Image of the solar corona in white light (outer circle, blue and white) and X-Rays (inner circle, red, yellow, and black) on April 22, 1994, courtesy of the High Altitude Observatory and the Yohkoh Science team. The dashed circle is the solar radius.
Click on image for full size
Image courtesy of the High Altitude Observatory, National Center for Atmospheric Research (NCAR), Boulder, Colorado, USA. NCAR is sponsored by the National Science Foundation.The solar X-ray image is from the Yohkoh mission of ISAS, Japan.
The Solar Atmosphere
The visible solar atmosphere consists of three regions: the
photosphere,
the chromosphere, and the solar corona. Most of the visible (white) light
comes from the photosphere,
this is the part of the Sun we actually see.
The chromosphere and
corona also emit white light, and can
be seen when the light from the photosphere is blocked out, as occurs in
a solar eclipse.
The sun emits electromagnetic radiation at many other wavelengths as well.
Different types of radiation (such as radio, ultraviolet, X-rays, and gamma
rays) originate from different parts of the sun. Scientists use
special instruments
to detect this radiation and study different parts of the solar atmosphere.
The solar atmosphere is so hot that the gas is primarily in a plasma state:
electrons are no longer bound to atomic nuclei, and the gas is made up
of charged particles (mostly protons and electrons). In this charged
state, the solar atmosphere is greatly influenced by the
strong solar magnetic fields that thread through it.
These magnetic fields, and the outer solar atmosphere (the corona) extend out into
interplanetary space as part of the solar wind.
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