Sir William Herschel (1738-1822) was a German-born British scientist who discovered Uranus, the first planet discovered since ancient times. He also discovered two moons of Uranus (Oberon and Titania) and two moons of Saturn (Mimas and Enceladus).
We take new discoveries in science for granted. We expect to read about a new one every few months in the newspaper. But in the 1700s people thought Newton was the last word in science, that everything had been discovered already. Uranus was a breath of fresh air.
Herschel was the greatest astronomer of his day. He became that by making the best telescopes in the world and studying every single part of the night sky with them, not knowing what he would find there.
He came to England from Germany at age 19, not wanting to fight in the German wars, even though his father was in the army. Instead he taught music in the English town of Bath.
He taught himself Latin and Italian and read Newton’s book on optics, about how glass lenses bend light. He started making lenses of his own and then, in the 1770s, telescopes. He brought over his sister Caroline from Germany and she helped him.
One by one he looked at each star in the sky with his telescope. Then in 1781 he came upon a star that was not a star. It was a small little circle of light.
At first he thought it was a comet, but when he and Laplace worked out its orbit, they found out it circled the sun beyond Saturn. It was a planet like Saturn!
You can see it with the naked eye if you know where to look. It looks like a very faint star and had been appearing on star maps, but it moved so slowly no one knew it was a planet. Not till Herschel.
He named it George’s Star, after the king. Others called it Herschel. Someone else named it Uranus, after Saturn’s father. That is the name that caught on.
Herschel thought there was life on the other planets, even on the sun. He did not think the sun was a huge ball of fire like we do: he thought its clouds were on fire, that sunspots were holes through the clouds where you could see a world below.
He tried to find out how far away the stars were but had no luck. But he did find out that the sun is moving among the stars. It is headed for the constellation of Hercules.
He also found out that the sun is in a huge wheel made of stars, what we now call the Milky Way Galaxy. He saw other such wheels of stars through his telescope, other galaxies, very far away.
Uranus takes 84 years to go round the sun. When it returned to the place where it was when Herschel was born, he died.
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