ri-science:What have eclipses ever done for science? Quite a lot, actually! The first measurement
ri-science: What have eclipses ever done for science? Quite a lot, actually! The first measurement of the width of the Atlantic ocean in the 16th Century When British settlers arrived in Virginia in the US, they weren’t sure how far across the globe they’d gone. They recorded the local time of a total eclipse of the moon - which is seen all across the night-time side of the planet. Their colleagues in London did the same, and when the travellers returned they could figure out the five hour time difference. Edmond Halley discovered that the moon is moving away from the Earth Halley realised you could back-calculate when previous eclipses would have occurred. But he noticed a mismatch between his predictions and the history books. The reason, he discovered, what that he was assuming the moon stayed the same distance from the Earth. It is actually getting further at about the rate your fingernails grow. And that means that one day (in a few million years, that is), the moon will be too far away to create any more total solar eclipses. In 1919 a solar eclipse proved Einstein’s theory of relativity Einstein’s theory predicted that the sun’s gravity should bend the light of nearby stars, meaning that in theory we should be able to see stars that are hidden just behind the sun. However, sunlight always blocks our view of these stars, and it was only during a solar eclipse that there was a short window to see if hidden stars were visible, as predicted. Astronomer Arthur Eddington travelled to West Africa and took photos that proved Einstein right. Scientists still use solar eclipses today It’s very hard to study the sun’s corona - a tenuous hot gas, which just one millionth of the light intensity of the sun. The shapes and lines of the corona show the nature of the sun’s magnetic field, and are only visible to study during an eclipse. NASA are also using this opportunity to help create the first thermal map of Mercury! Want to know more? Watch our full video. -- source link