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ExploraTour: A Peek into the Lives of the Stars

This is an image of the supergiant star, Betelgeuse, taken by the Hubble Space Telescope. Betelgeuse is in the constellation of Orion, a familiar site from the Northern Hemisphere. But look closely at...more

ExploraTour: A Peek into the Lives of the Stars

You can sense a star's temperature -- not with your fingers, but with your eyes! The color of the star tells you how hot it is. Have you ever looked inside the toaster as the wires heat up to make your...more

ExploraTour: A Peek into the Lives of the Stars

The wire is a black body. Anything that absorbs all the radiant energy (heat and light), that strikes it, is a black body. Your black baseball cap on a hot summer day is a good example. All of the sunlight...more

ExploraTour: A Peek into the Lives of the Stars

It definitely is not black. Almost all of the photons of light that the sun produces in its core are absorbed by the sun's thin outer layer, the photosphere. Because it absorbs all the radiation that...more

ExploraTour: A Peek into the Lives of the Stars

When we apply this to stars, we find out a lot of interesting things about them. By observing the color of a star, we can figure out its temperature. If we know how far away the star is, we can calculate...more

ExploraTour: A Peek into the Lives of the Stars

Two scientists, Hertzsprung and Russell, used these very interesting properties of stars. They arranged stars on a chart according to their color and brightness. This chart is called the Hertzsprung-Russell...more

ExploraTour: A Peek into the Lives of the Stars

A great number of stars were arranged on this chart according to how bright and how hot they are. On this plot you do not see all of the individual stars. Large numbers of stars were actually scattered...more

ExploraTour: A Peek into the Lives of the Stars

New stars are formed in vast clouds of gas and dust that occupy the space between stars. If you're picturing a dense fog cloud, think again. Typically in a cloud with 1 gas atom per cubic centimeter,...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF