Let’s focus on the sun this week!

Many of us look at the sun but few of us ask questions about it. Questions like: If it’s a ball of gas, why can’t we see through it? Where does all that heat come from? Is it really made of cheese? Oops! - wrong heavenly body.

Well, let’s start with where the energy source is. We know from experience that most hot things cool down when left alone by themselves. Take a red-hot poker out of the fire and set it aside and it cools down.

So why doesn’t the sun cool down? How does it stay hot? The same way you do. It has its own internal energy source. Only the sun doesn’t consume fuel to heat up, as we eat food and metabolize it. The sun fuses for its energy.

Way down deep inside, at the center of the sun called the core, the temperatures and pressures are intense to say the least. There, little hydrogen nuclei – the most prevalent element in the sun by far – get crammed so close together (high pressures) and move so fast (high temperatures) that they do things there that they would never dream of on earth.

These tiny little critters actually smash into each other and stick, in a series of events called fusion, producing helium as they do. But here’s the real important part: As they fuse, some of their mass turns into energy! I kid you not!

According to Einstein’s Special Theory of Relativity, mass and energy can be turned into each other. And that’s what’s happening in a fusion reaction, mass becomes energy.

The sun fuses about 600 million tons of hydrogen every second! About 4 million of those tons become pure energy. The rest becomes helium.

But the energy doesn’t now just have a free ride out of the sun, no siree bob!

Remember the pressure is intense, the atoms there are packed tight, so the newly formed energy- in the form of photons – doesn’t get far before being absorbed by some other particle. But not to worry! It gets re-emitted immediately in some random direction! But only to be reabsorbed again!

This process repeats itself countless times. The photon though, because of pressure differences, finds it easier to move gradually out towards the edge of the sun. But you’ll never believe how long it takes to reach there.

That lowly high-energy photon created way down in the core bounces about for millions of years until it finally gets its release papers!

This is why we cannot see through the sun. There is just too much stuff there absorbing light. But then why and when and where is the little packet of energy released???

If you could travel from the intensely hot, high-pressure core of the sun to its outer layers, you’d find the pressures getting lower and lower and lower. That means the “stuff” is packed less and less and less tightly.

A photon finally gets to a part of the sun where there is… nothing... blocking… its… path! Why, it suddenly finds that it is free to leave. And leave it does!

This release zone on the sun is called the photosphere. It is what we normally refer to as “the sun.” The big yellow ball we see up there is merely the first layer that allows light to flow out. There are actually layers above that – the chromosphere and the corona – but they are mostly invisible to our eyes except during an eclipse. And although those “invisible” layers are legitimate parts of the sun, for most of us “the sun” ends at the photosphere.

Now that the photon is free to leave it races out into space at about 186,000 miles a second.

Sadly some of these photons, after spending all that time making their way through the sun, break free, and just a little over 8 minutes of freedom later find themselves approaching a blue-green-white planet. They race through the atmosphere and in an instant are annihilated as they crash… onto your head.

The same thing happens in stars tens or hundreds of light years away. Their photons struggle to get through the stars. They finally break free, spend a couple hundred years racing through empty space, only to crash into the back of your eye, sending a message to your brain. And you elicit the response, “What a pretty star!”

C’est la vie, little photon.