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Recent Podcast
A Quick Look at Ring Galaxy AM 0644-741
A Quick Look at Ring Galaxy AM 0644-741
Astronomers have used NASA's Chandra X-ray Observatory to discover a ring of black holes or neutron stars in a galaxy 300 million light years from Earth. (2018-09-06)

Putting Chandra In Its Place

NASA: We have booster ignition and liftoff of Columbia, reaching new heights for women and X-ray Astronomy.

Martin Elvis: The main thing Chandra does is take these superb, sharp images.

Cady Coleman: Nothing as beautiful as Chandra trailing off on its way to work

Narrator: It's time to explore how the Chandra X-ray Observatory fits into the modern astronomer's toolkit. As you may know, Chandra is one of NASA's so-called "Great Observatories."

Narrator: The Great Observatories were four missions selected by NASA to explore different types of radiation and really tackle the biggest questions in astronomy. The first to launch in 1990 was easily the best known: the Hubble Space Telescope, which looks at optical and infrared light. The next was the Compton Gamma-ray Observatory in 1991, which, as the name suggests, studied gamma rays, the most energetic particles known. Next up was our favorite X-ray telescope, the Chandra X-ray Observatory, in 1999, and finally the infrared-seeking Spitzer Space Telescope in 2003.

Narrator: Now, for a little more perspective on Chandra's significance for X-ray astronomy, let's turn once again to scientist Martin Elvis.

Martin Elvis: Chandra takes us to the Space Telescope era just forty years after the birth of X-ray Astronomy. That's a tenth of the time between Galileo's first telescopes and Hubble. The problem for optical astronomers was the wobbling of the Earth's atmosphere means you don't win by making bigger telescopes. So for about 200 or 250 years, they were stuck. It took Hubble Space Telescope getting above the atmosphere to get away from that wobbliness and make images that were ten times sharper, even though it's only a small telescope. X-ray Astronomy can only ever be done from above the atmosphere; our problem instead was that x-ray mirrors are really hard to make. And with Chandra, X-ray Astronomy has gone far beyond Galileo, almost up to a Space Telescope level of image clarity.

Martin Elvis: There've been mysteries that have been lying around for twenty years, some of them forty years, that weren't understood until Chandra went up, and now it's like, "Oh yeah, now I get it, that's the answer!" or "Ha! Yes, that's what I thought!" Yes: the x-ray background that Giacconi first discovered is made up of millions and millions of quasars at quite large distances from us. Or, another example, you can work out how much normal matter there is, not dark matter or dark energy but real stuff we know about, atoms. In fact if you look at very distant quasars, you can see in their light absorption by lots of little gas clouds, which add up to be just that amount of normal matter. But, as you get closer towards us, half of that gas disappears. So where'd it all go? That's called the missing Baryon's problem. It's been around for quite a long time. Chandra solved it. It turns out, the gas got heated up to X-ray temperatures, and we're sitting in a hot bath of that stuff in our Milky Way. It's a hot bath that spreads all the way to the Andromeda galaxy, and just now we've found evidence for the first time for the same kind of gas, further away, in true intergalactic space, where there are no galaxies that we know about.

Narrator: For more information about the Chandra X-ray Observatory, visit our website at

This was a production of the Chandra X-ray Center, Cambridge, Massachusetts. NASA's Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory controls science and flight operations from the CXC.

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