Telescopes from the Ground Up

1647: Hevelius maps
the Moon

Johannes Hevelius, a Polish brewer and councilor turned astronomer, was an expert in both constructing telescopes and in observing the heavens. He used these skills to create the first atlas of the Moon less than 40 years after the telescope was invented.

Get to the root of it

Hevelius studied the Moon over the span of four years. His refracting telescope couldn’t view the entire Moon at once, so Hevelius examined only a small portion at a time, patiently recording his observations before moving on.

He made his observations time and time again, comparing and improving his maps until their detail surpassed anything previously recorded. He even calculated the height of Moon mountains by studying the shadows they made on the Moon’s surface.

What’s in a name?

Astronomers had known since Galileo’s observations that the Moon had peaks and valleys, and perhaps other surface features similar to those of Earth. Hevelius took the assumption a step further and labeled his Moon maps with Earth names, like “alps” and “sea.”

Hevelius’ atlas, the Selenographia, published in 1647, helped other astronomers study the Moon. By referring to features on his Moon maps, they could share and compare observations more easily. Hevelius’ maps were so good that they became the main Moon reference tool for the next 100 years.

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