X and Gamma Ray Telescopes
Radio telescopes, which we talked about last time, help us explore the non-visible wavelengths that are longer than visible light. Since radio waves penetrate our atmosphere, we don’t have to send the telescopes into space to find them. They also can be ganged in order to increase their power.
The next development was telescopes that explore wavelengths shorter than visible light. Virtually none of these wavelengths—the X-rays and gamma rays—reach the surface of the earth. They are either reflected off the gasses of our atmosphere or are absorbed by them. In order to study these wavelengths, scientists devised both the instruments that can interpret the information and the means to place them securely at appropriate distances from Earth. Thus there are the obvious disadvantages of the great expense and engineering expertise necessary to launch, hold in place, and monitor space exploration. But, space frees these telescopes from the pollutions of Earth’s atmosphere, both its turbulence (that makes the stars twinkle), its frequent clouds, and the dirt we spew into it.
X-ray and gamma ray telescopes were first put to use in the early 1960s. They have greatly increased what we can “see” in our universe beyond the capabilities of optical telescopes; at the same time, they have deepened our puzzlement at what the universe contains and what it all means.
Among these puzzles that astronomers have found using X-ray ’scopes is a strong source of X-rays at the center of our galaxy; they believe it shows a lot of violent activity there that they call a black hole. But—what does a black hole really do? (See McCandless’s article, “Speculations on a Black Hole Experiment, p. 5) How does it start? They have studied X-ray emissions from comets and the churning vortexes on the Sun’s surface.
By chance, in the 1970s when the US Vela spy satellite series was looking for Soviet nuclear testing, it recorded instead gamma ray flashes coming from outer space. Subsequent discoveries have shown that these violent bursts of energy occur anywhere, any time. Scientists do not understand them, but they believe they originated between three and ten billion light years away. (That’s a long time ago!) Among the most powerful known events in the universe, some last (or, more accurately, lasted) only fractions of seconds.
There’s always more to explore. Perhaps there are signals we don’t know exist. Certainly there are ways of looking that we haven’t thought of.
The pictures that astronomers have created from the data of all these ’scopes show our universe to be both violently explosive and fantastically beautiful. They draw us into the mysteries at the basis of all science: How much more? What does it all mean?
Sources: Kaufmann, Comins, Discovering the UniverseNASA websites, “Telescopes” Encyclopedia Britannica, 14th ed., “Telescopes”