These aurorae are unique because they can cover the entire pole, whereas aurorae around Earth and Jupiter are typically confined by magnetic fields to rings surrounding the magnetic poles.
The large and variable nature of these aurorae indicates that charged particles streaming in from the Sun are experiencing some type of magnetism above Saturn that was previously unexpected. Infrared waves have longer wavelengths than visible light and can pass through dense regions of gas and dust in space with less scattering and absorption.
Thus, infrared energy can also reveal objects in the universe that cannot be seen in visible light using optical telescopes. The James Webb Space Telescope JWST has three infrared instruments to help study the origins of the universe and the formation of galaxies, stars, and planets. A pillar composed of gas and dust in the Carina Nebula is illuminated by the glow from nearby massive stars shown below in the visible light image from the Hubble Space Telescope.
Intense radiation and fast streams of charged particles from these stars are causing new stars to form within the pillar. Most of the new stars cannot be seen in the visible-light image left because dense gas clouds block their light. However, when the pillar is viewed using the infrared portion of the spectrum right , it practically disappears, revealing the baby stars behind the column of gas and dust.
To astrophysicists studying the universe, infrared sources such as planets are relatively cool compared to the energy emitted from hot stars and other celestial objects.
Earth scientists study infrared as the thermal emission or heat from our planet. As incident solar radiation hits Earth, some of this energy is absorbed by the atmosphere and the surface, thereby warming the planet. This heat is emitted from Earth in the form of infrared radiation. Instruments onboard Earth observing satellites can sense this emitted infrared radiation and use the resulting measurements to study changes in land and sea surface temperatures. There are other sources of heat on the Earth's surface, such as lava flows and forest fires.
This information can be essential to firefighting efforts when fire reconnaissance planes are unable to fly through the thick smoke. Infrared data can also enable scientists to distinguish flaming fires from still-smoldering burn scars. The global image on the right is an infrared image of the Earth taken by the GOES 6 satellite in A scientist used temperatures to determine which parts of the image were from clouds and which were land and sea.
Based on these temperature differences, he colored each separately using colors, giving the image a realistic appearance.
Why use the infrared to image the Earth? While it is easier to distinguish clouds from land in the visible range, there is more detail in the clouds in the infrared. This is great for studying cloud structure. For instance, note that darker clouds are warmer, while lighter clouds are cooler. Southeast of the Galapagos, just west of the coast of South America, there is a place where you can distinctly see multiple layers of clouds, with the warmer clouds at lower altitudes, closer to the ocean that's warming them.
Harmful health effects of IR are due to thermal injury of tissues mediated largely through water molecules but also through changes to protein structure. The main harmful health effects of high IR exposure are to the eye. The cornea, iris, lens and retina are all highly sensitive to varying degrees of thermal damage. When the cornea absorbs IR radiation with conversion into heat, this is conducted to the lens. Aggregation of lens proteins after repeated exposure to extreme heat can cause lens opacities or cataracts, as are often seen in glass workers and iron and steel workers.
Skin damage due to hyperthermia can occur but depends on the intensity and the duration of IR exposure. Long-term IR exposure of the skin without burning, such as after years of skin exposure to open fires, can cause a red-brown mottling of the skin. However, IR is not thought to play a role in initiating skin cancer. IR radiation is one of the three ways heat is transferred from one place to another, the other two being convection and conduction.
Everything with a temperature above around 5 degrees Kelvin minus degrees Fahrenheit or minus degrees Celsius emits IR radiation. The sun gives off half of its total energy as IR, and much of the star's visible light is absorbed and re-emitted as IR, according to the University of Tennessee.
Household appliances such as heat lamps and toasters use IR radiation to transmit heat, as do industrial heaters such as those used for drying and curing materials.
Incandescent bulbs convert only about 10 percent of their electrical energy input into visible light energy, while the other 90 percent is converted to infrared radiation, according to the Environmental Protection Agency.
Infrared lasers can be used for point-to-point communications over distances of a few hundred meters or yards. The receiver converts the light pulses to electrical signals that instruct a microprocessor to carry out the programmed command. One of the most useful applications of the IR spectrum is in sensing and detection.
All objects on Earth emit IR radiation in the form of heat. This can be detected by electronic sensors, such as those used in night vision goggles and infrared cameras. A simple example of such a sensor is the bolometer, which consists of a telescope with a temperature-sensitive resistor, or thermistor, at its focal point, according to the University of California, Berkeley UCB.
If a warm body comes into this instrument's field of view, the heat causes a detectable change in the voltage across the thermistor.
Night vision cameras use a more sophisticated version of a bolometer. These cameras typically contain charge-coupled device CCD imaging chips that are sensitive to IR light.
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