at the Sun wearing nothing but Ray-Bans and the only good news will be that you can wear them indoors forever thereafter, because you will be blind. The tinted windows in your car, the x-ray film your friend at the hospital swears will work—none of these things will protect you from a lifetime of charred and lifeless retinas. There are no half measures where the Sun is concerned.

There are four things you can wear to look at an eclipse: welder’s goggles with a 14+ rating; special eclipse glasses; a “pinhole projector”; and a specially filtered telescope. Welding goggles can be found at industrial equipment stores, but be sure to get the correct shade—not just any goggles will do, and there is a good chance you are wrong. Eclipse glasses are available at specialty shops, though you'll need to beware of fakes. If you’re a teacher, you can make the eclipse a class event by allowing your students to make pinhole projectors themselves. It requires nothing more than a cardboard box, paper, and aluminum foil.

If all of this sounds like a bit much, or if it’s a cloudy day where you are, you have options! Our friends at Slooh will be covering it, broadcasting footage of the eclipse with commentary from astronomers and solar scientists. Coverage begins on February 26 at 7:00 a.m. ET.

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10 Astonishing Things You Should Know About the Milky Way
Anne Dirkse, Flickr // CC BY-SA 2.0
Anne Dirkse, Flickr // CC BY-SA 2.0

Our little star and the tiny planets that circle it are part of a galaxy called the Milky Way. Its name comes from the Greek galaxias kyklos ("milky circle") and Latin via lactea ("milky road"). Find a remote area in a national park, miles from the nearest street light, and you'll see exactly why the name makes sense and what all the fuss is about. Above is not a sky of black, but a luminous sea of whites, blues, greens, and tans. Here are a few things you might not know about our spiraling home in the universe.

1. THE MILKY WAY IS GIGANTIC.

The Milky Way galaxy is about 1,000,000,000,000,000,000 kilometers (about 621,371,000,000,000,000 miles) across. Even traveling at the speed of light, it would still take you well over 100,000 years to go from one end of the galaxy to the other. So it's big. Not quite as big as space itself, which is "vastly, hugely, mind-bogglingly big," as Douglas Adams wrote, but respectably large. And that's just one galaxy. Consider how many galaxies there are in the universe: One recent estimate says 2 trillion.

2. IT'S JAM-PACKED WITH CELESTIAL STUFF.

artist's illustration of the milky way galaxy and its center
An artist's concept of the Milky Way and the supermassive black hole Sagittarius A* at its core.
ESA–C. Carreau

The Milky Way is a barred spiral galaxy composed of an estimated 300 billion stars, along with dust, gas, and celestial phenomena such as nebulae, all of which orbits around a hub of sorts called the Galactic Center, with a supermassive black hole called Sagittarius A* (pronounced "A-star") at its core. The bar refers to the characteristic arrangement of stars at the interior of the galaxy, with interstellar gas essentially being channeled inward to feed an interstellar nursery. There are four spiral arms of the galaxy, with the Sun residing on the inner part of a minor arm called Orion. We're located in the boondocks of the Milky Way, but that is OK. There is definitely life here, but everywhere else is a question mark. For all we know, this might be the galactic Paris.

3. FOR A SPIRAL GALAXY, IT'S PRETTY TYPICAL …

If you looked at all the spiral galaxies in the local volume of the universe, the Milky Way wouldn't stand out as being much different than any other. "As galaxies go, the Milky Way is pretty ordinary for its type," Steve Majewski, a professor of astronomy at the University of Virginia and the principal investigator on the Apache Point Observatory Galactic Evolution Experiment (APOGEE), tells Mental Floss. "It's got a pretty regular form. It's got its usual complement of star clusters around it. It's got a supermassive black hole in the center, which most galaxies seem to indicate they have. From that point of view, the Milky Way is a pretty run-of-the-mill spiral galaxy."

4. …AND YET IT STANDS OUT AMONG ALL GALAXIES.

On the other hand, he tells Mental Floss, spiral galaxies in general tend to be larger than most other types of galaxies. "If you did a census of all the galaxies in the universe, the Milky Way would seem rather unusual because it is very big, our type being one of the biggest kinds of galaxies that there are in the universe." From a human perspective, the most important thing about the Milky Way is that it definitely managed to produce life. If they exist, the creatures in Andromeda, the galaxy next door (see #9), probably feel the same way about their own.

5. FIGURING OUT ITS STRUCTURE FROM THE INSIDE IS A CHALLENGE.


John McSporran, Flickr // CC BY 2.0

We have a very close-up view of the phenomena and forces at work in the Milky Way because we live inside of it, but that internal perspective places astronomers at a disadvantage when it comes to determining a galactic pattern. "We have a nice view of the Andromeda galaxy because we can see the whole thing laid out in front of us," Majewski says. "We don't have that opportunity in the Milky Way."

To figure out its structure, astronomers have to think like band members during a football halftime show. Though spectators in the stands can easily see the letters and shapes being made on the field by the marchers, the band can't see the shapes they are making. Rather, they can only work together in some coordinated way, moving to make these patterns and motions on the field. So it is with telescopes and stars.

