Asked by: Karen Olsen, Leicester
The Sun emits radiation right across the electromagnetic spectrum, from extremely high-energy X-rays to ultra-long-wavelength radio waves, and everything in-between. The peak of this emission occurs in the visible portion of the spectrum.
Different wavelengths of light generally come from different regions of the Sun’s atmosphere or are due to particular atoms radiating at specific wavelengths (spectral emission lines). Visible light, for example, comes from the photosphere (or surface) whereas most infrared light comes from the lower chromosphere just above. Much of the high-energy UV and X-ray photons come from the Sun’s outer atmosphere (called the corona). This gives astronomers the ability to explore different solar features, constituents or processes simply by selecting a particular wavelength of light to observe. That is why NASA’s Solar Dynamics Observatory, for example, has an array of instruments that cover a wide range of wavelengths simultaneously.
Image credit: NASA/SDO