When Was the Sun Discovered?

by Fraser Cain on October 7, 2009

When Was the Sun Discovered

Solar flares on the Sun


When was the Sun discovered? Obviously the Sun is such an important feature in our lives, and the absolute necessity to all life on Earth. It’s kind of impossible to say when the Sun was discovered, since the first life forms on Earth probably relied on its energy. Humans have been well aware of the Sun for tens of thousands of years, and before modern astronomy had no idea what it was.

So perhaps a better question might be, when did we realize that the Sun is a star?

The Sun is incredibly important to our lives. When the Sun is in the sky, we have day. And when the Sun is below the horizon, we have night. Our biological clocks are programmed on it, and we life our lives by this routine. Ancient peoples thought the Sun was some kind of deity, and many civilizations – like the Inca in South America – worshipped it.

The Greek philosopher Anaxagoras first proposed that the Sun was a burning ball of fire, larger than a Greek Island, and not the chariot of a god. And other astronomers were able to calculate the distance to the Sun with surprising accuracy. In the modern scientific era Lord Kelvin proposed that the Sun was ball of hot liquid that was slowly cooling. But it wasn’t until the early 20th century that scientists were finally able to figure out what the source of the Sun’s energy is.

Ernest Rutherford proposed that the Sun’s heat came from radioactive decay, and it was Albert Einstein who used his famous mass-energy equation (E=mc2) to suggest that the Sun was converting mass into energy. And finally, the theoretical concept of fusion was created in the 30s by Subrahmanyan Chandrasekhar and Hans Bethe. They were able to calculate the actual fusion reactions in the Sun that convert hydrogen into helium.

I would say then, that the Sun was really discovered in the 1930s, when astrophysicists finally understood the mechanisms working inside the Sun that gave off so much energy.

We have written many articles about the Sun for Universe Today. Here’s an article about how big the Sun is, and here’s an article about the Sun’s future.

If you’d like more information about the Sun, check out NASA’s website for the SOHO spacecraft mission.

And you should check out an episode of Astronomy Cast where we talk all about the Sun. Listen here, Episode 30: The Sun, Spots and All.

References:
NASA: The Sun, Our Nearest Star
NASA: A History of Our Understanding of the Sun – A Closer Look
NASA: The Life Cycles of Stars

About 

Fraser Cain is the publisher of Universe Today. He's also the co-host of Astronomy Cast with Dr. Pamela Gay.

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