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Arches National Park Geology Tour provides an extensive, visually rich description of the geology of Arches, by Deborah Ragland, Ph.D. See our DVD collection.
This image represents an expanding Universe. The arrows show that the movement is outward from the center. The spirals represent galaxies.
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Hubble Flow: The Expanding Universe

In the 1920's the famous American astronomer Edwin Hubble made a startling discovery that forever changed our view of the Universe. He found that, no matter which direction he looked into space, distant galaxies appeared to be moving away from us. The farther away the galaxy is from our galaxy the faster it moves away from us. What could be causing this? Does our galaxy smell bad? Not at all. Hubble was observing the expansion of the Universe.

What does it mean that the Universe is expanding? Well, a simple way to think of it is to imagine baking a loaf of raisin bread. As the bread rises it also expands. All of the raisins move farther apart from one another. Every single raisin would see all of the others moving away from it. So to complete the analogy, all of the galaxies in the universe are like the raisins in the bread.

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The Summer 2010 issue of The Earth Scientist, available in our online store, includes articles on rivers and snow, classroom planetariums, satellites and oceanography, hands-on astronomy, and global warming.

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Cool It! Game

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Scientists Find the True Hubble Constant!

After eight long years, the Hubble Space Telescope Key Project Team finally revealed what they believe is the real Hubble Constant. The Hubble Constant is the speed which the Universe is expanding at....more

Gamma Ray Bursts - The Most Powerful Objects in the Universe?

In the 1960's, the United States launched some satellites to look for very high energy light, called Gamma Rays. Gamma Rays are produced whenever a nuclear bomb explodes. The satellites found many bursts...more

Galaxies

During the early 1900's, which is not very long ago, astronomers were unaware that there were other galaxies outside our own Milky Way Galaxy. When they saw a small fuzzy patch in the sky through their...more

Neutron Stars

Neutron Stars are the end point of a massive star's life. When a really massive star runs out of nuclear fuel in its core the core begins to collapse under gravity. When the core collapses the entire star...more

Spiral Galaxies

Spiral galaxies may remind you of a pinwheel. They are rotating disks of mostly hydrogen gas, dust and stars. Through a telescope or binoculars, the bright nucleus of the galaxy may be visible but the...more

White Dwarfs

When stars like our own sun die they will become white dwarfs. As a star like our sun is running out of fuel in its core it begins to bloat into a red giant. This will happen to our sun in 5 Billion years....more

Algol

What's in a Name: Arabic for "head of the demon" Claim to Fame: Represents Medusa's eye in Perseus. A special variable star that "winks" every 3 days. Type of Star: Blue-white Main Sequence Star, and...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA