The
Life and Death of a PhotonThe
Life and Death of a Photon
The page you are
viewing is taken from an exhibit called MIRA: Exploring the Universe from the Central
Coast. |
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| The Birth of Light A photon is a single particle of light. The photons left over from the birth of the Universe are mostly degraded to millimeter radio waves, so most photons we see started their lives a million years ago in the core of a star. In the cores of stars, at temperatures of millions of degrees, a complex chain of nuclear reactions occurs and very high energy light, gamma rays, are released. |
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| Escaping the Star The gamma rays randomly bounce between atomic nuclei in the center of the star, slowly losing energy and heating the stellar gas. Since there are more directions out of a sphere than into one, the high energy photons slowly work their way out of the star, losing energy as they go. It takes about a million years to reach the surface of the star. Finally, a visible photon escapes from the surface of the star and starts its journey through space. |
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| End of the Journey After a few thousand or million years traveling through space, the photon enters the Earth’s atmosphere, strikes the MIRA 36-inch mirror, secondary mirror, goes through the spectrograph optics and is converted to an electron inside a layer of silicon in the electronic camera. Its journey has come to an end. Along the way, many of its companion photons were absorbed by interstellar matter, molecules in the atmosphere of the Earth, dust on the telescope mirrors, and other hazards. |
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The MIRA telescope
collecting ancient photons from distant stars to help astronomers |
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Return to MIRA home page |
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mira@mira.org |
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| Last updated February 22, 2001 by et. | |
