What is the Sun made of? And other burning questions!
Here we are on Earth, the third rock from the Sun. But how much do we really know about the bright light at the center of our solar system? Some of these facts are simply sun-believable!
The Sun’s warmth is vital to all life on Earth. Ancient people used the Sun’s rising and setting to predict seasonal changes for the harvest and even erect temples. But what is the Sun made of? How does the Sun shine so brightly? And will it burn forever?
1. What is the Sun?
The Sun is a star! It’s one of 100 billion stars in our Milky Way galaxy. It’s a big, round, glowing ball of hot gas.
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The Sun is not an especially large star. It’s of average size. A star such as Betelgeuse is about 900 times the size of the Sun. However, the reason that the Sun appears so much brighter than other stars in the night sky is because the Sun is at the center of our Solar System. Eight planets, asteroids, and comets rotate around the Sun.
“The Sun, with all those planets revolving around it and dependent upon it, can still ripen a bunch of grapes as if it had nothing else in the universe to do.” –Galileo Galilei
2. What is the Sun Made Out Of?
The Sun is composed of plasma, a material made from electrically charged gas atoms. It is about 70% hydrogen gas and about 28% helium. Carbon, nitrogen, and oxygen make up 1.5%. The remaining traces are tiny amounts of metals such as neon, iron, silicon, magnesium, and sulfur.
The shining glow that emanates from the Sun comes a huge amount of energy created from a process called nuclear fusion, which happens in the Sun’s very hot core. During this process, hydrogen converts into helium.
Over time, the Sun will have less hydrogen and more helium. It will take about 5 billion years for the Sun to run out of fuel for nuclear fusion and stop shining.
2. How Old is the Sun?
Scientists estimate the Sun is about 4.6 billion years old, or approximately halfway through its life cycle. The Sun will continue to live on the hydrogen in its center for a few billion more years with its temperature and size staying about the same—so, no surprises in our lifetimes!
When the Sun eats up its nuclear fuel, it will start to collapse. As it compacts, the Sun will generate enough heat to conserve the remaining hydrogen in its outer shell. This will cause the Sun to inflate and “puff up,” turning the star into a red giant.
As the Sun runs out of hydrogen, it will start consuming helium which it transforms into carbon and other heavier elements. The heavy core will contract from gravity, resulting in a huge outward release of energy. What will remain is a dense, small core called a white dwarf surrounded by a huge gaseous envelope called a nebula.
Eventually, the white dwarf will completely cool, blow off its nebula, and fade into black lumps of carbon. The Sun will quietly become a black dwarf, producing no heat nor light.
Did You Know? Only very heavy stars weighing more than a half dozen stars can become a black hole. Learn more about black holes.
3. How Far Away is the Sun?
The Sun is about 93 million miles away from Earth. The distance changes during the seasons because Earth’s orbit around the Sun is not perfectly round but elliptical (like a stretched-out circle). In the Northern Hemisphere, the Sun is nearest during winter (91.4 million miles) and farthest during summer (94.5 million miles).
You may have assumed that the Sun would be further away in winter and closer in summer, but it’s the opposite. Why? See what causes the reasons for the four seasons.
4. How Big is the Sun?
The Sun is about 865,000 miles in diameter—as wide as 109 Earths placed side by side! It contains 99.86% of all of the mass of the entire Solar System and weighs about 333,000 times as much as Earth. In terms of volume, about 1 million Earths would fit inside the Sun. Yes, the Sun is enormous compared to Earth!
5. How Hot is the Sun?
The Sun’s temperature varies over time and through its eight layers. Interestingly, the temperature doesn’t rise in order from the outermost to the innermost layers. It’s coolest at the surface of the Sun (photosphere) at 10,000°F. The Sun gets hotter and hotter as it reaches the inner core, about 28 million°F. But also, the temperature rises from the surface as it radiates outward. The outermost layer (corona) reaches temperatures of millions of degrees.
- Core: The hottest part of the Sun is the core, at 28 million°F, on average.
