Q&A: X-ray Astronomy

Q:
Can we look at the Sun through X-rays during a solar eclipse or would our eyes be damaged?

A:
Let's begin with how our eyes work. Our eyes are only sensitive to a narrow band of electromagnetic radiation (or light). The range of wavelengths of light that we can detect with our eyes is approximately 400 - 700 nanometers. This range is called visible light. More on the electromagnetic spectrum:

http://chandra.harvard.edu/resources/em_radiation.html

X-rays have much shorter wavelengths, and we cannot see them. In order to detect x-rays we must build telescopes like Chandra, with special detectors which can "see" X-rays.

It turns out that Chandra's X-ray detectors are sensitive enough that Chandra cannot be pointed directly at the Sun or they would be severely damaged.

Similarly, our eyes are sensitive enough that looking at the Sun directly damages them. The only time it would be safe to look at the Sun directly is during a full solar eclipse - only when the Moon covers the Sun completely. For more information on how to keep your eyes protected during eclipses, please see NASA's Eye Safety During Solar Eclipses site:

http://sunearth.gsfc.nasa.gov/eclipse/SEhelp/safety2.html