The Mental Floss Field Guide to Viewing the Solar Eclipse

A total solar eclipse will cross the United States on August 21, 2017, and if you want to catch it, you'll probably want to start making preparations now. To see the total eclipse (which you really want to do!), you will need to travel to the path of totality. Mental Floss spoke to Mitzi Adams, a heliophysicist at NASA Marshall Space Flight Center, about everything you need to know to see the Sun disappear, photograph the process, why it's important to scientists, and how cultures around the world have interpreted the celestial phenomenon.

WHAT AM I LOOKING FOR DURING THE ECLIPSE?

The total solar eclipse is made up of phases. First, there's first contact, when the Sun and Moon first "touch." This leads into the partial phase, when it looks like someone is taking increasingly large bites from the Sun. Next is the actual eclipse itself, when the Sun is totally covered by the Moon. It lasts a very brief time, from a few seconds to just over two minutes, depending on where along the path you view it. The Sun passes through partial phases again as the Moon continues on its way. During the total phase, remove your eclipse eyewear and behold the corona of the Sun, wispy, revenant limbs of light reaching from a black hole in the sky. Stars and planets will be visible as day has turned to an eerie, ethereal night.

Down on the Earth's surface, says Adams, you'll notice that nature has no idea what's going on. "During the total phase when the light from the Sun's photosphere is completely blocked, some animals react," she tells Mental Floss. "The cows may start walking toward the barn. Horses may do the same. Crickets start chirping. You'll hear frogs. Birds will go to roost. Chickens will react the same way they do at sunset. All animals, including the human ones, react to eclipses in some way. The human reaction is typically, 'Wow! Look at that!'"

WHAT TOOLS CAN I USE TO VIEW AN ECLIPSE (WITHOUT GOING BLIND)?

During the partial phase of a total eclipse, you need to wear special eclipse glasses that protect your eyes from the Sun. This isn't some overly cautious government recommendation that only the squares follow. If you don't wear the glasses, you won't be able to see anything that's happening because you are staring at the Sun. Eclipse glasses can be found online, at public libraries and museums, and, along the path of totality, science advocacy and public education initiatives should have glasses freely available in large quantities. By the time the eclipse gets here, if you can't find glasses, it's because you didn't want to find them.

If you want to up your game, though, the Bill Nye Solar Eclipse Glasses might soon be the It-item of Milan's runways. Described as featuring a "stylish frame that is fashionable for both men and women" (complete with a silhouette of Nye's face on one of the arms), these glasses are "built to last"—and they would have to be. It will be seven years before the next total solar eclipse over North America.

Eclipse glasses will not magnify the eclipse. You can, however, use a telescope or pair of binoculars if you want to get a closer look. You really need to know what you're doing, though, and if this is your first eclipse, ask yourself if it is worth fiddling with knobs during what might be a once-in-a-lifetime event. If you're going to use a telescope, though, here's some advice from the heliophysicist:

"The safest way is to have a special filter that will fit over the front of the telescope," says Adams. "The telescope could be a refractor or a reflector. Binoculars would also work, though you want either two filters, or one filter while you block the light over one side of the binocular pair. Any of these filters will fit over the front."

The filters will be made of mylar or glass, she says, and warns that they must be specifically certified as safe for viewing the Sun. "You do not want to use any kind of filter that will screw into an eyepiece because they will crack, and it doesn't take very long—just a couple of seconds—to build up the heat to crack the filter."

If you want to view the Sun up close during the partial phase of the eclipse, be on the lookout for sunspots, the darker areas seen on the surface of the Sun. The current phase of the Sunspot cycles suggests that there won't be any Sunspots large enough to see with the naked eye. With a telescope, though, you might have better luck.

WHEN NASA LOOKS AT THE SUN, WHAT ARE THEY LOOKING FOR?

"We want to learn as much about Sun as possible," says Adams. "We're trying to study from the core of Sun all the way out to the corona, which is the outer layer of the Sun's atmosphere. The eclipse will enable us to study the inner corona. We can actually build pictures of events on Sun from the photosphere, through the chromosphere, and into the corona."

Scientists will combine the visible light images that they get from the eclipse with images from sources such as NASA's Solar Dynamics Observatory in orbit around the Earth. The observatory views the Sun in multiple wavelengths—mostly extreme ultraviolet—continuously, but it is unable to get the inner corona in visible light. "We can't really study the full spectrum unless we're using images from a solar eclipse," says Adams.

HOW DO I PHOTOGRAPH THE ECLIPSE?

