About CARA: Why the South Pole?

Or: Why on Earth would anyone go to Antarctica to do Astrophysics?

This is the popular-science version of the answer to this question. For a more technical answer, see site testing in the research section.

Astronomers ask many different questions about the Universe. They get answers when they observe planets, stars, galaxies and glowing clouds of gas in space. They study these objects with different types of telescopes from remote locations on the Earth. This is because some telescopes are better than others at observing certain types of light.

Planets, stars, galaxies, and glowing clouds can be seen in visible light, which is the light that most people are familiar with: red, orange, yellow, green, blue, indigo, and violet. However, there is light beyond visible light. And furthermore, most light that is not visible to our eye does not penetrate easily through the atmosphere. For that reason, astronomers have to take their telescopes to places where the air is the clearest. In some cases the telescopes even have to be placed in space, like the Hubble Space Telescope. The Hubble observes types of invisible, ultraviolet light that can't be seen through the atmosphere at all.

Light that is at the other end of the spectrum, just beyond the color red, is called (in order, getting further away from the red) infrared, sub-millimeter and then microwave light. In this part of the spectrum, where we cannot see the light, astronomers usually describe the light by the length of one wave. When we are near a hot piece of metal, we can feel infrared light even though we see nothing different. We can't see microwave light, even though we use it to cook our food. There is microwave light all over the Universe, believed to be left over from the Big Bang that created the Universe. By studying this so-called "cosmic microwave background radiation", we can learn about how the Universe formed.

The Universe is rich with things on all scales, from planets and stars, to galaxies and vast networks of galaxies. Current theories of the Universe predict that the seeds for networks of galaxies should be visible as bright and dim spots in the cosmic microwave background radiation, but these spots are very difficult to see. Clues about the birth and the formation of the first generation of stars come from observations of the youngest galaxies, and modern infrared telescopes should be sensitive enough to see these primeval galaxies. But we still have not found them in the longest exposures. We know that stars are born continuously in dense clouds in our Galaxy, but we still have not detected an actual star birth. We know that planets formed around at least one star, the Sun, but we know almost nothing about other planetary systems or how they form. Both newborn stars and planets should be seen by sub-millimeter wave telescopes.

Observations at infrared through microwave wavelengths will provide vital clues to these mysteries. At these wavelengths, absorption and emission by the atmosphere limit telescopes at mountain-top observatories. Yet above the Antarctic plateau, the infrared skies are so clear and dark that at some wavelengths, locating a telescope at the South Pole may make it many times better than anywhere else on Earth. At longer wavelengths the dryness of the South Polar atmosphere will allow us to study the birth of stars and maybe even planets. At even longer microwave wavelengths, the cool steady air at the Pole allows astronomers to look for the seeds of networks of galaxies. For much less money than putting telescopes in space, astronomers can answer exciting questions about the Universe from the coldest place on Earth, Antarctica.

Based heavily on "Why do Astronomy at the South Pole?" by J. S. Sweitzer and D. A. Harper, dated 11/22/94.