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larEclipse

Solar eclipses happen because of a fantastic cosmic coincidence. From our vantage point here on Globe, the Dominicus is nigh 400 times larger in bore than the Moon. But the Moon is besides about 400 times closer than the Dominicus. Because of this, the Lord's day and the Moon appear to exist about the same size in our sky. This is what makes a total solar eclipse possible.

As a result, nosotros on Globe's surface get to see the Moon cover the sun completely, only leave its temper — the corona — visible to our unprotected optics during those precious few moments of totality. (ExtremeTech STRONGLY recommends that no one endeavour to view an eclipse without appropriate eye protection -Ed).

Today's eclipse is a full solar eclipse along its path of totality, and a partial solar eclipse in every other place it tin can be seen in Northward America. On the ground, people nether the path of totality get to see some remarkable things, which we've rounded up beneath. Equally always, each prototype can be clicked to open it in a new window:

How do we know when and where nosotros'll run into an eclipse?

Math! From the Babylonians until today, we've been using increasingly subtle math to calculate and predict the appearance of an eclipse. Aboriginal astronomers had no idea what an eclipse was, but they identified them every bit unusual occurences of enormous significance. An eclipse was typically viewed equally a very bad omen, and a sign that the gods were aroused with mortal men. In at least ane instance, however, an eclipse is credited with stopping a state of war between the Lydians and the Medes. Herotodus writes:

Every bit, all the same, the balance had not inclined in favour of either nation, another combat took identify in the sixth year, in the grade of which, just as the battle was growing warm, day was on a sudden changed into nighttime. This consequence had been foretold by Thales, the Milesian, who forewarned the Ionians of it, fixing for information technology the very year in which it actually took identify. The Medes and Lydians, when they observed the modify, ceased fighting, and were alike anxious to have terms of peace agreed on.

It is not known if this eclipse really occurred or if it occurred in the manner described, only it'southward a unique attribution to an eclipse in whatever case. More data on what ancient civilizations knew almost eclipses is available here.

Over the millennia, we've learned a not bad deal about the Sun from studying various eclipses, including:

968: The get-go clear clarification of the sun's corona during a solar eclipse was written by a chronicler in Constantinople.

1687: Newton publishes his Principia. For the first time, it becomes possible to predict eclipses accurately over long periods of time.

1715: Edmund Halley reports the phenomenon that would later be known every bit Baily'southward Beads (discussed in the slideshow above). Haley also draws a map of the eclipse's visibility across England.

1724: Jose Joaquin de Ferrer observes and names the corona, after observing it in a total eclipse. He also posits that it must vest to the sun rather than the moon, due to its overall size.

1868: The element of helium is detected through ascertainment of a solar eclipse. Originally thought to be sodium, further research demonstrated that information technology was an chemical element equally-all the same unkown on Earth. It'southward named "helium" for Helios, the Greek god of the Dominicus.

1887: Proving that eclipses can be studied with balloons, Russian astronomer Dmitry Ivanovich Mendeleev ascends to xi,500 feet to observe an eclipse in a higher place the cloud cover. NASA afterward copies his thought in 2022 (no, not really).

1919: William Wallace Campbell and Robert Trumpler confirm Einstein's general theory of relativity by observing the relativistic bending of starlight around the lord's day during an eclipse.

1973: Scientists use a Concorde prototype to extend the duration of a solar eclipse by 10x, spending well over an hour in the path of totality (74 minutes).

What's NASA doing during the eclipse?

NASA has a ton of science experiments fix for the narrow concrete and temporal window of the eclipse. Amongst others, the crew of the ISS will be watching the eclipse too; they should become to run across a fractional eclipse, and they as well go to spotter the moon'south shadow travel across the Earth's surface from above. They're doing an astrobiological experiment using leaner sent aloft with balloons to study how terrestrial leaner might answer to Mars-like weather condition.

"The solar eclipse over the continental U.s. gives us a rare opportunity to written report the stratosphere when it is even more than Mars-similar. Ordinarily, stratospheric UVA & UVB are slightly higher than the surface of Mars. With the total solar eclipse on Aug. 21 and most 55 teams flying balloon payloads across 33 states at various points along the path of totality, we await to obtain a modulated sunlight slope in the upper atmosphere, more closely resembling Mars UVA & UVB levels. This will provide a loftier-allegiance analog surround, only available for a few hours, for studying microbial responses to Mars atmospheric condition," NASA wrote in its 2022 Eclipse press kit (PDF).

ballon_launch_eclipse_map

A NASA infographic with details one of its balloon experiments.

"Moreover, it is well-nigh inconceivable to perform a standardized, coordinated astrobiology experiment beyond 33 states simultaneously. The eclipse project offers a special opportunity for high statistical fidelity and extremely wide spatial coverage in the stratosphere."

eclipse_epc_2016068_4

NASA's Deep Infinite Climate Observatory (DSCOVR) will be in position to view the 2022 eclipse, the same way it observed the 2022 eclipse. The photo above is from that ascertainment menstruum.

NASA approved a multifariousness of studies and investigations that focus on both the dominicus and the Earth. The University of Hawaii will exist measuring the physics of coronal plasma, the University Corporation for Atmospheric Enquiry volition mensurate the infared solar corona, MIT volition investigate how the solar eclipse changes the ionosphere over the continental United States, and DISCOVR and NISTAR will collaborate to perform a "three-D radiative transfer closure experiment." A total list of experiments is available hither.

Enjoy the show, anybody! Wear your glasses, don't take stupid risks, and stay condom.