Temperature of the Sun
Written by Fraser Cain
What is the temperature of the Sun? The Sun is hot. Seriously, the Sun is really, really hot. Want a better answer? Okay, but the temperature of the Sun depends on which part you're looking at. Let's look at the surface of the Sun, and then we'll take its temperature all the way through.
The temperature of the surface of the Sun is 5,778 Kelvin. That's extremely hot, and gives the Sun's light its yellow color. If the Sun were any cooler, it would be more of a reddish color. And if the Sun were hotter, it would look blue. The Sun is hot enough to give off the white yellow light that we see.
But as I mentioned up top, how hot the Sun is depends on which part of the Sun you're looking at. The Sun is held together by gravity. As you move down through the Sun, this gravity creates higher pressure and temperatures. By the time you get to the core of the Sun, the temperatures have risen to 13,600,000 Kelvin. This is hot enough to create the conditions of fusion, where atoms of hydrogen are fused together to create helium.
You might be surprised to know that the atmosphere of the Sun is actually hotter than its surface. As you rise above the surface of the Sun, the temperature rises in a region called the chromosphere. Just 2,000 km above the surface of the Sun, and temperatures have risen to 100,000 Kelvin. Above the chromosphere is a transition zone where temperatures get up to 1 million Kelvin. The outermost layer of the Sun's atmosphere is the corona, where temperatures get to several million degrees Kelvin. Scientists don't actually know why this region gets so hot, but they think it has something to do with magnetic reconnection, where the Sun's magnetic field lines get twisted up, break and then reconnect.
This article on Universe Today discusses the mystery of the Sun's temperatures, and here's an article about how active the Sun can become.
Solar Views has more information about the Sun, and here's an article from the Physics Factbook about the temperature of the Sun.
We have recorded an episode of Astronomy Cast just about the Sun called The Sun, Spots and All.
Filed under: Astronomy