Nikon has provided a comprehensive guide to photographing the Sun both conventionally, on a tripod, and with a special telescope mount. Eclipse2017 also has a useful set of pointers for how to preserve the moment. But the big thing to remember is, DO NOT USE A FLASH—not for reasons related to photography (though seriously, do you think your Galaxy S6 flash is strong enough illuminate the entire sky?) but because part of the wonder of the event is the day turning to night! Light pollution is already a problem for skywatching. Don't turn the eclipse into a light toxic waste dump. (Do not use a flashlight, either.) The best photography advice might be to keep your camera at home and enjoy the total eclipse with your eyes—not through a glass screen.

CAN I HELP DO SCIENCE?

Yes, and the American Astronomical Society has you covered. There's Citizen CATE, in which amateur astronomers across the country will use identical cameras and telescope equipment to take pictures of the Sun's inner corona; the Do-It-Yourself Relativity Test, in which, during the eclipse, you can "measure the gravitational deflection of starlight and prove for yourself that Einstein really was right" with no special equipment; the Eclipse Megamovie Project, which will use images and footage taken of the eclipse by citizen scientists across the country, and, from that, stitch together a high-definition video of the eclipse; and there are many, many others.

WILL TRAVEL BE A PROBLEM?

Yep! Finding a hotel room will be a problem. Entrepreneurial members of Airbnb who live along the path of totality are renting out square footage in their yards for people to set up tents, and they're charging hundreds of dollars for the favor. Your best bet for finding a reasonably priced room is Nashville, which is the largest city on the path and a major tourist destination year-round. Traffic will be a problem, though nobody knows how bad, exactly, because it's been 38 years since an eclipse path of totality passed over the continental United States, and nearly 100 since the last coast-to-coast eclipse. What you need to know is that 200 million people live within a day's drive (about 500 miles) of the path. It doesn't take a civil engineer to imagine how that might go. Parking will be a problem. Make sure your gas tank is full, you have food and water in the car, and for the love of all that is good and holy, insist that the kids try to use the bathroom before you get on the highway. It might be a very long, very slow drive even for short distances.

I HAVE KIDS—WHAT DO I DO WITH THEM?

Bring them! Most of the communities along the path of totality are pulling out all the stops. While you wait for the (very brief) show, there will be plenty of entertainment, and NASA will have beachhead presence across the country with science demonstrations for kids and adults alike. Just make sure everyone has their own pair of eclipse glasses.

THE ECLIPSE WILL NOT CHANGE THE SUN'S RAYS AND GIVE YOU CANCER.

There are a lot of mistaken beliefs about eclipses that should be put to rest. "One large misconception is that somehow going outside during the eclipse is dangerous—that there are somehow 'eclipse rays' that happen, and that the Sun is more dangerous during an eclipse," says Adams. "That's just not true. The light from the Sun is exactly the same from an eclipse as when it's not eclipsed."

Likewise, staring at an eclipse when it is at totality will not make you go blind. Indeed, during totality, that's when you take off your eclipse glasses and specifically stare at the Moon-concealed Sun.

WHAT GROUPS ARE CELEBRATING THE EVENT?

The entire U.S. will see at least 70 percent coverage of the Sun, which is pretty good when compared with the 0 percent coverage we get every day. As such, the whole country will evolve into one massive solar celebration, with literally thousands of parties and viewing events being held at schools, libraries, museums, parks, amateur astronomy groups, university astronomy departments—you name it, they're doing it. There are multi-day music festivals in Oregon and Illinois, the latter of which is called Moonstock, with Ozzy Osbourne headlining.

Even if you live outside the path of totality, NASA will help you host an eclipse party. They've even built an international map of experts that you can reach out to for party entertainment. (Ozzy Osbourne will not have useful astronomy advice, I can assure you. But Brian May, on the other hand … )

WHERE WILL HAVE THE BEST WEATHER FOR THE ECLIPSE?

The entire path of totality has a reasonable chance of good weather. For the very best weather in the country on eclipse day, Great American Eclipse says that Oregon is the place to be. "While the Oregon coast is at risk of marine clouds," they report, "the interior of this state actually enjoys the nation's best weather prospects." Snake River Valley, Idaho, and western Nebraska are also recommended for their extensive network of highways and farm roads. If clouds roll in, you can easily relocate to some place more favorable.

HOW HAVE CULTURES INTERPRETED ECLIPSES OVER THE CENTURIES?

Our friends at the Lunar and Planetary Institute have commissioned an extraordinary collection of multicultural eclipse folktales, performed by professional storytellers Cassandra Wye and Fran Stallings. The stories reveal how people around the world going back centuries have explained and interpreted eclipses, from the Batammaliba people of Africa, whose eclipse origin story sees the Moon taking revenge on the Sun, to the Anishabe people of North America, for whom the Sun was briefly imprisoned.

