The study of the universe and the objects in it through scientific investigation. Since much of contemporary astronomy uses
the laws and methods of physics, the terms “astronomy” and “astrophysics” are usually used interchangeably. However, modern astronomy also uses techniques from many other scientific disciplines, including chemistry, geology, and biology, for which the terms astrochemistry,
planetary science, and astrobiology are increasingly used.
The use of geological knowledge and methods in analyzing close-up observations from spacecraft of planets and their satellites and of comets and asteroids closely links the disciplines of astronomy and planetary science. Indeed, the discovery of planets around distant stars holds for even closer relations in the future. Methods of studying molecules in interstellar clouds involve chemical knowledge. Planetary science and astrochemistry come together with astronomy in the search for life outside the solar system, part of the search for extraterrestrial intelligence (SETI). The National Aeronautics and Space Administration (NASA), the United States space agency, has placed a priority on astrobiology, including the investigation of Mars and the bringing of samples back to Earth from Mars.
Astronomers often lead in employing new technologies, pushing them to the limit in exploring extremely faint signals in various parts of the electromagnetic spectrum. Nearly all
astronomical research is now heavily dependent on computers. Astronomical imagery is now dominated by light-sensitive silicon chips known as charge-coupled devices (CCDs), which are approximately 100 times more sensitive than film. Fiber optics are used for a variety of astronomical purposes, including the taking of hundreds of galaxy images simultaneously from the field of view of a telescope and bringing the light to a spectrograph that can produce simultaneous spectra of all the objects. The technology of active optics, in which the shape of a mirror is changed slightly at a high rate (often faster than 1 Hz) to compensate for the blurring of astronomical images caused by the Earth''''s atmosphere, is being increasingly pursued to eliminate the twinkling of stars.
See also Adaptive optics; Fiber-optics imaging.