[Christiaan Huygens] was a pretty decent mathematician and scientist by the standards of the 17th century. However, the telescopes he built were considered to be relatively poor in quality for the period. Now, as reported by Science News, we may know why. The well-known Huygens may have needed corrective glasses all along.
Huygens is known for, among other things, his contribution to astronomy. He discovered Titan, the largest moon of Saturn, and also studied the planet’s rings. He achieved this despite telescopes that were described at the time as fuzzy or blurrier than they otherwise should have been.
Huygens built two-lens telescopes, and would keep a table of which lenses to combine for different magnification levels. However, his calculations don’t align well with today’s understanding of optics. As it turns out, Huygens may have been nearsighted, which would account for why his telescopes were blurry. To his vision, they may indeed have been sharp, due to the nature of his own eyes. Supporting this are contemporary accounts that suggest Huygens father was nearsighted, with the condition perhaps running in the family. According to calculations by astronomer Alexander Pietrow, Huygens may have had 20/70 vision, in which he could only read at 20 feet what a person with “normal” vision could read from 70 feet away.
It’s a theory that answers a mildly-interesting mystery from many hundreds of years ago. These days, our troubles with telescopes are altogether more complex. If only a simple pair of glasses could solve NASA’s problems!