What instruments do scientists use to study the suns atmosphere?
Space Scientific discipline News abode
Apr 20, 1999: By studying the electromagnetic emissions of objects such as stars, galaxies, and blackness holes, astronomers hope to come to a better understanding of the universe. Although many astronomical puzzles can only be solved by comparison images of dissimilar wavelengths, telescopes are merely designed to detect a item portion of the electromagnetic spectrum. Astronomers therefore oft use images from several different telescopes to study angelic phenomena. Shown below is the Milky Way Galaxy as seen by radio, infrared, optical, Ten-ray and gamma-ray telescopes.
radio
infrared
visual
X-ray
gamma ray
Different types of telescopes usually don't take simultaneous readings. Space is a dynamic arrangement, so an image taken at one fourth dimension is not necessarily the precise equivalent of an prototype of the same phenomena taken at a later time. And oft, there is barely enough time for 1 kind of telescope to notice extremely short-lived phenomena like gamma-ray bursts. By the time other telescopes point to the object, it has grown too faint to be detected.
Then why haven't scientists created a telescope designed to look at everything at one time?
"Nature has determined the design of our telescopes," says Dr. Martin Weisskopf, an astrophysicist at NASA's Marshall Infinite Flying Heart.
The differing wavelengths among the various energies create dissimilar instrumental needs. This results in dissimilar, incompatible detecting devices.
Right: The electromagnetic spectrum. Radio has long wavelengths and low energies, while gamma rays take very short wavelengths and high energies.
Telescopes rely on the interaction between energy and matter. The atomic matter that forms the telescope has to somehow interpret the free energy emitted from astronomical objects. This energy is in the course of electromagnetic waves. Although the get-go telescope was created 400 years ago, we didn't take a complete picture of the electromagnetic spectrum until the early part of this century. As our knowledge of physics improves, scientists are able to develop increasingly superior telescopes. But every bit the engineering advances and becomes more than specialized, differences amid telescope designs become more pronounced
The Development of Telescopes
About of the universe is invisible to u.s.a. considering we only encounter the visible light portion of the electromagnetic spectrum. When virtually people think of telescopes they call back of visible light, or optical, telescopes.
When the first optical telescope appeared in the 1570s, the design was simple - i concave and one convex lens fitted inside a tube. The tube acted equally a receiver, or 'light bucket'. The lenses aptitude, or refracted, the light as it passed through the glass and thus fabricated the scene appear iii to 4 times larger. Galileo improved upon the design and by 1609 had adult a 20-power refracting telescope. Galileo fabricated the telescope famous when he discovered the valleys and mountains of the moon and spotted four of Jupiter'southward satellites.
Left: Galileo Galilei (1564-1642), Italian astronomer, mathematician and physicist.
The drinking glass lenses in the Galileo telescope weren't very clear, however - they were full of little bubbles and had a greenish tinge due to the fe content of the drinking glass. Also, the shape of the glass lenses gave the field of view very fuzzy edges.
The magnification of Galileo's telescope could only be improved past focusing the low-cal farther behind the primary lens, which resulted in longer and longer telescopes. But once
telescopes reached 140 feet in length they became almost useless for observation. It was impossible to go on the lenses properly aligned at such long lengths. Longer telescopes also required larger lenses, and after a lens reached 1 meter (3.28 ft.) in diameter it would deform, sagging under its own weight.
Right: Johannes Hevelius' 150-ft. telescope (Machina Coelestis, 1673). Reprinted with permission by the Regal Astronomical Social club, London.
Isaac Newton invented the start reflecting telescope in 1671. Past using a curved mirror to reflect and focus the light within the tube, he was able to reduce the length of the telescope dramatically. The reflecting telescope solved another problem inherent in the refracting telescope: chromatic abnormality.
In 1672, Newton
described how white calorie-free is actually a mixture of colored light. Each colour has its own degree of refraction, so curved lenses split up white light into the colors of the spectrum. This chromatic aberration acquired central images in refracting telescopes to exist surrounded by rings of different colors. Planets seen through a refracting telescope would appear to be encircled by a rainbow.
Left: Sir Isaac Newton (1642-1727), English mathematician and physicist.
By 1730, Newton's reflecting telescope had caught on with the scientific community. Even today, large optical telescopes are
based upon Newton's basic design. Yet some other bonus of Newton's reflecting telescope is that it tin also be used to written report ultraviolet and infrared low-cal. The Hubble Space Telescope, famous for its stunning optical images of the universe, besides works in the ultraviolet and infrared parts of the spectrum.
But it wasn't until the 1930s that astronomers even began looking for other parts of the electromagnetic spectrum. Karl Jansky inadvertently discovered galactic emissions of radio waves in 1933. Working at Bell Telephone Laboratories, Jansky was trying to find what caused short-moving ridge radio interference in Trans-Atlantic communications. By edifice a rotating radio telescope to look at the
horizon, he eventually discovered that nigh of the static resulted from engine ignition noise and afar lightning storms. Just Jansky as well discovered that some radio noise was coming from the center of the Milky Fashion Galaxy.
