Q&A: X-ray Astronomy

Q:
What is an X-ray telescope? How does it differ from other types of telescopes?

A:
X-rays do not reflect off mirrors the same way that visible light does. Because of their high-energy, X-ray photons that strike a mirror directly will penetrate into the mirror in much the same way that bullets aimed directly at a surface will bury themselves in it. Likewise, just as a bullets can ricochet off a surface when they hit it at a grazing angle, so too will X-rays ricochet off mirrors if they hit at very shallow angles, like a stone skipping across the surface of a pond. These properties mean that X-ray telescopes must be very different from optical telescopes. Please visit http://chandra.harvard.edu/xray_astro/reflect/reflect.html for more information.