In contrast to an "ordinary" telescope, which receives visible light, a radio telescope "sees" radio waves emitted by radio sources, typically by means of a large parabolic ("dish") antenna, or arrays of them.
Many celestial objects, such as pulsars or active galaxies (like quasars), produce radio-frequency radiation and so are best "visible" or even only visible in the radio region of electromagnetic spectrum.
By examining the frequency, power and timing of radio emissions from these objects, astronomers can improve our understanding of the Universe.
Radio telescopes are also the primary means to track space probes, and are used in the SETI project..
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The first images taken by SST were designed to show off the abilities of the telescope and showed a glowing stellar nursery; a swirling, dusty galaxy; a disc of planet-forming debris; and organic material in the distant universe.
In March of 2006, astronomers reported an 80 light year-long nebula near the center of the Milky Way Galaxy, the Double Helix Nebula, which is, as the name implies, twisted into a double spiral shape.
This is thought to be evidence of massive magnetic fields generated by the gas disc orbiting the supermassive black hole at the galaxy's center, 300 light years from the nebula and 25,000 light years from Earth.
This nebula was discovered by the Spitzer Space Telescope..
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They are in fact unrelated to planets; the name originates from a supposed similarity in appearance to giant planets.
They are a short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years.
About 1,500 are known to exist in the Milky Way Galaxy.
Planetary nebulae are important objects in astronomy because they play a crucial role in the chemical evolution of the galaxy, returning material to the interstellar medium which has been enriched in heavy elements and other products of nucleosynthesis (such as carbon, nitrogen, oxygen and calcium).
In other galaxies, planetary nebulae may be the only objects observable enough to yield useful information about chemical abundances..
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They are the largest stars in the universe in terms of physical size, although they are not the most massive.
Stars with more than about 10 solar masses, after burning their hydrogen become red supergiants during their helium-burning phase.
These stars have very cool surface temperatures (3500-4500 K), and enormous radii.
The four largest known red supergiants in the Galaxy are Mu Cephei, KW Sagitarii, V354 Cephei, and KY Cygni, which all have radii about 1500 times that of the sun (about 7 astronomical units, or 7 times as far as the Earth is from the sun).
The radius of most red giants is between 200 and 800 times that of the sun, which is still enough to reach from the sun to Earth and beyond..
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Two distinct types of star cluster can be distinguished: globular clusters are tight groups of hundreds of thousands of very old stars, while open clusters generally contain less than a few hundred members, and are often very young..
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The scientific consensus is that this high redshift is the result of Hubble's law.
This implies that quasars are very distant.
To be observable at that distance, the energy output of quasars must dwarf that of almost every known astrophysical phenomenon with the exception of comparatively short-lived supernovae and gamma-ray bursts.
They may readily release energy in levels equal to the output of hundreds of average galaxies combined.
The output of light is equivalent to one trillion suns.
Quasars are believed to be powered by accretion of material onto supermassive black holes in the nuclei of distant galaxies, making these luminous versions of the general class of objects known as active galaxies.
No other currently known mechanism appears able to explain the vast energy output and rapid variability..
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