Left: The "Jansky Antenna" doesn't look much similar modern aerials, i.e., TV antennas or satellite dishes, because it was designed to receive shortwave signals coming over the horizon.
Similar optical telescopes, radio telescopes have reflectors and receivers. About radio telescopes need to be large in gild to accommodate radio'southward longer wavelengths and lower energies. Resolution is as well a gene:
low-frequency radio waves would be unfocused and fuzzy in smaller telescopes. Radio telescopes too need to exist large in order to overcome the radio noise, or "snow," that naturally occurs in radio receivers. We generate a large amount of noise on Earth besides, so smaller telescopes would lose some astronomical radio signals amid our daily product of rock music, boob tube broadcasts and cellular phone calls. An instance of a modern radio telescope is The Very Big Array in New United mexican states (right), equanimous of 27 antennas electronically combined to give the resolution of an antenna 36 kilometers (22 miles) across.
Radio and optical telescopes can be used on World, just some resolution is lost due to Globe'southward temper. By viewing from the other side of the sky, the Hubble Space Telescope allows astronomers to see the universe without the distortion and filtering that occurs equally lite passes through the Globe's atmosphere.
Infrared and ultraviolet light are affected more dramatically past the Earth's temper. Their telescopes must therefore e'er be positioned high in a higher place the basis or in infinite.
Infrared telescopes are placed on mountaintops, far to a higher place the low-lying water vapor that interferes with infrared lite.
Left: The NASA Infrared Telescope Facility 3.0 meter telescope at the elevation of Mauna Kea, Hawaii. Photo courtesy of Ernie Mastroianni.
Ultraviolet telescopes take to be placed fifty-fifty higher than infrared telescopes. The World'southward stratospheric ozone layer, located 20 to twoscore kilometers to a higher place the Globe's surface, blocks out UV wavelengths shorter than 300 nanometers. By the 1940s, scientists were launching rockets with rudimentary UV detectors onboard.
The World'southward atmosphere scatters or absorbs loftier-energy radiation, protecting united states of america from the dissentious effects of UV, Ten-rays and gamma rays. The atmosphere does such a good job that telescopes designed to detect these portions of the electromagnetic spectrum have to be positioned outside the atmosphere.
Studies of astronomical objects in high energy Ten-rays and gamma rays began in the early 1960s. Although high altitude balloons and rockets tin provide Ten-ray and gamma ray information, the best results come from satellites orbiting completely outside the World's temper. NASA'south outset X-ray telescope was launched from Kenya on Dec. 12, 1970. Because this date was the 7th anniversary of Kenya's independence, the satellite was named Uhuru (Swahili for "freedom").
Left: X-rays can exist reflected using a combination of paraboloidal mirrors and hyperboloidal mirrors. This is the arrangement of mirrors in the Chandra Ten-ray Observatory, scheduled for launch in July, 1999.
X-ray telescope mirrors are coated with gold or other metals; Uhuru'due south mirrors were coated with glucinium, for instance. The mirrors have shallow angles of reflection because Ten-rays are and then short they only reflect at angles almost parallel to the rays themselves. At steeper mirror angles the rays won't reflect - instead they will penetrate the mirror like a bullet embedding itself in a wall.
Considering gamma rays are even shorter than X-rays, there is no mode to foreclose them from passing right through a detection device. Since mirrors can't be used to focus gamma rays, a method had to be adult for detecting gamma rays indirectly.
Right: Illustration of a crystal gamma-ray detector. The electrons expelled by gamma-rays deed like a trigger on an warning, letting the detector know when gamma rays are passing through.
The
American physicist Arthur Holly Compton discovered that gamma rays would miscarry electrons as they moved through a detector. Modern gamma-ray detectors employ crystals or liquids that are triggered past these expelled gamma-ray electrons to record the passing gamma rays as flashes of light. The first gamma-ray satellite, Explorer 11, was launched in 1961, a twelvemonth before Compton's death. The Compton Gamma Ray Observatory, launched in 1991 and nonetheless orbiting the Earth today, was named in his honor.
Left: Arthur Holly Compton (1892-1962) won the 1927 Nobel Prize in physics for his work with gamma rays.
Physics 101
Most objects give off several frequencies of energy simultaneously. Your body, for instance, glows in thermal infrared down to radio. But in order to become astronomical data about different wavelengths, scientists have to use several different types of telescopes. At that place is no such thing as an 'all-wave' telescope. The problem with having one telescope able to detect the unabridged electromagnetic spectrum lies in the differences in detection techniques.
"Telescopes are designed with one goal in mind: to build a device that interacts with radiation coming from the creation," says Dr. Tony Phillips, a radio astronomer now consulting for the Scientific discipline@NASA web site.
Different energy wavelengths interact with matter in different ways. Radio waves will reflect from a metal that X-rays pass correct through. These differences in the interaction between thing and energy take resulted in telescopes designed to only adjust very specific wavelengths.
