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Sunspots - Glossary |
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Glossary
Active Region: A
temporary area of the solar atmosphere in which sunspots,
flares, and other features of the sun can be seen.
Anthropomorphic:
The ascribing of human motivation and characterists to
inanimate objects, animals or natural phenomena.
Archeoastronomy: The study of the astronomical practices, celestial lore, mythologies, religions and worldviews of all ancient cultures.
Aurora: A faint visual (optical) phenomenon on the earth associated with geomagnetic activity, which occurs mainly in the high-latitude night sky. Typical auroras are 100 to 250 km above the ground. The Aurora Borealis occurs in the Northern Hemisphere and the Aurora Australis occurs in the Southern Hemisphere.
Convection:
The organized movement of large groups of molecules
based on their relative densities or temperatures. A hot
fluid or gas will move upward through a cooler liquid or
gas.
Corona: The outermost layer of the solar atmosphere, having low densities and high temperatures, often several million degrees kelvin. (This is A LOT hotter than boiling water!)
Cosmic Ray: An
extremely energetic charged particle, moving at nearly the
speed of light.
Facula: A bright region of the photosphere seen in
white light.
Flare: A sudden
eruption of energy on the solar disk lasting minutes to
hours, from which radiation and particles are emitted.
Gamma
Rays: High-energy radiation observed during large,
extremely energetic solar
flares.
Infrared:
infrared radiation (IR) Infrared is electromagnetic
radiation just beyond the visible spectrum. You cannot see
it with the naked eye. Infrared radiation has a wavelength
longer than visible radiation and shorter than microwave
radiation. Humans feel it as heat.
Magnetic Field: A field of magnetic force lines, usually referred to here as the pattern of magnetic force coming from and surrounding the sun or any of the planets.
Magnetic Storms: The term "magnetic storm," meaning a worldwide magnetic disturbance, was coined by Alexander von Humboldt (1769-1859). After journeying the length of Siberia, Humboldt convinced the Czar to set up a network of magnetic observatories across the Russian lands, and additional stations were established throughout the British Empire, from Toronto to Tasmania. This network clearly showed that magnetic storms were essentially the same all over the world: a steep decrease of the field over twelve to twenty-four hours, followed by a gradual recovery, which lasted one to four days. The change in the magnetic field was small, but its world-wide scale suggested that something quite big was happening out in space.
Penumbra: The brighter area that surrounds the darker umbra or umbrae at the center of a sunspot.
Plasma: Ionized gas. Any gas energized by (or containing) ions and electrons.
Photosphere: The lowest layer of the solar atmosphere; it is the solar surface that is visible in white-light images.
Prominence: Cloud-like features in the solar atmosphere that appear as bright structures in the corona above the solar limb, and as dark filaments when seen projected against the solar disk.
Sunspots: Temporary areas of concentrated magnetic field on the sun, where convection of hot matter from the sun's core is reduced, resulting in a cooler, darker area on the photosphere of the sun.
Solar Maximum: The month(s) when the number of sunspots reaches a maximum. The most recent solar maximum occurred in July 1989.
Solar Minimum: The
month(s) when the number of sunspots reaches a minimum. The
most recent minimum occurred in September 1986.
Solar Wind: The outward flow of energetic particles
and magnetic fields from the sun. Average speeds are about
350 km/sec
The Sun: One of
the 100 billion stars in our galaxy. 1,390,000 km diameter.
Temperature at the core: 15,600,000 k. Temperature at the
surface: 5800 k.
Ultraviolet:
Electromagnetic radiation at wavelengths shorter than
the violet part of visible light. Humans cannot see
untraviolet light.
Umbra: The
term for the dark area at the center of a
sunspot.
X-rays: Electromagnetic radiation of very short wavelength, and very high energy. X-rays have shorter wavelengths than ultraviolet light, but longer wavelengths than cosmic rays. Again, humans cannot see x-rays.
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