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Billions of years ago, big clouds of gas started clumping together. Gravity made them do it.
As the clump grew, so did its gravity. The stronger the gravity got, the more gas the clump pulled in. The gas packed tighter and tighter, and it heated up. Soon, the heat and pressure got too strong. In a big blast, a star was born. It was our star—the Sun—and right away, it began making energy. Billions of years later, the Sun is now middle-aged. It still pours out energy. It has used up more than half of its fuel, which is the hydrogen at its center. But don’t worry. Our Sun won’t run out of fuel for billions of years. Until then, the nuclear plant in the sky will give us heat, light, and other energy. That energy is what keeps everything on planet Earth alive.
Core
The superhot core is where atomic blasts happen. Hydrogen turns into helium, creating energy. The energy is in the form of gamma rays, which are deadly to humans. The gamma rays begin to rise.
Temperature: 27,000,000°F
Solar flares are sudden blasts of burning gas. They shoot millions of miles into space. The energy they put out is very powerful. Solar flares and sunspots often happen together.
Radiative Zone
In the radiative zone, gamma rays bounce around like pinballs. Many of them turn into less harmful kinds of energy. The Sun is very dense, or thick. Energy takes millions of years to get to the surface! The energy you feel right now was made when Homo erectus lived on Earth. Homo erectus were early humans.
Temperature: 4,500,000°F
Photosphere
The photosphere is the visible “surface” of the Sun. As hot gases rise, they take energy up to the surface with them. The energy escapes through the surface and spreads into space.
Temperature: 10,000°F
Chromosphere
A part of the Sun’s atmosphere, the chromosphere is a layer of gas above the photosphere. In a solar eclipse, the bright photosphere is blacked out. That’s the only time we can see the chromosphere.
Temperature: 50,000°F
Corona
The corona, or “crown,” is the Sun’s upper atmosphere. Like the chromosphere, it can only be seen in a solar eclipse.
Temperature: 4,000,000°F
“If there exists a cosmic ballet, it is among the solar system’s planets as they wander against the background stars with orbits and paths that are choreographed by the forces of gravity.”
—Neil de Grasse Tyson, Universe Down to Earth
▲ This photograph of a solar eclipse was taken in 1905 at the Munich observatory. When do we see an eclipse of the Sun? When the Moon comes between the Sun and the Earth.
▲ A star’s color tells us how hot or cold it is. Blue stars are the hottest and brightest. Stars of medium heat are yellow. The coldest and dimmest stars are red. Our Sun is called a yellow dwarf, even though it’s in the middle range for that size.
Sunspots are dark blotches on the surface of the Sun. They build up in a cycle. About every 11 years, the number of sunspots reaches its highest level. The spots are cooler than the rest of the Sun’s surface. If you can call 7,800°F cool! ▼
▲ Why do solar flares happen?
Flares happen when energy that has built up in the Sun’s atmosphere is suddenly let out. The area bursts in a big explosion.
What happens when the energy of a flare hits Earth?
▲ Astronauts have to land or take cover, because the radiation is deadly. (Earth’s atmosphere protects people on the ground.)
▲ Extreme flares can knock satellites out of orbit. They can even mess up communications on Earth.
▲ During a solar flare, the northern and southern lights become even more amazing. Particles from the solar flare help make the bright colors.
Check It Out!
Mercury is the planet closest to the Sun. What would the Sun look like if you were standing on Mercury?
It would look nine times bigger than it does from Earth. Plus, it would look a little larger and then a little smaller. That’s because Mercury’s orbit is an oval, or ellipse.
