The electromagnetic spectrum extends from radio waves (with longest wavelengths and lowest energy) to gamma rays (with shortest wavelengths and highest energy). Very few spectral bands, such as visible light and radio waves emanating from distant astronomical objects, completely penetrate the Earth's atmosphere. All other spectral bands, including Extreme Ultraviolet (EUV), must be studied from space. This slide shows the various kinds of electromagnetic waves, along with the corresponding NASA satellite mission that has been designed to study it. Cooler astronomical objects emit radiation with longer wavelengths, such as radio waves, while hotter astronomical objects emit radiation with shorter wavelengths, such as EUV or X-rays.

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