Absolute Zero and the Conquest of Cold  




Topic 9: Astronomy

There are all sorts of machines that work better when kept at temperatures near absolute zero. Some of these machines affect areas you might not expect, like astronomy. There are instruments on telescopes -- including the Hubble Space Telescope -- that need incredibly cold temperatures to work.

The advantage of looking at stars through a telescope instead of with your naked eye is not only that telescopes magnify everything dramatically but also they can see light that’s invisible to the human eye. The kind of light we can see is just a drop in the bucket compared to all the kinds of light -- or radiation -- that exists in the world. Instruments on telescopes can be built, for example, to see infrared radiation. To us, infrared radiation feels like heat, but in fact it too is a kind of light wave. (Infrared radiation is also what night goggles detect -- they are actually "seeing" heat, which is why people and animals, which are much warmer than their environment, stand out so well.)

It’s pretty obvious that “seeing” heat could be helpful to astronomers -- you can imagine how detecting the heat streaming off of different stars and galaxies could help astronomers understand things like what a star is made of or how hot it is. But if that instrument sits at room temperature it will "see" heat coming in from all around it. It's not going to get a good reading on the stars -- just as if you were looking for a faint star and someone kept shining a flashlight in your face. So, instruments that detect infrared radiation have to be kept extremely cold -- down to temperatures just a few degrees above absolute zero. Those temperatures can only be achieved using cryogenic techniques that have been perfected by low-temperature physics, like using liquid helium.

Additional Resources


More Topics

  • Topic 1: Measuring the Cold - Thermometers
  • Topic 2: Understanding Heat and Energy
  • Topic 3: States of Matter
  • Topic 4: Refrigeration
  • Topic 5: Cryogenics
  • Topic 6: The Quest for Absolute Zero
  • Topic 7: How Animals Survive the Cold
  • Topic 8: Superconductivity
  • Topic 9: Astronomy
  • Topic 10: Spaceflight
  • Topic 11: Agriculture
  • Topic 12: Cold Medicine
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