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Hands On Mineral Identification helps you to identify over 14,500 minerals! By M. Darby Dyar, Ph.D. See our DVD collection.
This diagram shows the structure of the Sun's interior. Two major regions inside the Sun, the convective zone and the radiative zone, are named for the way heat travels through them.
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Thermal Physics

The scientific field of thermal physics is concerned with heat and temperature. When we delve into topics such as global warming, the structure of Earth's solid and liquid cores, and the way in which energy flows from the center of the Sun to its surface, we need an understanding of thermal physics.

Temperature is a familiar concept that is a cornerstone of thermal physics. Three scales for measuring temperature are in common use: Fahrenheit, Celsius (or Centigrade), and Kelvin. The temperature of a gas is actually a measure of the average speed with which molecules or atoms are hurtling about. We infer the temperatures of stars from their colors; hot stars are blue while cooler ones are red.

In our everyday speech, heat and temperature are nearly synonymous. In the language of thermal physics, the two terms have precise and quite different meanings. Heat is essentially the amount of thermal energy stored within an object. Heat can flow from one object to another, transferring energy in the process. The flow of heat can melt ice or warm the surfaces of planets near a star. The Laws of Thermodynamics describe the fundamental physics of heat and its flows.

Heat tends to flow from hot places to cold ones, and often drives the motions of other materials. Convection and conduction are two common ways by which heat can flow. Electromagnetic radiation, especially at infrared wavelengths, can convey heat across a vacuum. We study heat flows to understand the diffusion of gases, the circulation of ocean currents, the outflow of energy from the Sun, and the workings of rocket motors.

Last modified May 28, 2010 by Randy Russell.

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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