Technology What Solar Eclipses Have Taught Us About the Universe

16:51  13 august  2017
16:51  13 august  2017 Source:   Time

Eclipse-chasers trot the globe, addicted to Moon's shadow

  Eclipse-chasers trot the globe, addicted to Moon's shadow Eclipse-chasers are a dedicated crew of scientists who travel the globe to catch a few moments in eerie darkness, and even after seeing dozens of eclipses, they say they can't get enough.Also known as "umbraphiles," these self-described addicts live their lives in pursuit of the intense experience of falling under the Moon's shadow.

Total solar eclipses like the one that will cross the US on August 21 have taught us about how the universe works. 21 have captured the attention of astronomers throughout history — and have often led to advances in our understanding of how the universe works.

What 4,000 Years of Solar Eclipses Taught Us About the Universe . For millennia, humans have used solar eclipses to learn about the universe . We are still learning. More From Solar Eclipse 2017. 12 articles. What We Will Learn During August's Solar Eclipse .

A total solar eclipse can be seen in Svalbard, Longyearbyen, Norway, on March 20, 2015. A partial eclipse of varying degrees is visible, depending on weather conditions, across most of Europe, northern Africa, northwest Asia and the Middle East, before finishing its show close to the North Pole. AFP PHOTO / NTB SCANPIX / JON OLAV NESVOLD +++ NORWAY OUT (Photo credit should read JON OLAV NESVOLD/AFP/Getty Images)© JON OLAV NESVOLD—AFP/Getty Images A total solar eclipse can be seen in Svalbard, Longyearbyen, Norway, on March 20, 2015. A partial eclipse of varying degrees is visible, depending on weather conditions, across most of Europe, northern Africa, northwest Asia and the Middle East, before finishing its show close to the North Pole. AFP PHOTO / NTB SCANPIX / JON OLAV NESVOLD +++ NORWAY OUT (Photo credit should read JON OLAV NESVOLD/AFP/Getty Images)

Total solar eclipses like the one that will cross the U.S. on Aug. 21 have captured the attention of astronomers throughout history — and have often led to advances in our understanding of how the universe works.

If you're watching the total solar eclipse, don't forget to wear sunscreen

  If you're watching the total solar eclipse, don't forget to wear sunscreen Be sure to wear sunscreen — especially if you're planning to view it for a long time. While you might be more concerned with keeping your eyes safe from the sun, the hour or two you spend watching the whole process will leave your skin exposed.

Total solar eclipses like the one that will cross the U . S . on Aug. 21 have captured the attention of astronomers throughout history — and have often led to advances in our understanding of how the universe works.

Total solar eclipses like the one that will cross the U . S . on Aug. 21 have captured the attention of astronomers throughout history — and have often led to advances in our understanding of how the universe works.

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Astronomers have been studying solar eclipses for centuries. In the late 16th and early 17th centuries, Danish astronomer Tycho Brahe and his apprentice German astronomer Johannes Kepler studied eclipses to try to arrive at a rough estimate of the moon’s diameter.

In the 19th century, eclipse observations got even more interesting, thanks in large part to advances in scientific instruments like telescopes and spectrometers, devices that let scientists analyze the chemistry of stars and distant planets. In 1868, French astronomer Jules Janssen and English astronomer Norman Lockyer were observing separate solar eclipses when they discovered a new element, which they named helios, after the Greek word for “sun.” Today, it’s known as helium.

What Is a Partial Solar Eclipse?

  What Is a Partial Solar Eclipse? A total solar eclipse will stretch across the U.S. on Aug. 21, giving people in parts of 14 states the chance to see one of the great celestial events we can witness on Earth. But outside the path of totality, in which people will see the moon entirely block the sun, the rest of America will witness an event that is not quite as grand but is still impressive: a partial solar eclipse. Here’s what you need to know about it:What is a partial eclipse?A partial eclipse occurs when the moon passes almost directly between the sun and the Earth.

Links about solar eclipses . Other myths about the Sun. Shop Windows to the Universe Science Store! Cool It! is the new card game from the Union of Concerned Scientists that teaches kids about the choices we have when it comes to climate change—and how policy and technology decisions

This is a diagram of a typical solar eclipse . During a total solar eclipse , the umbra reaches the Earth. During an annular eclipse , it does not. Shop Windows to the Universe Science Store! Cool It! is the new card game from the Union of Concerned Scientists that teaches kids about the choices we have

During an eclipse in 1879, American astronomer Charles Augustus Young and Scotland-born astronomer William Harkness both thought they had discovered another new element. But they had actually observed exceptionally hot iron in the sun’s corona, the sun’s outer atmosphere. This was the first indication that the corona is millions of degrees hotter than the sun’s surface, a mystery that puzzles astronomers to this day.

Perhaps the most interesting eclipse-based discovery came in 1919. Albert Einstein’s theory of general relativity was still being met with skepticism. Under this theory, big gravitational masses like stars and planets warp the fabric of space-time, bending light as it travels through the universe. Einstein didn’t have a way of proving it, but luckily, Sir Frank Watson Dyson, the Astronomer Royal of Britain at the time, a senior post in the Royal Households of the U.K., came up with a solution. He plotted the positions of stars that would be near the sun’s limb, or edge, before a solar eclipse, then measured their positions again during the eclipse. He found that the stars’ positions had changed. The only explanation was that the mass of the sun was bending space-time and curving the stars’ light. They looked to be in different positions, but it was really an effect of the sun’s mass. It was proof Einstein was right.

So when you watch the eclipse on Aug. 21, which will be visible in parts of 14 states as a total solar solar eclipse and in the rest of the country as a partial solar eclipse, it’s a good moment to remember the cosmic event’s history of illuminating our place in space.

Amy Shira Teitel is a spaceflight historian who will co-host TIME’s livestream of the solar eclipse on Aug. 21

This article was originally published on TIME.com

When is the next total solar eclipse? .
Total solar eclipses like the one crossing America today are beautiful, but they’re tragically fleeting. Totality, when the sun is completely covered by the moon, lasts just a few minutes. And the whole thing — from the start of the partial eclipse to the end — takes just a few hours. The experience is sublime, but it’ll leave you wanting. Here’s the good news: Total solar eclipses happen somewhere in the world every 18 months or so.

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