What did alhazen discover about space?

Alhazen: The Dude Who Questioned the Universe (and a Lot More)

Okay, so you’ve probably heard of Alhazen, right? Maybe not. But trust me, this guy was a total rockstar back in the Islamic Golden Age – around 1000 AD. Officially, he was Abu Ali al-Hasan ibn al-Hasan ibn al-Haytham, but Alhazen is way easier to remember. While most folks know him for his mind-blowing work on optics – like, how we actually see – he was also seriously into space. And what he discovered is pretty darn cool.

Think of Alhazen as the ultimate “why?” guy. He wasn’t content just accepting what everyone else said, especially when it came to Ptolemy, the big cheese of ancient astronomy. Ptolemy’s ideas about the universe had been the gold standard for centuries, but Alhazen wasn’t afraid to say, “Hold on a minute…”

One of Alhazen’s biggest contributions was his book Doubts Concerning Ptolemy. Talk about a mic drop! In it, he basically picked apart Ptolemy’s theories, pointing out inconsistencies and things that just didn’t make sense. Ptolemy’s model, while mathematically sound, relied on some weird concepts like epicycles and equants to explain how planets moved. Alhazen was like, “Yeah, but does that really work in the real world?”

Now, Alhazen wasn’t trying to throw Ptolemy under the bus completely. He still believed in a geocentric model, meaning he thought the Earth was the center of the universe. But he wanted a model that was both mathematically accurate and physically possible. It’s like saying, “Okay, I get the math, but how does this actually happen?” Interestingly, he got rid of Ptolemy’s equant, a move that Copernicus applauded centuries later when he proposed a sun-centered system!

But here’s where it gets even cooler. Alhazen wrote a book called On the Configuration of the World. Imagine this as “Astronomy for Dummies” – but, you know, a thousand years ago. It explained the basics of the universe in a way that regular people could understand. No crazy equations, just clear explanations of how everything worked. This book was a smash hit, translated into multiple languages and influencing everyone from scholars to everyday folks who just wanted to know what was going on up there.

He even got into the nitty-gritty of planetary motion, developing what we now call “celestial kinematics.” Basically, he was figuring out how to map the movements of planets, the Sun, and the Moon using geometry. He noticed that Mercury and Venus didn’t just follow perfect circles; they wobbled a bit. This was a big deal because it challenged the idea that all planets followed fixed paths.

And get this – Alhazen even tried to figure out how high the Earth’s atmosphere is! By watching how long twilight lasted, he estimated it to be about 55 miles high. That’s pretty impressive for someone without modern equipment!

Remember the “moon illusion,” where the Moon looks bigger when it’s near the horizon? Alhazen tackled that one too. At first, he thought it was just atmospheric refraction (bending of light), but he kept digging, showing he wasn’t afraid to rethink his initial ideas.

So, while Alhazen might be Mr. Optics to most people, his contributions to astronomy are nothing to sneeze at. He challenged the status quo, made complex ideas accessible, and paved the way for future scientists to explore the universe. They even named a crater on the Moon after him, which is a pretty awesome way to say, “Thanks, dude, for expanding our minds!” And an asteroid too! Not bad for a guy who just wanted to know how the universe really worked.