- Radiative Zone: The second layer becomes cooler and is where photon particles carry energy in all directions through a process called radiation.
- Tachocline: A thin third layer, the tachocline acts as a border between two differently rotating zones.
- Convective Zone: The fourth layer is a zone of boiling, bubbling plasma that transfers energy outward through a process called convection.
- Photosphere: This is the surface of the Sun! It’s the sphere of light that we see from Earth, and where sunspots appear. Temperatures average 10,000°F.
- Chromosphere: The sixth layer is where the temperature begins to rise again. A thin, reddish layer, the chromosphere is seen only during eclipses or with special solar-viewing equipment.
- Transition Region: The layer between the hot corona and cooler chromosphere
- Corona: The eighth and outer layer of the Sun gets extremely hot, measuring 1,800,000°F more. This layer extends far into space and is shaped by the Sun’s magnetic field, is visible only as a bright halo of light during a total solar eclipse.
6. Does the Sun Spin?
Yes. The Sun moves ver-r-r-y slowly! The Sun spins or rotates on its axis in the same direction as Earth (counterclockwise, when looking down from the North Pole).
Because it is a gas, the Sun does not rotate like a solid. Different sections rotate at different speeds! The Sun actually spins faster at its equator than at its poles.
- At the surface, the area around the equator rotates once about every 25 days.
- The Sun’s north and south poles rotate more slowly. It can take those areas more than 30 days to complete one rotation.
We know this by watching the motion of sunspots and other solar features move across the Sun. The giant gas planets, Jupiter, Saturn, Uranus, and Neptune, also spin faster at their equators than at their poles.
7. Why Do Planets Orbit the Sun?
The Sun has a lot of pull! It makes up more than 99% of the total mass of the solar system.
Because it is so massive, the Sun exerts a lot of gravity, or pull, on the planets—enough to cause them to orbit around it. If the planets were not moving forward fast enough to balance the Sun’s sideways pull, they would fall into the Sun.
The Sun’s gravity is about 27.9 times that of Earth, and, in a small way, it helps to control the tides on Earth.
8. Does the Sun Orbit Anything?
Yes! The Sun is the center of our solar system, but it doesn’t stay in one place. It orbits around the center of our Milky Way Galaxy, which is a spiral galaxy. It’s located about two-thirds of the way out from the center of the Milky Way, which is about 28,000 light–years away. (A light-year is about 5.88 trillion miles.)
And it’s not just only our Sun orbiting. Our entire solar system—which contains our Sun, planets, Moon, asteroid, and comets—orbits the center of the Milky Way.
9. How Fast Does the Sun Move?
The Sun is traveling at a speed of around 225 kilometers per second (or 503,311 mph). Even at that high rate, it takes the Sun about 230 million years to go around the galaxy once! One journey around the Milky Way galaxy is sometimes called a cosmic year.
10. How Much Energy Does the Sun Produce?
The Sun is a massive ball of energy. It’s hard to imagine the enormous amount of energy the Sun produces. Because its core is under a lot of pressure, hydrogen atoms constantly collide at great speeds, fusing together to form helium, and releasing energy. Lots of these collisions occur, creating a ball of energy.
In just one second, the Sun produces about 118 times as much energy as the United States uses in a year. Every 1.5 millionths of a second, the Sun releases more energy than all humans consume in an entire year, according to NASA Space Place.
Only about one billionth of the total energy the Sun produces reaches Earth, but it is enough to enable us to live here.
11. Why Does the Sun Have Spots?
As the Sun spins, its magnetic fields get twisted and poke through the surface. When this happens, it prevents the heat rising inside from coming through, creating sunspots. As a result, the Sun’s surface in these areas is cooler and darker than its surroundings, although still very bright.
Sunspots, like storms, aren’t permanent and can range in size. They can last for days or weeks. Learn more about sunspots.
Credit: Grisha Bruev/Shutterstock
12. When Does the Sun Rise?
The time the sun rises, and sets will depend on the time of year and your location. Check out our Sun Rise and Sunset Calculator for personalized data.
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