Could an Astronaut Steal a Rocket and Lift Off, Without Mission Control?

iStock
iStock

C Stuart Hardwick:

Not with any rocket that has ever thus far carried a person into orbit from Earth, no. Large rockets are complex, their launch facilities are complex, their trajectories are complex, and the production of their propellants is complex.

Let me give you one simple example:

  • Let’s say astro-Sally is the last woman on Earth, and is fully qualified to fly the Saturn-V.
  • Further, let’s say the Rapture (which as I understand it, is some sort of hip-hop induced global catastrophe that liquefies all the people) has left a Saturn-V sitting on the pad, raring to go.
  • Further, let’s grant that, given enough time, astro-Sally can locate sufficient documentation to operate the several dozen controls needed to pump the first stage propellant tanks full of kerosene.
  • Now what? Oxidizer, right? Wrong. First, she has to attend to the batteries, oxygen, hydrogen, and helium pressurant tanks in her spacecraft, otherwise it’s going to be a short, final flight. And she’ll need to fill the hypergolics for the spacecraft propulsion and maneuvering systems. If she screws that up, the rocket will explode with her crawling on it. If she gets a single drop of either of these on her skin or in her lungs, she’ll die.
  • But okay, maybe all the hypergolics were already loaded (not safe, but possible) and assume she manages to get the LOX, H2, and HE tanks ready without going Hindenburg all over the Cape.
  • And…let’s just say Hermione Granger comes back from the Rapture to work that obscure spell, propellantus preparum.
  • All set, right? Well, no. See, before any large rocket can lift off, the water quench system must be in operation. Lift off without it, and the sound pressure generated by the engines will bounce off the pad, cave in the first stage, and cause 36 stories of rocket to go “boom.”
  • So she searches the blockhouse and figures out how to turn on the water quench system, then hops in the director’s Tesla (why not?) and speeds out to the pad, jumps in the lift, starts up the gantry—and the water quench system runs out of water ... Where’d she think that water comes from? Fairies? No, it comes from a water tower—loaded with an ample supply for a couple of launch attempts. Then it must be refilled.

Now imagine how much harder this would all be with the FBI on your tail.

Can a rocket be built that’s simple enough and automated enough to be susceptible to theft? Sure. Have we done so? Nope. The Soyuz is probably the closest—being highly derived from an ICBM designed to be “easy” to launch, but even it’s really not very close.

This post originally appeared on Quora. Click here to view.

The Science Behind Why the Earth Isn't Flat

Earth as captured from near the lunar horizon by the Lunar Reconnaissance Orbiter in 2015.
Earth as captured from near the lunar horizon by the Lunar Reconnaissance Orbiter in 2015.
NASA

On March 24, 2018, flat-earther Mike Hughes set out prove that the Earth is shaped like a Frisbee. The plan: Strap himself to a homemade steam-powered rocket and launch 52 miles into sky above California’s Mojave Desert, where he'd see Earth's shape with his own eyes.

It didn't matter that astronauts like John Glenn and Neil Armstrong had been to space and verified that the Earth is round; Hughes didn't believe them. According to The Washington Post, Hughes thought they were "merely paid actors performing in front of a computer-generated image of a round globe."

The attempt, ultimately, was a flop. He fell back to Earth with minor injuries after reaching 1875 feet—not even as high as the tip of One World Trade Center. For the cost of his rocket stunt ($20,000), Hughes could have easily flown around the world on a commercial airliner at 35,000 feet.

Hughes isn't alone in his misguided belief: Remarkably, thousands of years after the ancient Greeks proved our planet is a sphere, the flat-Earth movement seems to be gaining momentum. "Theories" abound on YouTube, and the flat-Earth Facebook page has some 194,000 followers.

Of course, the Earth isn't flat. It's a sphere. There is zero doubt about this fact in the real, round world. To say the evidence is overwhelming is an understatement.

HOT SPINNING BODIES

Not every celestial body is a sphere, but round objects are common in the universe: In addition to Earth and all other known large planets, stars and bigger moons are also ball-shaped. These objects, and billions of others, have the same shape because of gravity, which pulls everything toward everything else. All of that pulling makes an object as compact as it can be, and nothing is more compact than a sphere. Say, for example, you have a sphere of modeling clay that is exactly 10 inches in diameter. No part of the mass is more than 5 inches from the center. That's not the case with any other shape—some part of the material will be more than 5 inches from the center of the mass. A sphere is the smallest option.

Today the Earth is mostly solid with a liquid outer core, but when the planet was forming, some 4.5 billion years ago, it was very hot and behaved like more like a fluid—and was subject to the squishing effects of gravity.

