Everything You Need to Know About the Aug. 21 Eclipse

On Aug. 21, all of North America will experience a solar eclipse.

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If skies are clear, eclipse-watchers will be able to see a partial solar eclipse over several hours, and some people – within the narrow path of totality – will see a total solar eclipse for a few moments.

How to Watch

It’s never safe to look at the Sun, and an eclipse is no exception. During a partial eclipse (or on any regular day) you must use special solar filters or an indirect viewing method to watch the Sun.

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If you have solar viewing glasses, check to make sure they’re safe and undamaged before using them to look at the Sun. Make sure you put them on before looking up at the Sun, and look away before removing them. Eclipse glasses can be used over your regular eyeglasses, but they should never be used when looking through telescopes, binoculars, camera viewfinders, or any other optical device.

If you don’t have eclipse glasses, you can still watch the eclipse indirectly! You can make a pinhole projector out of a box, or use any other object with tiny holes – like a piece of cardstock with a hole, or your outstretched, interlaced fingers – to project an image of the partially eclipsed Sun onto the ground.

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Of course, if it’s cloudy (or you’d just rather stay inside), you can watch the whole thing online with us at nasa.gov/eclipselive. Tune in starting at noon ET.

If you’re in the path of totality, there will be a few brief moments when it is safe to look directly at the eclipse. Only once the Moon has completely covered the Sun and there is no light shining through is it safe to look at the eclipse. Make sure you put your eclipse glasses back on or return to indirect viewing before the first flash of sunlight appears around the Moon’s edge.

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Why do eclipses happen?

A solar eclipse happens when the Moon passes directly between the Sun and Earth, casting its shadow down on Earth’s surface. The path of totality – where the Moon completely covers the Sun – is traced out by the Moon’s inner shadow, the umbra. People within the Moon’s outer shadow, the penumbra, can see a partial eclipse.

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The Moon’s orbit around Earth is tilted by about five degrees, meaning that its shadow usually doesn’t fall on Earth. Only when the Moon lines up exactly between the Sun and Earth do we see an eclipse.

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Though the Sun is about 400 times wider than the Moon, it is also about 400 times farther away, making their apparent sizes match up almost exactly. This is what allows the Moon to block out the Sun’s bright face, while revealing the comparatively faint, pearly-white corona.

The Science of Eclipses

Eclipses are a beautiful sight to see, and they’re also helpful for our scientists, so we’re funding eleven ground-based science investigations to learn more about the Sun and Earth.

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Total solar eclipses reveal the innermost regions of the Sun’s atmosphere, the corona. Though it’s thought to house the processes that kick-start much of the space weather that can influence Earth, as well as heating the whole corona to extraordinarily high temperatures, we can’t study this region at any other time. This is because coronagraphs – the instruments we use to study the Sun’s atmosphere by creating artificial eclipses – must cover up much of the corona, as well as the Sun’s face in order to produce clear images.

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Eclipses also give us the chance to study Earth’s atmosphere under uncommon conditions: the sudden loss of solar radiation from within the Moon’s shadow. We’ll be studying the responses of both Earth’s ionosphere – the region of charged particles in the upper atmosphere – and the lower atmosphere.

Learn all about the Aug. 21 eclipse at eclipse2017.nasa.gov, and follow @NASASun on Twitter and NASA Sun Science on Facebook for more. Watch the eclipse through the eyes of NASA at nasa.gov/eclipselive starting at 12 PM ET on Aug. 21. 

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

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On Monday, August 21, 2017, our nation will be treated to a…

On Monday, August 21, 2017, our nation will be treated to a total eclipse of the Sun. The eclipse will be visible – weather permitting – across all of North America. The entire continent will experience at least a partial eclipse lasting two to three hours. Halfway through the event, anyone within a 60 to 70 mile-wide path from Oregon to South Carolina will experience a total eclipse. During those brief moments when the moon completely blocks the Sun’s bright face for 2+ minutes, day will turn into night, making visible the otherwise hidden solar corona, the Sun’s outer atmosphere. Bright stars and planets will become visible as well. This is truly one of nature’s most awesome sights. The eclipse provides a unique opportunity to study the Sun, Earth, Moon and their interaction because of the eclipse’s long path over land coast to coast.

Scientists will be able to take ground-based and airborne observations over a period of about 90 minutes to complement the wealth of data provided by NASA assets.

Watch this and other eclipse videos on our YouTube channel: https://youtu.be/8jaxiha8-rY?list=PL_8hVmWnP_O2oVpjXjd_5De4EalioxAUi

To learn all about the 2017 Total Eclipse: https://eclipse2017.nasa.gov/

Music credit: Ascending Lanterns by Philip Hochstrate

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

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The Great Aviation Transformation Begins

On this National Aviation Day, we’re going “X.” 

Today we celebrate the birthday of one of America’s original U.S. aviation pioneers — Orville Wright. But this year we also celebrate the pioneers of right now — the women and men of NASA who are changing the face of aviation by going “X.” We’re starting the design and build of a series of piloted experimental aircraft – X-planes – for the final proof that new advanced tech and revolutionary shapes will give us faster, quieter, cleaner ways to get from here to there.

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So, what is an X-plane?

Since the early days of aviation, X-planes have been used to demonstrate new technologies in their native environment – flying through the air aboard an aircraft that’s shaped differently from the tube-and-wing of today. X-planes are the final step after ground tests. They provide valuable data that can lead to changes in regulation, design, operations, and options for travel. Two of the most famous historical X-planes are the Bell X-1 and the X-15.

Why can’t I fly supersonic now, say from New York to Seattle?

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Because of the loud, jarring sonic boom. Commercial supersonic flight over land and, therefore over communities, is currently prohibited. Our supersonic X-plane will fly “quiet”; there’ll still be a sonic boom but it’ll sound more like a soft “thump.”  The Low Boom Flight Demonstration X-plane, scheduled for first flight in 2021 and to begin community overflight testing in 2022, will provide the technical and human response data to federal and international regulators so they can consider lifting the ban. If that happens, someday commercial supersonic passenger flights between U.S. coasts would be less than three hours.

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This is a preliminary design of the Low Boom Flight Demonstration X-plane. Its shape is carefully tailored to prevent the formation of a loud sonic boom.

Will I ever be able to carry on a conversation when a plane flies overhead?

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Yes. Our next X-plane will be one that flies at regular speed, but has advanced design technologies and a nontraditional shape that drop perceived noise level by more than half. It will also reduce fuel consumption by 60-80 percent, and cut emissions by more than 80 percent. Design of this piloted X-plane is expected to begin around 2020.

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This possible X-plane design is a blended wing body, which reduces drag and increases lift, and also reduces noise because the engines are placed above the fuselage.

Will I ever fly on an airplane powered like my Prius?

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Probably. All- or hybrid-electric aircraft that can carry 12 – 120 passengers are becoming more likely. For a larger aircraft and possible future X-plane, NASA is studying how to use electric power generated by the engines to drive a large fan in a tail-cone and get additional thrust for takeoff and reduce fuel use.

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This possible future subsonic X-plane would use electricity to power a large fan in the tail-cone, providing extra thrust at takeoff.

We – along with our government, industry and academic partners – have begun the great aviation transformation. And you’ll witness every important moment of our X-plane stories, here and on every #NationalAviationDay.

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Like the X-plane posters for National Aviation Day? Download them: https://www.nasa.gov/aero/nasa-x/

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