6. INTERSTELLAR DUST BLOCKS OUR VIEW OF SOME PARTS OF THE GALAXY.

Interstellar dust further stymies astronomers. "That dust blocks our light, our view of the more distant parts of the Milky Way," Majewski says. "There are areas of the galaxy that are relatively obscured from view because they are behind huge columns of dust that we can't see through in the optical wavelengths that our eyes work in." To ameliorate this problem, astronomers sometimes work in longer wavelengths such as radio or infrared, which lessen the effects of the dust.

7. THE MILKY WAY SPINS, BUT ITS SPEED DOESN'T ADD UP …

Astronomers can make pretty reasonable estimates of the mass of the galaxy by the amount of light they can see. They can count the galaxy's stars and calculate how much those stars should weigh. They can account for all the dust in the galaxy and all of the gas. And when they tally the mass of everything they can see, they find that it is far short of what is needed to account for the gravity that causes the Milky Way to spin.

In short, our Sun is about two-thirds of the way from the center of the galaxy, and astronomers know that it goes around the galaxy at about 144 miles per second. "If you calculate it based on the amount of matter interior to the orbit of the Sun, how fast we should be going around, the number you should get is around 150 or 160 kilometers [93–99 miles] per second," Majewski says. "Further out, the stars are rotating even faster than they should if you just account for what we call luminous matter. Clearly there is some other substance in the Milky Way exerting a gravitational effect. We call it dark matter."

8. … AND WE BLAME DARK MATTER FOR THAT.

Dark matter is a big problem in galactic studies. "In the Milky Way, we study it by looking at the orbits of stars and star clusters and satellite galaxies, and then trying to figure out how much mass do we need interior to the orbit of that thing to get it moving at the speed that we can measure," Majewski says. "And so by doing this kind of analysis for objects at different radii across the galaxy, we actually have a fairly good idea of the distribution of the dark matter in the Milky Way—and yet we still have no idea what the dark matter is."

9. THE MILKY WAY IS ON A COLLISION COURSE WITH ANDROMEDA. BUT DON'T PANIC.

andromeda galaxy
The Andromeda galaxy
ESA/Hubble & NASA

Sometime in the next 4 or 5 billion years, the Milky Way and Andromeda galaxies will smash into each other. The two galaxies are about the same size and have about the same number of stars, but there is no cause for alarm. "Even though there are 300 billion stars in our galaxy and a comparable number, or maybe more, in Andromeda, when they collide together, not a single star is expected to hit another star. The space between stars is that vast," Majewski says.

10. WE'RE THROWING EVERYTHING WE HAVE AT STUDYING IT.

There are countless spacecraft and telescopes studying the Milky Way. Most famous is the Hubble Space Telescope, while other space telescopes such as Chandra, Spitzer, and Kepler are also returning data to help astronomers unlock the mysteries of our swirling patch of stars. The next landmark telescope in development is NASA's James Webb Space Telescope. It should finally launch in 2019. Meanwhile, such ambitious projects as APOGEE are working out the structure and evolution of our spiral home by doing "galactic archaeology." APOGEE is a survey of the Milky Way using spectroscopy, measuring the chemical compositions of hundreds of thousands of stars across the galaxy in great detail. The properties of stars around us are fossil evidence of their formation, which, when combined with their ages, helps astronomers understand the timeline and evolution of the galaxy we call home. 

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Mysterious 'Hypatia Stone' Is Like Nothing Else in Our Solar System
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In 1996, Egyptian geologist Aly Barakat discovered a tiny, one-ounce stone in the eastern Sahara. Ever since, scientists have been trying to figure out where exactly the mysterious pebble originated. As Popular Mechanics reports, it probably wasn't anywhere near Earth. A new study in Geochimica et Cosmochimica Acta finds that the micro-compounds in the rock don't match anything we've ever found in our solar system.

Scientists have known for several years that the fragment, known as the Hypatia stone, was extraterrestrial in origin. But this new study finds that it's even weirder than we thought. Led by University of Johannesburg geologists, the research team performed mineral analyses on the microdiamond-studded rock that showed that it is made of matter that predates the existence of our Sun or any of the planets in the solar system. And, its chemical composition doesn't resemble anything we've found on Earth or in comets or meteorites we have studied.

Lead researcher Jan Kramers told Popular Mechanics that the rock was likely created in the early solar nebula, a giant cloud of homogenous interstellar dust from which the Sun and its planets formed. While some of the basic materials in the pebble are found on Earth—carbon, aluminum, iron, silicon—they exist in wildly different ratios than materials we've seen before. Researchers believe the rock's microscopic diamonds were created by the shock of the impact with Earth's atmosphere or crust.

"When Hypatia was first found to be extraterrestrial, it was a sensation, but these latest results are opening up even bigger questions about its origins," as study co-author Marco Andreoli said in a press release.

The study suggests the early solar nebula may not have been as homogenous as we thought. "If Hypatia itself is not presolar, [some of its chemical] features indicate that the solar nebula wasn't the same kind of dust everywhere—which starts tugging at the generally accepted view of the formation of our solar system," Kramer said.

The researchers plan to further probe the rock's origins, hopefully solving some of the puzzles this study has presented.

[h/t Popular Mechanics]

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