Get to the gravity of the situation

Every once in awhile, I like to go back to the basics. For instance, do you really know what those stars are that shine in the sky night after night?

Basically, all stars are big balls of hydrogen gas, some much bigger than others. Even the smallest shiners that we gaze upon are much bigger than our home planet.

The closest star to Earth is the sun, which is a little more than 93 million miles away. The next closest star to Earth is almost 25 trillion miles away.

No matter how far away they are, all stars are about the same.

So while we know that the sun is a big ball of mainly hydrogen gas, what makes it shine? And why is the temperature of its surface more than 10,000 degrees?


The sun and other stars have nuclear fusion furnaces inside of them, and gravity is what fuels them.

Gravitational pull

Because the mass of the sun is so large, the gravitational field around it is so strong that not only do the planets in our solar system obediently orbit it, the big ball of gas that is our sun is being squeezed by its own gravity.

It’s estimated that this gravitational squeezing of the sun increases the pressure inside of it, to the tune of more than 500 billion pounds per square-inch toward the center. In turn, that drives up the temperature at the sun’s core to an estimated 27 million degrees. That tremendous heat is the trigger for the nuclear fusion furnace.

Nuclear fusion is a tremendously complicated process, but the essence is this: Hydrogen atoms at the core of the sun are moving very fast because of the tremendous heat, forcing tremendous collisions between them. These collisions are so violent that the hydrogen atoms fuse together, creating heavier helium atoms.

In the process, energy is produced, and it soon finds its way to the sun’s surface. By the time this radiation reaches the visible surface of the sun, it’s cooled off to a little more than 10,000 degrees.

It gets a bit more complicated than this, but the gist of it is that gravity is the trigger, hydrogen is the fuel of the sun/star, helium is the ash and energy is the byproduct.

Twinkle, twinkle


Now what about the twinkling of those not-so-little stars? Well, that has nothing to do with the stars themselves, but rather our turbulent atmosphere jerking around the light waves from these stars that are so far away.

The higher the winds are in all levels of the atmosphere, the more the stars will twinkle. That’s why amateur astronomers like to observe with their telescopes on calm clear evenings. The images through telescopes of any size are cleaner and wind chill doesn’t have to be dealt with.

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