Describes quasars as being classified within the category of an active galaxy. A description of the emergence of high-energy. Definitions of key words are provided.gamma-ray quasars as an important component of the gamma-ray sky.

Do galaxies collide? Apply concepts of scale to grasp the distances between stars and galaxies.

By studying the properties of the universe's largest pieces we can learn quite a lot about our own world and galaxy. [6:43]

This site provides a description of the universe and what it contains. Includes links to definitions, activities, and an audio song. Printable version available.

An image of a quasar. The large redshifts imply that quasars lie near the edge of the observable universe and must emit tremendous amounts of energy. There are also many embedded links to related topics.

Travel the universe and learn about galaxies. Investigate Hubble Deep Field observations to learn more.

A tutorial that looks at the components within a galaxy such as gas, dust, stars and objects that orbit stars. A PDF file of the tutorial is available.

Globular clusters, compact groups of about a million stars that move around together in galaxies, are among the oldest objects found in the universe. Since they are found most galaxies and since they've been around for so long, globular...

Biographies of people throughout history who looked at the sky and wondered what was there. Links to a detailed description of the planets and interactive activities.

A video and a short multiple-choice quiz on the Universe and what it is made up of.

This site provides an introduction to the origin of the universe for the young child and the Big Bang theory. There is also a song about the Doppler Shift. Vocabulary glossary and printable version available.

PBS site explores these building blocks of the universe as well as their various types and clusters.

PBS site provides various views of spiral galaxies. (Quick Time required) With this technology, you can manipulate the image to spin it around and look at it from various angles.

In 1995, scientists pointed the Hubble Telescope at an area of the sky near the Big Dipper. The location was apparently empty, and the whole endeavor was risky- what, if anything, was going to show up? But what came back was nothing...

Basic information about the universe, its origin and composition. Also includes information about galaxies, stars, and the sun.

At this site from HubbleSite you can learn all about galaxies and black holes. Click on the movie link and discover how old the universe is or study about what happens when two galaxies collide!

This site from the University of Cambridge allows you to view information on spiral, elliptical, and Milky Way galaxies, as well as galaxy clusters. Provides basic facts about each one.

Find out how galaxies are classified and then see if you can apply that knowledge to identify the different types of galaxies. In addition to explaining Hubble's galaxy classification system, the site has links to Hubble Space Telescope...

Site provides an introduction to dark matter and what it really is. Provides links to a quiz as well as facts about dark matter. Offers links to additional resources as well as related topics.

Students will work in groups to make up a story and picture that explains how someone living thousands of years ago in their location might have explained the Milky Way.

This Imagine the Universe site provides an introduction into the multiwavelength universe and astronomy. Site provides graphics, links to a quiz, facts on this topic as well as teacher resources.

Provides a general overview of irregular galaxies, including a specific look at type I and type II irregulars.

Provides a general overview of spiral galaxies, including descriptions of the different classes of spiral galaxy.

A set of podcasts outlining a four-step process for understanding the vastness of our universe, from the vicinity of the Earth and Moon, out into distant galaxies. Downloadable instructions and a handout are included, as well as...