Our nearest star, the Sun, lies roughly 93 million miles from the Earth. Having a diameter of 880,000 miles it is 100 times the size of Earth. Over a million Earth-sized planets could fit inside it. It’s the largest object in our Solar System, but it pales in comparison to many of the stars in the night sky. Betelgeuse, for example, is 700 times the size of the Sun. If we were to replace our Sun with this giant, its surface would extend past the orbit of Mars.

The Sun generates heat and light, as well as an entire spectrum of electromagnetic radiation, by fusing hydrogen atoms together to form helium. This process is known as fusion. When the hydrogen atoms fuse they lose a tiny fraction of their mass. This mass is converted into pure energy. This energy is released in a pulse called a photon. These photons make the trip to Earth in about 8 minutes. However, when the photon is created in the core of the Sun it takes thousands of years to reach the surface of the Sun. The best analogy I can give is a person trying to exit a room that is filled with people. Likewise, the atoms in the Sun are very tightly packed together and the photon will continually bump into atoms literally trillions of times before it makes its way to the surface.

The surface of the Sun is very hot reaching 11,000°F. This is cool compared to the core that has a temperature of 27 million degrees. This is the temperature at which hydrogen will fuse.

As we look at the surface of the Sun it seems smooth. Nothing could be further from the truth. The surface of the Sun is a boiling, churning plasma that sends charged particles for hundreds of millions of miles. These particles are called the solar wind. As those particles reach Earth they are funneled toward the poles of the Earth by its magnetic field. These charged particles excite the gases in the atmosphere and they glow. This is the cause of the Northern Lights. Also, streams or jets of this super-heated material are blasted into space producing potentially damaging solar storms. If these storms are intense enough and hit us directly enough our power grids, as well as satellites, could be damaged. For this reason, scientists monitor the Sun’s activity in order to determine the potential for damage.

Fortunately, the Sun has a tremendous amount of fuel (hydrogen) left to convert into helium and energy. But a time will come when all that fuel has been depleted. That’s going to be a very bad day for Earth. The Sun will swell up to a hundred times its present size and likely engulf Earth. Not to worry….this is not going to happen for a very, very long time, or several billion years.

Please feel free to contact me at mwyatt@comancheisd.net if you have any questions. I may not know the answer, but I will try my best to find it. I will respond to your email and hope to be able to post your question and the answer in the Chief.

Marty Wyatt

Astronomy Teacher

Comanche High School

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