History of the Sun

Modern science tells us that the Sun is a big hot ball of hydrogen at the center of the Solar System, and all the planets orbit around it. But ancient people didn’t have access to the same scientific tools we have today. Their understanding about the Sun was much more primitive, and often… wrong. Let’s investigate the history of the Sun.

Most life on Earth evolved with the Sun in mind; the rising and setting Sun defined the cycle of daily life for almost all life. Ancient peoples were entirely dependent on the Sun for light; only the light from a full Moon gave any way to see in the night. It wasn’t until the invention of fire that humans had any way to get any work done after the Sun went down.

Since the Sun was such an important object, many ancient people treated it with reverence and considered the Sun a god. Many worshipped the Sun, and built monuments to celebrate it. Monuments like Stonehenge in England, and the Pyramids of Egypt were used to mark the position of the Sun over the course of the year.

The first accurate measurement of the distance to the Sun was made by Greek philosopher Anaxagoras. Of course, he was threatened with death for his ideas that the Sun was a burning ball of fire, and not a god.

It was long thought that the Sun orbited around the Earth, but it was Nicolaus Copernicus who first proposed a Sun-centered Solar System. This theory gained evidence from Galileo and other early astronomers. By the 1800s, solar astronomy was very advanced, with astronomers carefully tracking sunspots, measuring absorption lines in the spectrum of light from the Sun, and discovering infrared.

For the longest time, astronomers were puzzled by how the Sun generated so much energy. It wasn’t until the 1930s when astrophysicists Subrahmanyan Chandrasekhar and Hans Bethe finally developed the theoretical concept of nuclear fusion, which explained the Sun (and all stars) perfectly.

NASA has a great website with photographs of ancient building used to mark the position of the Sun, and more about solar eclipses of historical interest.

Want more history? Here’s an article about the history of Venus, and another about the history of Saturn.

We have recorded an episode of Astronomy Cast just about the Sun called The Sun, Spots and All.

NASA Sun-Earth Day: 2009, Issue # 64
NASA Ancient Observatories