The Sun is a huge, glowing ball of gases at the center of the solar system. The Earth and the other eight planets travel around it. The Sun is only one of billions of stars in the Universe. As a star, there is nothing unusual about it. But the Sun is more important to people than any other star. Without the heat and light of the Sun, there could be no life on Earth.

The Sun looks big and bright to us because it is not very far away. It is only about 93 million miles (149.6 million km) from Earth. That sounds like a great distance, but compared to the other stars in the sky, the Sun is only a short distance away. The next nearest star to us, Proxima Centauri, is more than 265,000 times as far away.

Stars are glowing balls of gas. Our star, the Sun, is a huge ball, 863,700 miles (1,390,000 km) in diameter. It is so large that if it were empty, you could put 1 million planet Earths inside it. The Sun is also very heavy. If you could put the Sun on one side of a gigantic seesaw, you would need 333,000 Earths on the other side to balance it.

The Sun is a complicated world of seething hot gases and erupting magnetic storms. It has a gigantic atmosphere.  It blows winds of electrically charged particles out beyond the orbit of Pluto, the last planet in the solar system.

Hyrdogen and helium are two main gases that make up the Sun.   Hydrogen is one of the elements found in water. Helium is the gas sometimes put into balloons to make them float.

About 90 percent of the atoms in the Sun are hydrogen atoms. Most of the other 10 percent are helium atoms. Without the pull of the Sun’s strong gravity, these gases would escape into space. The Sun’s gravity pulls the gases close together toward the center of the Sun. The gases become very compressed and very hot. At the Sun’s center, the temperature reaches more than 27,000,000^o F (15,000,000^o  C). The pressure is so great in the center that the gas is squeezed to a density that is more than ten times greater than that of iron.

The combination of high temperature and great pressure triggers an important reaction called fusion. Fusion is the process that makes hydrogen bombs work. When fusion takes place, the Sun’s hydrogen atoms join together and become helium atoms. Tremendous amounts of energy are released.

Because the Sun is so dense, that energy can take millions of years to escape beyond the Sun’s surface. When it does escape, the energy travels through space as light. In only 8 1/2 minutes, the energy reaches Earth, where it lights and heats our world.

If you do glance at the Sun or look at pictures of it taken with solar telescopes, the part of the Sun you see is called the photosphere. The photosphere is the surface, or skin of the Sun. It is made up of gases that are about 10,500^o F (5,861^o  C)..

In some areas of the Sun’s surface there are cooler pools of materials. They do not give off as much light as other hotter areas. Viewed from Earth, these pools appear dark. They are called sunspots. Sunspots can be from 600 miles (966 km) to thousands of miles wide. Mysteriously, every 11 years or so, the magnetic activity on the Sun seems to peak. At that time, many more sunspots are visible.

Even stranger than the sunspots are the spicules, flares, and prominences. Spicules are spike-shaped storms that blast thousands of miles up into the Sun’s atmosphere. Flares are powerful explosions that shoot long streams of electrically charged particles into space. Some flares give off as much energy as 10 million hydrogen bombs exploding all at once.

The most spectacular events on the Sun are the prominences. Millions of tons of hot, glowing gas are blasted hundreds of thousands of miles upward. The glowing gas forms arch-shaped ribbons in the Sun’s magnetic field.

How long will the Sun last? Like all stars, the Sun will eventually vanish.  The fusion process inside the Sun converts about 4 million tons of matter to energy every second. In about 5 billion years, the Sun will have used up most of its hydrogen fuel. Eventually, it will expand hundreds of times and become larger than the orbit of the Earth. Then it will swallow up its solar system and become a red giant star. For a time, it will pulsate and shed shells of gas into space. The remains of the Sun will then condense into a tiny, very hot white dwarf star. Gradually, it will cool and become a dark cinder in space.

The end of our Sun is hard to imagine, but it isn’t something to worry about. The Sun will be with us for several billions of years more.

Sun Facts

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