James Webb Space Telescope: Finally, the edge of the universe and beyond
Launched in 2021 on Christmas Day, the James Webb Space Telescope is the most complex, precise and powerful space observatory ever built.
Launched in 2021 on Christmas Day, the James Webb Space Telescope is the most complex, precise and powerful space observatory ever built.
Astronomy
Jan 21, 2024
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Astronomers from Liverpool John Moores University and the University of Montpellier have devised an 'early warning' system to sound the alert when a massive star is about to end its life in a supernova explosion. The work ...
Astronomy
Oct 13, 2022
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For the first time, astronomers have directly imaged the formation and expansion of a fast-moving jet of material ejected when the powerful gravity of a supermassive black hole ripped apart a star that wandered too close ...
Astronomy
Jun 14, 2018
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(Phys.org)—Splitting water is a two-step process, and in a new study, researchers have performed one of these steps (reduction) with 100% efficiency. The results shatter the previous record of 60% for hydrogen production ...
A team of researchers with members from Universidad Nacional de San Juan, Universidade Federal do Rio Grande do Sul and Universidad Andres Bello has found evidence of a large extragalactic assembly hiding behind one part ...
(Phys.org) -- UCLA researchers have developed a new transparent solar cell that is an advance toward giving windows in homes and other buildings the ability to generate electricity while still allowing people to see outside. ...
Nanophysics
Jul 20, 2012
38
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Any science textbook will tell you we can't see infrared light. Like X-rays and radio waves, infrared light waves are outside the visual spectrum. But an international team of researchers co-led by scientists at Washington ...
Other
Dec 1, 2014
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A POSTECH research team has developed a transparent amorphous silicon that transmits visible light—which permits us to distinguish the colors of objects—enabling the development of paper-thin lenses usable in head-mounted ...
Materials Science
Feb 16, 2021
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An international team of researchers, led by scientists at the University of Manchester, has developed a fast and economical method of converting methane, or natural gas, into liquid methanol at ambient temperature and pressure. ...
Analytical Chemistry
Jun 30, 2022
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In an international scientific breakthrough, a Griffith University research team has been able to photograph the shadow of a single atom for the first time.
General Physics
Jul 3, 2012
26
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The visible spectrum is the portion of the electromagnetic spectrum that is visible to (can be detected by) the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 380 to 750 nm. In terms of frequency, this corresponds to a band in the vicinity of 790–400 terahertz. A light-adapted eye generally has its maximum sensitivity at around 555 nm (540 THz), in the green region of the optical spectrum (see: luminosity function). The spectrum does not, however, contain all the colors that the human eyes and brain can distinguish. Unsaturated colors such as pink, and purple colors such as magenta are absent, for example, because they can only be made by a mix of multiple wavelengths.
Visible wavelengths also pass through the "optical window," the region of the electromagnetic spectrum that passes largely unattenuated through the Earth's atmosphere. (Blue light scatters more than red light, which is why the sky appears blue.) The human eye's response is defined by subjective testing (see CIE), but atmospheric windows are defined by physical measurement.
The "visible window" is so called because it overlaps the human visible response spectrum. The near infrared (NIR) windows lie just out of human response window, and the Medium Wavelength IR (MWIR) and Long Wavelength or Far Infrared (LWIR or FIR) are far beyond the human response region.
Many species can see wavelengths that fall outside the "visible spectrum". Bees and many other insects can see light in the ultraviolet, which helps them find nectar in flowers. Plant species that depend on insect pollination may owe reproductive success to their appearance in ultraviolet light, rather than how colorful they appear to us. Birds too can see into the ultraviolet (300-400 nm), and some have sex-dependent markings on their plumage, which are only visible in the ultraviolet range.
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