Hipparchus

Hello! My name is Hipparchus. I was born a very, very long time ago, around the year 190 BCE, in a city called Nicaea. Ever since I was a boy, I loved to look up at the night sky. The stars twinkled like tiny diamonds, and I always wondered what they were and why they moved across the sky each night. To me, the sky was the biggest, most beautiful puzzle in the world, and I knew I wanted to be the one to solve it.

I decided to become an astronomer, which is a person who studies stars and planets. I spent many years on an island called Rhodes, where the sky was very clear and dark. Every night, I would go to my observatory, which is a special place for watching the sky, and I would watch the stars for hours. I decided to make a giant map of the sky, which is called a star catalog. It was a very big job. I carefully located and wrote down the position of over 850 stars. I also invented a system to describe how bright each star was, from the brightest ones to the ones you can barely see. A version of that brightness system is still used by astronomers today.

To measure things that were so far away, like the Moon, I needed a new kind of math. So, I helped invent something called trigonometry, which uses triangles to figure out distances. It was very helpful for an astronomer. While I was comparing my star map to even older ones, I made an amazing discovery around the year 130 BCE. I realized the Earth wobbles ever so slowly, like a spinning top that's getting a little tired. This slow wobble makes the stars appear to shift their position over many, many years. I called this important discovery the 'precession of the equinoxes'.

I lived to be about 70 years old, passing away around 120 BCE. Even though I lived thousands of years ago, people still remember my work. I am sometimes called the 'father of astronomy' because my star catalog and mathematical ideas helped everyone who came after me understand our amazing universe a little bit better.