Search results
Results from the WOW.Com Content Network
In cosmology, galaxy filaments are the largest known structures in the universe, consisting of walls of galactic superclusters.These massive, thread-like formations can commonly reach 50 to 80 megaparsecs (160 to 260 megalight-years)—with the largest found to date being the Hercules-Corona Borealis Great Wall at around 3 gigaparsecs (9.8 Gly) in length—and form the boundaries between voids ...
In solar physics, a prominence, sometimes referred to as a filament, [a] is a large plasma and magnetic field structure extending outward from the Sun's surface, often in a loop shape. Prominences are anchored to the Sun's surface in the much brighter photosphere , and extend outwards into the solar corona .
By definition, visible light is the part of the EM spectrum the human eye is the most sensitive to. Visible light (and near-infrared light) is typically absorbed and emitted by electrons in molecules and atoms that move from one energy level to another. This action allows the chemical mechanisms that underlie human vision and plant photosynthesis.
Mathematically, for the spectral power distribution of a radiant exitance or irradiance one may write: =where M(λ) is the spectral irradiance (or exitance) of the light (SI units: W/m 2 = kg·m −1 ·s −3); Φ is the radiant flux of the source (SI unit: watt, W); A is the area over which the radiant flux is integrated (SI unit: square meter, m 2); and λ is the wavelength (SI unit: meter, m).
UVB light (< 315 nm) is filtered mostly by the cornea, and UVA light (315–400 nm) is filtered mostly by the lens. [20] The lens also yellows with age, attenuating transmission most strongly at the blue part of the spectrum. [20] This can cause xanthopsia as well as a slight truncation of the short-wave (blue) limit of the visible spectrum.
300 nm – greatest particle size that can fit through a HEPA (high efficiency particulate air) filter (N100 removes up to 99.97% at 300 nm, N95 removes up to 95% at 300 nm) [83] 300–400 nm – near ultraviolet wavelength; 400–420 nm – wavelength of violet light (see Color and Visible spectrum) 420–440 nm – wavelength of indigo light
The Star-Spectroscope of the Lick Observatory in 1898. Designed by James Keeler and constructed by John Brashear.. Astronomical spectroscopy is the study of astronomy using the techniques of spectroscopy to measure the spectrum of electromagnetic radiation, including visible light, ultraviolet, X-ray, infrared and radio waves that radiate from stars and other celestial objects.
A demonstration of the 589 nm D 2 (left) and 590 nm D 1 (right) emission sodium D lines using a wick with salt water in a flame. The Fraunhofer C, F, G′, and h lines correspond to the alpha, beta, gamma, and delta lines of the Balmer series of emission lines of the hydrogen atom. The Fraunhofer letters are now rarely used for those lines.