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This image of the brown dwarf, Gliese 229b, was created using the Hubble Space Telescope. Compared to Jupiter, Gliese is about twice as large and 40 times as massive.
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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 telescopes, they called it a nebula. When examined closely, some of the nebulae had a spiral shape. So astronomers at first called these "spiral nebulae". These nebulae were all believed to be part of our Galaxy, our community of stars.

Edwin Hubble studied the "spiral nebulae" and found that they were composed of stars. These nebulae were not nebulae at all, but other communities of billions of stars held together by gravity - galaxies! Suddenly, our universe was much bigger. We realized that our Galaxy was just one of many billions of galaxies in the universe.

Hubble studied galaxies for a very long time, and after seeing many, many galaxies, he realized that he could put them into groups based on their shape: spirals, ellipticals, or irregulars. His work helped us to understand that the appearance of galaxies depends on our point of view, and on what's happening in the galaxies.

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Nebulae - The Dust of Stars

Why would we call nebulae stardust? Because the gas in nebulae is used to make new stars, and dying stars create nebulae from their gas. While stars are made of very hot, dense gas, the gas in nebulae...more

Elliptical Galaxies

Elliptical galaxies come in a range of shapes and sizes. They can be circular or egg-shaped. They can be very large and bright (giants!) or rather small and dim (dwarfs!). We can learn about how these...more

Irregular Galaxies

Any galaxy which cannot be classified as either spiral or elliptical is called an irregular galaxy. In some sense every irregular galaxy is unique in it's appearance. It doesn't have to look like the others....more

Spiral Galaxie Collisions Occur More Often

Scientists are finding strong evidence thatspiral galaxies collide more often than once thought. It was once believed that one third of all the spiral galaxies have had a collision. However, a new camera...more

Hot, Heavyweight Cluster Found!

Megan Donahue, an astronomer with the Space Telescope Science Institute, has discovered one of the heaviest and hottest galaxy clusters. Cluster MS1054-0321, located 8 billion light-years from Earth, contains...more

Hubble's New Look

The pictures released by Hubble Space Telescope's new Advanced Camera for Surveys (ACS) are nothing but FAR OUT! This new camera was put on Hubble during a servicing mission in March 2002. As can be seen...more

Draco the Dragon

Draco the dragon is a circumpolar constellation, which means it revolves around the North pole. It can be seen all year round. Draco is only present in the Northern Hemisphere, so those living in the...more

Large-Scale Structure: Your Place in the Universe

We have seen that stars cluster together to form galaxies. Galaxies also cluster together to form much larger structures. There are clusters of galaxies called Groups which contain 10's of galaxies. Our...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