The first person credited with successfully measuring the distance between the Earth and the Sun was the ancient Greek astronomer Hipparchus. He lived in the second century BCE and is considered one of the greatest astronomers of antiquity.
Hipparchus used a method called parallax to estimate the distance to the Sun. Parallax is the apparent shift in the position of an object when viewed from different locations. By observing the position of the Sun from two different locations on Earth during a solar eclipse, Hipparchus was able to calculate the angle between the Earth and the Moon.
Hipparchus knew that the Moon's distance from the Earth was about 60 times the Earth's radius. Using this information and the angle he measured, he estimated that the distance from the Earth to the Sun was about 19 times the Moon's distance from the Earth.
While Hipparchus made significant contributions to astronomy and trigonometry, it's important to note that his estimate of the Earth-Sun distance was not very accurate compared to modern measurements. It took centuries of advancements in science, technology, and observational techniques for more precise measurements to be made, leading to our current understanding of the Earth-Sun distance.