General

Here's a piece of high-energy astrophysics trivia (you never know when you might need to know these things). Where does the "X" in "X-ray" come from?

Speaking in broad generalities, there are two main classes of physicist: those who generate new hypotheses and those who generate new data. The former are called "theorists" and the latter, in most of physics, are called "experimentalists." In astrophysics, we're called "observers" because we can't do experiments in the traditional sense. We have no knobs to turn, no switches to flip; we can't turn the dial to a maximally spinning black hole just to see what happens (oh, what fun that would be!).

The Chandra X-ray Observatory is now in its ninth year in orbit around the Earth, and things are sometimes lonely out there. So we've been helping Chandra to use the web to reach out to others who like to network online. Here are a few ways to get in touch with Chandra.

The detectors we use on Chandra are different from detectors on optical telescopes. Most of the Chandra images are taken with what's known as a Charged Coupled Device (CCD). The CCD is the type of detector that's in the camera in your cell phone, or in your digital camera.

Shown from left: Chandra X-ray image of supernova remnant G292.0+1.8, Chandra X-ray image of young star cluster Westerlund 2, and a multiwavelength view of galaxy M82 (Chandra X-ray, Spitzer Infrared, Hubble Optical).

Explore the Universe from your computer using Sky in Google Earth. The latest version of Sky in Google Earth, released on January 9, 2008, now contains X-ray images from NASA's Chandra X-ray Observatory. Pictured: Cas A and M82. Learn more about Sky in Google Earth

The latest version of Sky in Google Earth, released on January 09, 2008 at the American Astronomical Society meeting in Austin, Texas, now contains X-ray images from NASA's Chandra X-ray Observatory. Along with images from other NASA satellites, the addition of Chandra into Sky in Google Earth provides scientists, students, and amateur stargazers new opportunities to explore the Universe across the electromagnetic spectrum. Eli Bressert, Image Processor at the Chandra X-ray Center, discusses the Sky in Google Earth update.

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Like the jelly beans in this jar, the Universe is mostly dark: 96 percent consists of dark energy (about 70%) and dark matter (about 26%). Only about four percent (the same proportion as the lightly colored jelly beans) of the Universe - including the stars, planets and us -is made of familiar atomic matter. Read about the make up of the Universe

A doctor's x-ray machine consists of two parts: an x-ray source at one end, and a camera at the other. The arm or mouth or other body part to be examined is placed in between these two parts. X-rays from the source shine through the impeding body part, and the camera records the x-rays that reach the photographic film inside. Bone is denser than muscle tissue and skin, so it stops more of the x-rays (and hence fewer x-rays make it to the region of the film that's behind the bone).

Dr. Patrick Slane from the Chandra X-ray Center presented an overview of the Chandra X-ray Observatory to NASA's museum alliance. This part of the conversation talks about how X-ray Astronomy connects to medical X-rays and what people experience with X-rays from the doctor.

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Everybody is familiar with going to the doctor and having a big X-ray machine kind of point at you and having a film put somewhere and then getting a picture. And at many times, I’ve been asked the question, is it dangerous to shine all those X-rays out in the space from Chandra.