Radio astronomy collects the radio signals given out by objects in space, which can be used to put together a picture of something that cannot be seen with the naked eye, such as volcanoes on Venus. Many objects in space emit energy in the form of infrared waves, such as the Andromeda galaxy. Ultraviolet astronomy is used to track down the hottest stars in space, such as the Crab supernova. Radiation with the highest energy levels is called gamma ray.
Astronomers study light, and almost everything we know about the universe has been figured out through the study of light gathered by telescopes on Earth, in Earth’s atmosphere, and in space. This light comes in many different wavelengths (including visible colors); the sum of which comprises what is known as the electromagnetic spectrum. Unfortunately, Earth’s atmosphere blocks almost all wavelengths in the electromagnetic spectrum. Only the visible and radio “windows” are accessible from the ground, and they thus have the longest observational “history.” These early restrictions on the observational astronomer also gave rise to classifying “kinds” of astronomy based on their respective electromagnetic portion, such as the term “radio astronomy.”
Over the past few decades, parts of the infrared and sub millimeter have become accessible to astronomers from the ground, but the telescopes needed for such studies have to be placed in high-altitude locations (greater than 3,050 meters [10,000 feet]) or at the South Pole where water absorption is minimal. Other options have included balloon experiments, airborne telescopes, and short-lived rocket experiments.
Presently, the field of astronomy is enriched immensely by the accessibility of several high-caliber airborne telescopes (e.g., Kuiper Airborne Observatory [KAO], Stratospheric Observatory For Infrared Astronomy [SOFIA]) and space telescopes, all of which are opening up other, previously blocked windows of the electromagnetic spectrum (such as gamma ray, X ray , ultraviolet , far infrared, millimeter, and microwave). Additionally, modern astronomers often need to piece together information from different parts of the electromagnetic spectrum to build up a picture of the physics/chemistry of their object(s) of interest.
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