Aristyllus facts for kids

Aristyllus (pronounced Ah-ris-TIL-us) was an important Greek astronomer who lived around 261 BC. He was one of the first people to carefully observe stars as they crossed the sky's middle line, called the meridian. His work helped ancient scientists understand the positions of stars.

Aristyllus: An Ancient Star-Gazer

His Amazing Star Observations

Aristyllus was part of a group of astronomers who followed the teachings of Timocharis. He was especially good at observing stars. He measured how far stars were from the celestial equator. This measurement is called "declination."

Six of his star measurements are still known today. They are written in a famous old book called the Almagest. His measurements were very accurate for his time. He was also very careful, rounding his results to the nearest quarter of a degree.

A New Look at Old Data

For a long time, people thought Aristyllus lived around 300 BC. This made his star data seem less accurate than it actually was. But later, scientists used a special math method to find his correct date.

When they realized he lived around 261 BC, they saw how amazing his work was. His star measurements were among the most accurate in ancient times. His data also suggests that he likely worked in the ancient city of Alexandria.

Aristyllus on the Moon

There is a lunar crater named after Aristyllus. This crater is called Aristillus. It is located near the Moon's meridian, which is like the Moon's middle line.

The crater's position on the Moon is similar to how far Alexandria is from the Earth's equator. It is a fitting tribute to an important ancient astronomer.