Telescopes from the Ground Up

The early reflecting telescopes weren’t flawless, however. The tin and copper alloy used to make the mirrors tarnished, which meant the mirrors needed frequent polishing. The metal mirrors didn’t reflect as much light as glass lenses transmitted, so reflecting telescopes produced dimmer images than similarly sized refracting telescopes.

Also, astronomers ran into the mechanical difficulty of manipulating large telescopes. They could build telescopes with big mirrors, but moving them around to explore the sky was difficult.

By the mid-1800s, the largest metal mirror reflectors had become powerful enough that atmospheric distortion became an obstacle. Atmospheric distortion happens because of moving pockets of air in the atmosphere. As light passes through those shifting pockets, it bends in unpredictable ways. As a result, the stars appear to twinkle if you look up at the night sky with your eyes alone. If you use a telescope, however, the image appears blurry.

In a nutshell...

Early reflecting telescopes used metal mirrors to look deep into space, but the new design presented new challenges.

Click here to see all avaliable eras.