The last time I talked about the sun, I was very brief. I would like to go into more detail so we can get a better picture of how magnificent this star is.
Our sun is the center of our solar system. It is estimated to be 4.6 billion years old. Everything in our solar system moves around the sun. According to NASA, this means there are “eight planets, at least five dwarf planets, tens of thousands of asteroids, and hundreds of thousands to three trillion comets and icy bodies” that orbit the sun.
The sun makes up 99.8% of the mass of our solar system. Its volume is 338,102,469,632,763,000 mi³. That’s 338 quadrillion cubed miles. To help wrap our heads around that gigantic number, we can also say that over one million Earths could fit into the sun. Even then it’s quite difficult to understand how massive this star is, and it’s not even a solid body!
The sun is made up of 92.1% hydrogen and 7.8% helium. The sun has six regions: “the core, the radiative zone, and the convective zone in the interior; the visible surface (the photosphere); the chromosphere; and the outermost region, the corona.” In the core, the temperature is roughly 27 million degrees Fahrenheit. It is so hot that thermonuclear fusion could happen. The majority of the heat and light that reaches Earth comes from the core. Energy from the core moves outward, into the radiative zone. It takes the energy about 170,000 years to get from the core to the convective zone. Again, that shows how huge the sun is!
The temperature in the convective zone is greatly reduced, only 3.5 million degrees. At this region of the sun plasma moves upwards towards the photosphere.
The photosphere is 300 miles thick but still radiation finds a way to escape. This radiation then travels away from the sun, travelling for 8 minutes before we can see it (as sunlight) on Earth. The temperature in the photosphere is a cool 10,000 degrees. The chromosphere and the corona are above the photosphere. The corona reaches all the way to Pluto (Dr. Tony Phillips, 2008). Both it and the chromosphere can only be seen during a total solar eclipse. The red rim is the chromosphere while the white crown is the corona. Surprisingly here, the temperatures actually rise and can get as high as 3.5 million degrees. According to NASA, scientists have not been able to explain why this happens, although with new data coming in they are working on an answer.
The sun is the closest star to Earth, being 92.96 million miles (149.60 million kilometers) away. This distance is known as an astronomical unit (AU) and is used to measure distances all throughout the solar system.
So let’s do a quick recap.
The sun is a really old, large, hot star. It is the center of our solar system and all the bodies in this system orbit it. The sun provides us with both light and heat and allows humans and other living organisms to survive. In the end, it’s a very impressive star that I’m glad to have around!
Most of my information came from NASA’s Solar System Exploration site. Unless otherwise mentioned and cited, the information is from that site.