It’s cool to learn more about the sun

It’s sure hot! I haven’t seen any evidence that the sun is cooling down, although I am told that it is only a matter of time before it burns out.

How long that will take depends on how fast it burns. How long it burns depends on what it burns, and how it does so.

I got to wondering about that kind of thing. In spite of the fact that all plants depend on the sun, and all animals depend on plants, the sun hasn’t really been a part of my biological education.

But I did some checking around. Here’s what I found.

The sun burns hydrogen, a gas, at its core, and turns the hydrogen into helium, another gas. This process is called nuclear fusion and produces heat and light. Someone has calculated that the sun burns about 700 billion tons of hydrogen a second. Even though that number is less than our national debt, I still found it pretty alarming until I wrote out the number for the mass of the sun, which is 1,989 with 30 zeros behind it.

That is one million nine thousand, eight hundred and nine billion, billion, billion kilograms. Heck, if that number were our GNP in dollars, we could borrow even more money for a couple of more years.

In comparison, several hundred billion tons of hydrogen isn’t all that much.

So while it’s nice to know that our sun won’t be going out soon, it also means that things probably aren’t going to cool off a lot in the near future.

In fact, before the sun burns out, it is supposed to get even hotter. I guess when the hydrogen is finally all burned up, the sun will begin to burn the helium.

Then the increased heat will make the sun get even hotter and the sun will then expand in size to encompass the Earth, and maybe even Mars.

Some scientists estimate that we only have about 5 billion years left.

They also estimate that in just a billion years before, the sun will get so hot it burns off all the water on Earth, putting an end to Lake Powell and the Moyer Pool. By then it won’t be the heat as much as the humidity.

Apparently, the sun has been burning for quite a while already.

I am sure it has been burning since 1945 based upon my personal recollections. But others, who must be terribly old, tell me that the sun already has been burning for several billion years.

Presently, the sun is called a Main Sequence Star and it will last for another 5 billion years as it is.

But then it will turn into a Red Giant for a few billion years, and finally will become a White Dwarf for about 10 billion years.

I wouldn’t plan my vacation based on the predictions. Prophecy is notoriously difficult.

The truth is a lot of facts about the sun are kind of squishy.

For example, unlike rocky planets, the sun doesn’t have a definite boundary. That makes it a little difficult to measure the actual diameter.

Usually scientists measure the distance from the core to the edge of the photosphere to calculate the diameter.

The photosphere is just the area where the gases are too cool to radiate a lot of light. The sun appears to be losing brightness at the rate of about 0.02 percent per year. How does it do that if it is getting hotter?

I think it’s especially interesting that the energy we feel from the sun actually left the sun about eight minutes and 19 seconds ago.

That knowledge is a little discouraging when I am working in the garden because I know, as hot as it is at that moment, it’s going to be hotter in just a little more than eight minutes.

It’s sure hot!

Gary McCallister is professor of biology at Mesa State College.


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