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Everything You Need to Know About the Aug. 21 Eclipse
On Aug. 21, all of North America will experience a solar eclipse.
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.
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.
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.
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.
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.
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.
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.
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
How to Safely Watch the Aug. 21 Solar Eclipse
On Aug. 21, 2017, a solar eclipse will be visible in North America. Throughout the continent, the Moon will cover part – or all – of the Sun’s super-bright face for part of the day.
Since it’s never safe to look at the partially eclipsed or uneclipsed Sun, everyone who plans to watch the eclipse needs a plan to watch it safely. One of the easiest ways to watch an eclipse is solar viewing glasses – but there are a few things to check to make sure your glasses are safe:
Glasses should have an ISO 12312-2 certification
They should also have the manufacturer’s name and address, and you can check if the manufacturer has been verified by the American Astronomical Society
Make sure they have no scratches or damage
To use solar viewing glasses, make sure you put them on before looking up at the Sun, and look away before you remove them. Proper solar viewing glasses are extremely dark, and the landscape around you will be totally black when you put them on – all you should see is the Sun (and maybe some types of extremely bright lights if you have them nearby).
Never use solar viewing glasses while looking through a telescope, binoculars, camera viewfinder, or any other optical device. The concentrated solar rays will damage the filter and enter your eyes, causing serious injury. But you can use solar viewing glasses on top of your regular eyeglasses, if you use them!
If you don’t have solar viewing glasses, there are still ways to watch, like making your own pinhole projector. You can make a handheld box projector with just a few simple supplies – or simply hold any object with a small hole (like a piece of cardstock with a pinhole, or even a colander) above a piece of paper on the ground to project tiny images of the Sun.
Of course, you can also watch the entire eclipse online with us. Tune into nasa.gov/eclipselive starting at noon ET on Aug. 21!
For people 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.
You can look up the length of the total eclipse in your area to help you set a time for the appropriate length of time. Remember – this only applies to people within the path of totality.
Everyone else will need to use eclipse glasses or indirect viewing throughout the entire eclipse!
Photographing the Eclipse
Whether you’re an amateur photographer or a selfie master, try out these tips for photographing the eclipse.
#1 — Safety first: Make sure you have the required solar filter to protect your camera.
#2 — Any camera is a good camera, whether it’s a high-end DSLR or a camera phone – a good eye and vision for the image you want to create is most important.
#3 — Look up, down, and all around. As the Moon slips in front of the Sun, the landscape will be bathed in long shadows, creating eerie lighting across the landscape. Light filtering through the overlapping leaves of trees, which creates natural pinholes, will also project mini eclipse replicas on the ground. Everywhere you can point your camera can yield exceptional imagery, so be sure to compose some wide-angle photos that can capture your eclipse experience.
#4 — Practice: Be sure you know the capabilities of your camera before Eclipse Day. Most cameras, and even many camera phones, have adjustable exposures, which can help you darken or lighten your image during the tricky eclipse lighting. Make sure you know how to manually focus the camera for crisp shots.
#5 —Upload your eclipse images to NASA’s Eclipse Flickr Gallery and relive the eclipse through other peoples’ images.
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
Five Eclipses in NASA History
On Monday, August 21, 2017, people in North America will have the chance to see an eclipse of the Sun. Anyone within the path of totality may see one of nature’s most awe-inspiring sights – a total solar eclipse.
Along this path, the Moon will completely cover the Sun, revealing the Sun’s tenuous atmosphere, the corona. The path of totality will stretch from Salem, Oregon, to Charleston, South Carolina. Observers outside this path will still see a partial solar eclipse, where the Moon covers part of the Sun’s disk. Remember: you can never look at the Sun directly, and an eclipse is no exception – be sure to use a solar filter or indirect viewing method to watch partial phases of the eclipse.
Total solar eclipses are a rare chance to study the Sun and Earth in unique ways. During the total eclipse, scientists can observe the faintest regions of the Sun, as well as study the Sun’s effects on Earth’s upper atmosphere. We’ve been using eclipses to learn more about our solar system for more than 50 years. Let’s take a look back at five notable eclipses of the past five decades.
