"The Pinnacle of Astronomical Discoveries: A Cosmologist's Guide"

The article presents a list of the top five astronomical discoveries of all time, as determined by a theoretical cosmologist. The first discovery highlighted is the accurate measurement of the Earth's circumference by Eratosthenes around 250 BCE, using a clever method that involved observing the Sun's position at different locations. This groundbreaking discovery demonstrated the use of astronomy for precise measurements and marked a significant leap in our understanding of the cosmos.