X Marks the Spot

July 21, 2008

Fans of B-movie director Roger Corman might recall his 1963 film, X: The Man with X-Ray Eyes. Ray Milland starred as a well-meaning scientist who develops a special kind of eye drops to expand the range of human vision beyond the visible spectrum into the ultraviolet and X-ray regimes. And like any good Hollywood scientist, he decides to test his eye drops on himself.

Voila! Instant x-ray vision! And mostly, the scientist uses his newfound power for good, until it all goes horribly wrong. (You knew it had to go horribly wrong, right? This is a horror movie!) His vision becomes more and more powerful and wide-ranging, so much so that he can only see the world through wavelengths of light the human brain just isn't equipped to process, and therefore comprehend.

I've always rather liked the film, despite the cheese factor, because it reminds me that the world we see around us reflects the limitations of human vision. There's an entire spectrum of "light" (more accurately described as electromagnetic radiation) beyond the visible range. If we could see the world through different eyes, like "X," we would see some pretty amazing things that we never suspected existed, and yet have been there all along.

It just so happens that astronomers have had "x-ray vision" for years, thanks to x-ray astronomy, which studies the emission of x-rays from various celestial objects: neutron stars, black holes, remnants of supernovae like the Crab Nebula, and so forth.

In general, this sort of emission occurs wherever you've got extremely hot gas at very high temperatures, i.e., between a million to 100 million Kelvins. In other words, it's pretty common: empty space isn't quite as empty as scientists once believed. The areas between galaxies in large clusters is filled with very hot, yet dilute (thin) gas). The energy is created as gas falls into the strong gravitational field of massive objects, and heats up in the process. That excess energy is released as x-rays.

The very first celestial x-ray source was discovered in 1962, the year before Corman's classic film: Scorpius X-1, located in the Scorpius constellation towards the center of the Milky Way galaxy. (Its discovery snagged astronomer Riccardo Giaconni a share of the 2002 Nobel Prize in Physics.) Today, astronomers know of thousands of x-ray sources in our universe.

They found them because they kept building better "eyes." It's tough to detect these powerful x-ray emissions on earth, because the earth's atmosphere absorbs them before they can reach our instruments. X-ray detectors must be located at high altitudes, and this was accomplished in the early days by mounting them on balloons or sounding rockets. But then came the dawn of the satellite age, and we could send x-ray detectors into space itself.

The latest x-ray observatory platform to enter space is the Chandra X-Ray Observatory, a satellite first launched on July 23, 1999. It's been gathering useful data ever since, and rivaling even the Hubble Space Telescope  at times with its jaw-dropping images. The first x-ray emitter it found was a supermassive black hole, Sagitarrius A, at the center of the Milky Way. Later, it took the earliest images showing the shock wave from a supernova explosion, as well as images of a smaller galaxy being "eaten" by a larger one. The discoveries are too numerous to cite them all individually, but most recently, Chandra has helped astrophysicists devise a new means of "weighing" gigantic black holes.

In Corman's film, "X" goes mad when his eyesight becomes so powerful that he begins to see things at the very edge of the universe -- including, he tells a tent revival preacher, "an eye that sees us all." Well, Chandra hasn't found that all-seeing eye as yet, but thanks to its enhanced vision, we have seen aspects of our universe that would otherwise be invisible to us. And it has yet to drive us insane.

Photo: Courtesy of the Chandra X-Ray Observatory Center.

Comments

[x-ray fluorescence]

Hi,
Thanks to astronomers for providing the x-ray vision.It's tough to detect these powerful x-ray emissions on earth, because the earth's atmosphere absorbs them before they can reach our instruments.