Lois & Clark Forums Forums General Discussion Off Topic The Big Bang and the Universe, Part 3: Enter Henrietta and Hubble!

Okay, the last part was slightly boring, wasn't it? It was all about the stars, not about the universe. But if you don't understand the stars, you can't know about the universe.

I called this part "Enter Henrietta and Hubble", but we've got to start with William, William Herschel (1738-1822), composer turned astronomer.



Born in Germany, Herschel moved to Britain, where he took up a career in astronomy along with his sister Caroline. William and Caroline were both good at using the telescope and good at making discoveries with it, and in 1781, William became the first person since antiquity to discover a new planet. Herschel saw Uranus in his telescope and realized that he was looking at a planet, not a star. Not bad!



Aqua-colored Uranus displays a featureless disk.

But for the purpose of my article here, Herschel is more important because he tried to determine the position of our own solar system in relationship to the universe as a whole. Herschel had no idea that there were galaxies in the universe, let alone that there was more than one! But he set out to find the position of the solar system among all the stars in the heavens by counting all the stars he could see in every direction. After he was done counting, he had produced a map of the starry sky which looked like this:



The bright dot near the middle is the Sun. Based on this map, Herschel concluded that the Sun and the Earth are situated close to the center of the universe! The reason why he made this conclusion was that he thought that he saw a more or less equal number of stars in every direction of the sky as he looked at it from the position of the Earth, and therefore the Earth (and the Sun) ought to be pretty much in the middle. But Herschel didn't realize that there are huge quantities of dust that hides much of our galaxy from view.



William, you couldn't see the galaxy for all the dust it contains!

Like I said, back in Herschel's days nobody knew that galaxies existed in the first place. The unawareness of the existence of galaxies was, in a way, like the unawareness of the true character of the Earth back when people had no way of getting an overview of the Earth:

Flat Earth

The discovery that the Earth was not at the center of the universe was made by a young American named Harlow Shapley:



Shapley was interested in the largest stellar clusters known, the globular clusters:



Shapley believed that we live in a huge collection of stars of some kind (a galaxy), and that the distribution of the globular clusters in the sky might tell us something about the shape of the galaxy that we live in and our own place in it. In order to determine the distribution of globular clusters in the sky, Shapley needed to measure the distance to them. But how on Earth could he do that? Even today we are completely unable to use triangulation and parallax to measure the distance to the globulars.

Okay, enter Henrietta!