It would seem that when it comes to observing the universe, the larger the instrument, the better. This is true up to a point, but there are limits —limits not imposed by technology but by nature itself.

Surrounding Earth is a life-sustaining atmosphere that stands between our eyes and the radiation that falls upon Earth from outer space. This radiation is comprised of a very broad spectrum of energies and wavelengths. Collectively, they are referred to as the electromagnetic spectrum. They range from radio and microwave radiation on the low energy (long wavelength) end through infrared, v isible, ultraviolet, and x-rays to gamma rays on the high energy (short wavelength) end.

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Gases and other components of our atmosphere distort, filter, and block most of this radiation permitting only a partial picture, primarily visible radiation and some radio waves, to reach

Earth’s surface. Although many

things can be learned about our

universe by studying it from the

surface of Earth, the story is incomplete.

To view celestial objects over the whole

range of the

electromagnetic spectrum,

it is essential to climb

above the atmosphere into

outer space.

From its earliest days, the National Aeronautics and Space Administration (NASA) has used the emerging technology of rockets to explore the universe. By lofting telescopes and other scientific instruments a bove the veil of Earth’s atmosphere, NASA has delivered a treasure house of information to astronomers, leading them to rethink their most fundamental ideas about what the universe is, how it came to be, how it functions, and what it is likely to become.

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[Via NASA Educational Technology Services]

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