Primitive peoples saw the flat Earth covered by a magic canopy low overhead. They imagined the patterns of fixed stars to be Orion the hunter, Cassiopeia the queen, and other mythological figures. The wandering lights—called planets—were gods like Jupiter, Mars, and Venus.
The ancient Greeks applied reason to the sky. They understood that the Earth was round because they could see the sails of ships disappearing over the horizon and the shadow of the Earth on the Moon during lunar eclipses. Ptolemy tried to devised intricate tables to predict the motions of the wandering lights. But these ancients viewed the stars as lights on a celestial sphere with the Earth at the center. Without technology, they could only advance their knowledge so far.
With the Renaissance and Enlightenment, people understood that knowledge was power and that applied knowledge could create tools and technology that could expand knowledge even further. In 1605, Galileo pointed a new device—the telescope—at the sky. He saw that the Moon had mountains and that the wandering planets were spheres like the Earth. Jupiter had its own moons and Venus displayed phases. His work, with that of Copernicus, Kepler, and Newton, demonstrated that the Sun, not the Earth, was the center of the solar system and that the stars were not lights on a celestial sphere but suns like our own in a vast ocean of space.
In 1835, the philosopher Auguste Comte gave as an example of knowledge forever hidden from humans the chemical composition of the stars. He was wrong! In laboratories, spectroscopes that broke up light into component colors showed that different elements glowed with different patterns when heated. When spectroscopes were attached to telescopes, astronomers were able to discover the compositions, temperatures, brightness, and, eventually, distances of the stars.
By the early twentieth century, astronomers knew that the Sun was one of millions of stars in a huge galaxy. But when Edwin Hubble trained the telescope at Mount Wilson, with its 100-inch-wide mirror, on the strange spiral nebula, he discovered that they were island galaxies themselves, perhaps millions of light years away. Even more startling, he discovered that the further away galaxies were, the faster they were moving away from the Sun. The universe was expanding!
To unwrap the further secrets of the universe, a super-telescope was needed. It took nearly two decades to construct a telescope with a 200-inch mirror on Mount Palomar. The 15-ton mirror was too big to be made of regular glass; a material new in the 1930s—Pyrex—was used. When the mirror blank was shipped from New York to California on a special train, people lined the tracks to see this incredible sight of human achievement. The telescope itself weighed over 500 tons. It had to be as sturdy as a battleship but move with the accuracy of a fine watch.
When technology allowed us to travel in space, we placed the space telescope named after Hubble in orbit above Earth's turbulent and obscuring atmosphere. But in recent years, super-fast computers, sophisticated software, and other technologies were combined in "adaptive optics" to give ground-based telescopes clear views to equal those of the Hubble telescope. Imagine a flexible mirror with hundreds of tiny pistons under it that can move up and down mere millimeters a thousand times a second. As the stars shimmer with the atmosphere, the mirror "shimmers" to compensate, bringing the stars back into focus.
Astronomy's wide appeal beyond professionals highlights the human capacity to enjoy the sheer beauty of the night sky. City lights are also beautiful but they make it impossible to see all but the brightest stars. So, go out of town some dark night. Take the kids, go to a star party of a local astronomy club, or just take your own binoculars out to a dark field in the country.
You'll see thousands of stars that will seem like millions. You'll see the Milky Way, the clouds of stars in our own galaxy stretching like a band across the sky. You'll see a smear of light that is the Andromeda galaxy, which left its source almost 2.5 million years ago. With even a small telescope, you'll see craters on the Moon, the bands on giant Jupiter, and the polar caps of Mars. And you'll see the rings of Saturn, which never fail to elicit an "Ahhh!" from anyone viewing them for the first time.
So as you gaze at the beauty of the night sky, don't think, "How small I am compared to this universe." Think instead, "How great is humanity to have the capacity and the technology to understand it!"