Right: A mosaic of different astronomical phenomena at various wavelengths.
Phillips says that telescopes designed for dissimilar parts of the electromagnetic spectrum often await dramatically unlike one another. "Low-frequency radio telescopes look wildly different from microwave telescopes, fifty-fifty though both written report the radio portion of the spectrum," he states. "And low-frequency radio telescopes don't deport the remotest resemblance to Ten-ray telescopes."
With nowadays technology, information technology is not possible to build one telescope able to efficiently survey the entire electromagnetic spectrum. Scientists follow established laws of physics in building telescopes, and an all-wave telescope would accept to break those laws.
"That'southward the wall that keeps us from building 1 device for everything," says Phillips.
Considering it is not currently possible to create an all-wave telescope, the next pick is to create a device that uses many telescopes at once.
"What we want is a Christmas tree," says Weisskopf. "What we want is a system that tin look at all of the emissions simultaneously." Matched telescopes could be aligned to look at 
the aforementioned thing at the same time. A device containing all the dissimilar types of telescopes would necessarily have to be a satellite and so that X-rays and gamma rays could exist detected.
Left: If an all-wave telescope were fabricated, information technology would be on the wish list for both professional and apprentice observers. On the tree, the planets are represented in society of their distance from the Dominicus (at the peak).
Several multi-wavelength observatories accept already flown - Skylab, the Solar Maximum Mission, and the Solar and Heliospheric Observatory (SOHO). The Skylab infinite station in detail is hailed as a good model for conducting multi-wavelength studies in space. Launched in 1973, Skylab had 8 coordinated telescopes located on its Apollo Telescope Mount (ATM). The eight telescopes studied the Sun's spectrum from 10-ray almost downwardly to infrared, all with very high quality resolution. Skylab was coordinated with basis-based astronomers besides.
Whenever basis observers detected active solar prominences, flares, or mass ejections, they would notify the astronauts, who would then point their telescopes to tape the upshot.
Right: Skylab space station orbiting World in 1973.
The trouble in developing this type of technology today, says Weisskopf, is 2-fold. Coin is the nigh immediate impediment. It would cost several billion dollars just to create a high quality combined optical and Ten-ray telescope.
More hard to tackle is the social mind-set of scientists. Scientists are oftentimes trained to specialize; to study just one segment of the electromagnetic spectrum. Hence we have many Ten-ray astronomers, radio astronomers, and so on, with fewer scientists following a multi-wavelength approach. Facilities and instruments are built to study only portions of the spectrum, rather than phenomena as a whole. There are no instruments designed to just report globular clusters, for example.
Phillips agrees that wavelength specialization is prevalent in the scientific community, but he believes this attitude is changing. Up until the concluding thirty years, many astronomers congenital their ain telescopes, thereby focusing all their attending on one portion of the spectrum. Today, engineers build the telescopes based on what the astronomers want to written report. Because astronomers no longer build the telescopes, they are more than willing to expect at other wavelengths.
"Astronomers are at present becoming more multi-wave literate in order to solve astrophysical puzzles," says Phillips.
Because specialized telescopes are and so well developed and are still strongly supported by scientists, the most logical arroyo would be to coordinate the telescopes already in existence. This happened recently due to an accident with satellite equipment. The Compton Gamma Ray Observatory (left) once stored information on its satellite tape recorders and dumped data near gamma-ray bursts down to ground stations several times each day. Still, in 1992 the tape recorders failed. Since there was no manner to save the data, information technology had to be transmitted instantly. The bright side of this accident was that this instant manual of information made it possible for other types of telescopes to have immediate, 'real-time' flare-up alerts. On January. 23, 1999, gamma-ray and visible light robotic telescopes coordinated an observation of a gamma-ray outburst. When the gamma-ray burst was detected, the GRO quickly sent the information out through the Internet. The Robotic Optical Transient Search Experiment (ROTSE), a visible lite
telescope, used this data to lock on to the burst 22 seconds after it began. This allowed scientists to see for the first time a gamma-ray flare-up explosion in the visible light portion of the spectrum.
Right: The Robotic and Optical Search Experiment (ROTSE), operated by Carl Akerloff at the University of Michigan.
"You desire to ask, 'Why didn't everyone do information technology this mode from the get-go?'" Weisskopf grins. "It'southward considering anybody got in their ain cars and started driving, and many were just post-obit the cars in front of them."
Such serendipitous events equally the GRO storage record failure often reveal new means of looking at old science, causing scientists to rethink ideas previously taken for granted.
Although Phillips says an all-moving ridge telescope is not currently a topic of serious give-and-take in the scientific community, satellites with coordinated telescopes accept worked well in the past. Possibly the success of Skylab and other multi-wavelength observatories, combined with the happy accident of the GRO, will inspire new and revolutionary ideas about telescopes.
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Writer: Leslie Mullen
Curator: Linda Porter
NASA Official: Gregory Southward. Wilson
Source: https://science.nasa.gov/science-news/science-at-nasa/1999/features/ast20apr99_1/
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