Telescopes from the Ground Up

Solar Telescopes

What’s my line?

Astronomers have studied the Sun for a long time. Galileo, among others, had examined sunspots. Other early astronomers investigated the outer area of the Sun, called the corona, which was only visible during solar eclipses.

Get to the root of it

Even early on, instruments were essential to the study of the Sun. One was the spectroscope, a device invented in 1815 by the German optician Joseph von Fraunhofer. The spectroscope spreads sunlight into colors and helps astronomers figure out what elements stars contain. Scientists used a spectrum of the Sun to discover the element helium, named after the Greek word for Sun, “helio.”

Lighting the way

In the 1890s, when the American astronomer George Ellery Hale was still a student in college, he combined the technology of spectroscopy and photography and came up with a new and better way to study the Sun. Hale called his device the “spectroheliograph.”

The spectroheliograph allowed astronomers to choose a certain type of light to analyze. For example, they could take a picture of the Sun using only the kind of light produced by calcium atoms. Some types of light make it easier to see details such as sunspots and solar prominences.

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