May 30, 1965
A total eclipse crossed the Pacific Ocean on May 30, 1965, starting near the northern tip of New Zealand and ending in Peru. Totality – when the Moon blocks all of the Sun’s face – lasted for 5 minutes and 15 seconds at peak, making this the 3rd-longest solar eclipse totality in the 20th century. Mexico and parts of the Southwestern United States saw a partial solar eclipse, meaning the Moon only blocked part of the Sun. We sent scientists to the path of totality, stationing researchers on South Pacific islands to study the response of the upper atmosphere and ionosphere to the eclipse.
Additionally, our high-flying jets, scientific balloons, and sounding rockets – suborbital research rockets that fly and collect data for only a few minutes – recorded data in different parts of the atmosphere. A Convair 990 research jet chased the Moon’s shadow as it crossed Earth’s surface, extending totality up to more than nine minutes, and giving scientists aboard more time to collect data. A NASA-funded team of researchers will use the same tactic with two jets to extend totality to more than 7 minutes on Aug. 21, 2017, up from the 2 minutes and 40 seconds observable on the ground.
March 7, 1970
The total solar eclipse of March 7, 1970, was visible in North America and the northwestern part of South America, with totality stretching to 3 minutes and 28 seconds at maximum. This was the first time a total eclipse in the United States passed over a permanent rocket launch facility – NASA’s Wallops Station (now Wallops Flight Facility) on the coast of Virginia. This eclipse offered scientists from NASA, four universities and seven other research organizations a unique way to conduct meteorology, ionospheric and solar physics experiments using 32 sounding rockets.
Also during this eclipse, the Space Electric Propulsion Test, or SERT, mission temporarily shut down because of the lack of sunlight. The experimental spacecraft was unable to restart for two days.
July 10, 1972
Two years later, North America saw another total solar eclipse. This time, totality lasted 2 minutes and 36 seconds at the longest. A pair of scientists from Marshall Space Flight Center in Huntsville, Alabama, traveled to the Canadian tundra to study the eclipse – specifically, a phenomenon called shadow bands. These are among the most ephemeral phenomena that observers see during the few minutes before and after a total solar eclipse. They appear as a multitude of faint rapidly moving bands that can be seen against a white background, such as a large piece of paper on the ground.
While the details of what causes the bands are not completely understood, the simplest explanation is that they arise from atmospheric turbulence. When light rays pass through eddies in the atmosphere, they are refracted, creating shadow bands.
February 26, 1979
The last total solar eclipse of the 20th century in the contiguous United States was in early 1979. Totality lasted for a maximum of 2 minutes 49 seconds, and the total eclipse was visible on a narrow path stretching from the Pacific Northwest to Greenland. Agencies from Canada and the United States – including NASA – joined forces to build a sounding rocket program to study the atmosphere and ionosphere during the eclipse by observing particles on the edge of space as the Sun’s radiation was suddenly blocked.
July 31, 1981
The USSR got a great view of the Moon passing in front of the Sun in the summer of 1981, with totality lasting just over 2 minutes at maximum. Our scientists partnered with Hawaiian and British researchers to study the Sun’s atmosphere – specifically, a relatively thin region called the chromosphere, which is sandwiched between the Sun’s visible surface and the corona – using an infrared telescope aboard the Kuiper Airborne Observatory. The chromosphere appears as the red rim of the solar disk during a total solar eclipse, whereas the corona has no discernible color to the naked eye.
Watch an Eclipse: August 21, 2017
On August 21, a total solar eclipse will cross the continental United States from coast to coast for the first time in 99 years, and you can watch.
If skies are clear, people in North America will be able to see a partial or total solar eclipse. Find out what the eclipse will look like in your area, then make sure you have a safe method to watch – like solar viewing glasses or a pinhole projector – and head outside.
You can also tune into nasa.gov/eclipselive throughout the day on Aug. 21 to see the eclipse like you’ve never seen it before – including a NASA TV show, views from our spacecraft, aircraft, and more than 50 high-altitude balloons.
Get all your eclipse information at https://eclipse2017.nasa.gov/, and follow along with @NASASun on Twitter and NASA Sun Science on Facebook.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com