Why Are Space Telescopes Better Than Earth-Based Telescopes?
This NASA photo shows the Hubble Space Telescope in May 2009 as Atlantis astronauts release it into space after its fifth and final overhaul. Hubble launched into space on April 24, 1990 and celebrated its 20th birthday in 2010.
The Hubble Space Telescope has beamed hundreds of thousands of images back to Earth over the past two decades. One might call it the most skilled paparazzo, snapping countless images of the stars.
Thanks to these images, scientists have been able to determine the age of the universe and shed light on the existence of dark energy. These extraordinary advancements have been possible because the Hubble images surpass those taken by Earth-based telescopes.
While ground-based observatories are usually located in highly elevated areas with minimal light pollution, they must contend with atmospheric turbulence, which limits the sharpness of images taken from this vantage point. (The effects of atmospheric turbulence are clear to anyone looking at the stars ? this is why they appear to twinkle.)
In space, however, telescopes are able to get a clearer shot of everything from exploding stars to other galaxies.
Another disadvantage for ground-based telescopes is that the Earth's atmosphere absorbs much of the infrared and ultraviolet light that passes through it. Space telescopes can detect these waves.
Newer ground-based telescopes are using technological advances such as adaptive optics to try to correct or limit atmospheric distortion, but there's no way to see the wavelengths that the atmosphere blocks from reaching Earth, according to the Space Telescope Science Institute (STScI), which manages the Hubble research program.
One downside to space telescopes like the Hubble is that they are extremely difficult to maintain and upgrade. The Hubble is the first telescope specifically designed to be repaired in space by astronauts, while other space telescopes cannot be serviced at all.
NASA scientists estimate that the telescope will only be able to keep taking pictures for five more years.
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