Astronomers use many ways to look at the universe. They are either confined to the Earth’s surface, either from high altitudes or from the space outside the Earth’s atmosphere.
- Radio astronomy observes radiation with a wavelength size smaller than one millimeter. The big difference between radio observation and other types of measurements, is that the radio waves are looked upon as a continuous wave of information, rather than singular photons. This method is best suitable to measure long distance waves, rather than short ones. Supernovas, interstellar gas and pulsars are some of the objects that can be studies with the help of radio wavelength.
- Infrared astronomy detects the infrared radiation emitted. It is used to study cold objects, that are normally not visible under the normal light. These are planets, nebulae or circumstellar disks. It can see through the cosmic dust, thus reach distances to the young stars or to the cores of different galaxies.
- Optical astronomy is the most common method used to look at the sky. It derives from the photographic equipment, but it later developed into digital and particular detectors that are stored into a computer’s memory. The visible light extends between 400 nm and 700 nm, which is between the ultraviolet and infrared radiations.
- Ultraviolet astronomy measures the wavelength from 10 to 320 nm. The atmosphere of the Earth protects its inhabitants of these rays, so the measurements are made from space. The blue stars in other galaxies and ours are easily observable, because they are very bright in this wavelength.
- X-ray astronomy studies the electrons that orbit the magnetic fields. These gases are above 10 million kelvins and appear as thermal emissions. These observations are made from outside the Earth’s atmosphere.
- Gama ray astronomy studies the shortest waves generated by the electromagnetic field. Satellites are specialized to detect these types of radiations.