Guide to Understanding the Universe

New technology allows astronomers to peer further into the universe than ever before. The science of cosmology, the study of the universe as a whole, has become an observational science. In this guide, astronomer and author Jay Pasachoff shares some of his cosmological knowledge to help you understand the universe.

Scientists may now verify, modify, or disprove theories that were partially based on guesswork.

In the 1920s, the early days of modern cosmology, it took an astronomer all night at a telescope to observe a single galaxy. Current surveys of the sky will likely compile data for a million different galaxies within a few years. Building upon advances in cosmology over the past century, our understanding of the universe should continue to accelerate.

Inside:

Hubble and the expanding universe
How do you observe the growth of something as big as the universe? The pioneering studies of astronomer Edwin Hubble in the 1920s gave the first definitive indication that the universe is expanding.

Remnants of the big bang
Radiation in the sky around us provides evidence of the big bang that gave birth to the universe.

Picking up speed
Many astronomers now agree that the universe is not only expanding but that the expansion is getting faster.

What's out there, exactly?
Astronomers are getting a better sense of the mass of the universe, but its exact contents remain a mystery.

Web links to the universe
Several excellent Web links help you start exploring the universe.

Want to learn even more about astronomy? Encarta Reference Library, on CD or DVD, includes many related articles and more multimedia, including a stunning virtual tour of Hawaii's Mauna Kea Observatory. Order Encarta Reference Library now!

Jay M. Pasachoff, A.B., A.M., Ph.D., is Field Memorial Professor of Astronomy and Director of the Hopkins Observatory at Williams College in Williamstown, Massachusetts.

Dr. Pasachoff has a great talent for teaching people about astronomy. Hundreds of thousands of amateur astronomers own well-thumbed copies of his Peterson Field Guide to the Stars and Planets, and his Astronomy: From the Earth to the Universe is a standard college astronomy textbook. He specializes in the study of the Sun during total eclipses, the formation of the elements in the early universe, the planets of the solar system, and observational cosmology. He has traveled all over the world in order to observe eclipses from prime viewing locations.