And yet, the Earth isn't a perfect sphere; it bulges slightly at the equator. "Over a long time-scale, the Earth acts like a highly viscous fluid," says Surendra Adhikari, a geophysicist at the Jet Propulsion Laboratory in Pasadena, California. The Earth has been spinning since it was formed, and "if you have a spinning fluid, it will bulge out due to centrifugal forces." You can see evidence for this at the equator, where the Earth's diameter is 7926 miles—27 miles larger than at the poles (7899 miles). The difference is tiny—just one-third of 1 percent.

THE SHADOW KNOWS

The ancient Greeks figured out that Earth was a sphere 2300 years ago by observing the planet's curved shadow during a lunar eclipse, when the Earth passes between the Sun and the Moon. Some flat-Earth believers claim the world is shaped like a disk, perhaps with a wall of ice along the outer rim. (Why no one has ever seen this supposed wall, let alone crashed into it, remains unexplained.) Wouldn't a disk-shaped Earth also cast a round shadow? Well, it would depend on the orientation of the disk. If sunlight just happened to hit the disk face-on, it would have a round shadow. But if light hit the disk edge-on, the shadow would be a thin, straight line. And if the light fell at an oblique angle, the shadow would be a football–shaped ellipse. We know the Earth is spinning, so it can't present one side toward the Sun time after time. What we observe during lunar eclipses is that the planet's shadow is always round, so its shape has to be spherical.

The ancient Greeks also knew Earth's size, which they determined using the Earth's shape. In the 2nd century BCE, a thinker named Eratosthenes read that on a certain day, the people of Syene, in southern Egypt, reported seeing the Sun directly overhead at noon. But in Alexandria, in northern Egypt, on that same day at the same time, Eratosthenes had observed the Sun being several degrees away from overhead. If the Earth were flat, that would be impossible: The Sun would have to be the same height in the sky for observers everywhere, at each moment in time. By measuring the size of this angle, and knowing the distance between the two cities, Eratosthenes was able to calculate the Earth's diameter, coming up with a value within about 15 percent of the modern figure.

And when Columbus set sail from Spain in 1492, the question wasn't "Would he fall off the edge of the world?"—educated people knew the Earth was round—but rather, how long a westward voyage from Europe to Asia would take, and whether any new continents might be found along the way. During the Age of Exploration, European sailors noticed that, as they sailed south, "new" constellations came into view—stars that could never be seen from their home latitudes. If the world were flat, the same constellations would be visible from everywhere on the Earth's surface.

Finally, in 1522, Ferdinand Magellan's crew became the first people to circle the globe. Like Columbus, Magellan also set off from Spain, in 1519, heading west—and kept generally going west for the next three years. The expedition wound up back at the starting point (though without Magellan, who was killed during a battle in the Philippines). And speaking of ships and seafaring: One only needs to watch a tall ship sailing away from port to see that its hull disappears before the top of its mast. That happens because the ship is traveling along a curved surface; if the Earth were flat, the ship would just appear smaller and smaller, without any part of it slipping below the horizon.

THE EVIDENCE IS ALL AROUND (AND ALL ROUND)

But you don't need a ship to verify the Earth's shape. When the Sun is rising in, say, Moscow, it's setting in Los Angeles; when it's the middle of the night in New Delhi, the Sun is shining high in the sky in Chicago. These differences occur because the globe is constantly spinning, completing one revolution per day. If the Earth were flat, it would be daytime everywhere at once, followed by nighttime everywhere at once.

You also experience the Earth's roundness every time you take a long-distance flight. Jetliners fly along the shortest path between any two cities. "We use flight paths that are calculated on the basis of the Earth being round," Adhikari says. Imagine a flight from New York to Sydney: It would typically head northwest, toward Alaska, then southwest toward Australia. On the map provided in your airline's in-flight magazine, that might look like a peculiar path. But wrap a piece of string around a globe, and you'll see that it’s the shortest possible route.

"If the Earth were flat," Adhikari says, "the trajectory would be completely different." How different depends on which way the globe is sliced into a flattened map, but if it looked like it does on a Mercator-projection map, it might head east and pass over Africa.

Engineers and architects also take the Earth's curvature into account when building large structures. A good example is the towers that support long suspension bridges such as the Verrazano Narrows bridge in New York City. Its towers are slightly out of parallel with each other, the tops being more than 1.5 inches further apart than their bases. If the Earth were flat, the bottom of the towers would be separated by the exact same distance as the top of the towers; the planet's curvature forces the tops of the towers apart.

And for the last half-century, we've had eyewitness and photographic proof of the Earth's shape. In December 1968, the crew of Apollo 8 left Earth for the Moon. When they looked out of the Command Module windows, they saw a blue-and-white marble suspended against the blackness of space. On Christmas Eve, lunar module pilot William Anders snapped the famous "Earthrise" photograph. It gave us an awe-inspiring perspective of our round planet that was unprecedented in human history—but it wasn't a surprise to anyone.

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios