Total solar eclipses like the one that will cross the U.S. on Aug. 21 have captured the attention of astronomers throughout history mdash and have often led to advances in our understanding of how the universe works.
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#8217s 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 #8220sun.#8221 Today, it#8217s known as helium.
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#8217s corona, the sunrsquos outer atmosphere. This was the first indication that the corona is millions of degrees hotter than the sun#8217s surface, a mystery that puzzles astronomers to this day.The Brief Newsletter Sign up to receive the top stories you need to know right now. View Sample Sign Up Now
Perhaps the most interesting eclipse-based discovery came in 1919. Albert Einsteinrsquos 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#8217t 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 sunrsquos limb, or edge, before a solar eclipse, then measured their positions again during the eclipse. He found that the stars#8217 positions had changed. The only explanation was that the mass of the sun was bending space-time and curving the starsrsquo light. They looked to be in different positions, but it was really an effect of the sunrsquos 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#8217s a good moment to remember the cosmic event#8217s history of illuminating our place in space. (责任编辑：彩票代购网站源码) 本文地址：http://www.troxtabo.com/famen/jiezhifa/201908/3256.html