Curious children: What is heaven?

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What is heaven? – Pearl, 12, Regina, Sask.

What is the sky really? It’s interesting because the sky can be so many different things to us: it can be big, beautiful and blue or gray, cloudy and rainy. It can also be full of stars or full of orange and red clouds at sunset or sunrise.

The reason why the sky can do so many different things is that what we experience as the sky are actually just different behaviors of the massive layer of gas above our heads. That layer, which we call the atmosphere, is glued to our planet Earth by an invisible force called gravity, and we are at its bottom. And depending on the time of day and the conditions in the atmosphere, we will see different things.

As an astrophysicist, I am particularly interested in the sky, because it is my job to learn about the different things we find there. I remember the first time I looked at Saturn through a telescope. Usually, when you see Saturn in the sky with your eyes, it looks like a bright star – but when you look at it with a telescope, suddenly it’s a completely different world! It amazed me that it simply hung out in the deep vastness of the universe: I had to learn more.

Bright blues and night stars

You have probably noticed that the sky is especially different between day and night, and the reason for that is the sun.

When it is given to us, the side of the Earth we are on is facing the sun, which means that the incredibly strong light that the sun creates enters our atmosphere. Sunlight is made up of all the colors of the rainbow from red to blue, and our atmosphere is especially good at scattering blue light. This means that when sunlight hits the atmosphere, most pass straight, but blue light bounces off everywhere! So as we sit under our layer of gas, the atmosphere, we see a lot of blue light coming from all directions.

Sunset in pink, yellow, blue and orange
Sunlight is made up of all the colors of the rainbow from red to blue.
(Unsplash / Quino Al)

At night, however, the story is different: the sun is hidden behind the Earth, which means that our atmosphere has no sunlight. This makes our atmosphere mostly invisible, and we enjoy the beautiful sky full of stars.

This is the sky I am really looking forward to.

It helps us and protects us

But that’s not all heaven is! It is both the air we breathe and our protection from space. With each breath, you inhale a little atmosphere into your lungs. Without it we could not survive! And it is precisely that gas that you draw into your lungs that is exactly the same gas that is responsible for scattering sunlight blue light so that our sky is formed during the day.

The light we see with our eyes is just one kind of light in the universe. There are also X-rays (which we use to look at bones and teeth), ultraviolet (UV) light, microwave ovens, and radio light (which we use to communicate). But we have to be careful, because high-energy light, like X-rays or UV light, can be very harmful!

For example, the sun creates a lot of really intense UV light that would burn us very easily if given the chance. But the atmosphere helps! Our atmosphere is full of a very precious gas called ozone that works really well by absorbing sunlight UV and preventing us from burning.

The atmosphere is also great in burning small and medium meteors. If we didn’t have an atmosphere, space rocks the size of a car or a bus would simply hit the ground. Our atmosphere, on the other hand, acts like a bulletproof vest, burning these potentially dangerous objects before they fall to the ground.

An astronaut in a space suit floats
Our atmosphere is a large huge layer of gas with a lot of different movements.
(Unsplash / NASA)

Important, but it stands in the way

The funny thing for astrophysicists is that no matter how important the atmosphere is to us, it actually interferes with what we are trying to do! Let me explain: have you ever swum to the bottom of a pool, looked toward the surface, and tried to discern what was going on above the water? It is hard! This is because the layer of water above you is constantly moving and changing, which constantly distorts things above the water you are trying to look at.

Something very similar is happening on Earth as we look through our atmosphere at the stars in the night sky. Our atmosphere is a large huge layer of gas with a lot of different movements, and we earthlings place telescopes at the bottom of that layer of the atmosphere, trying to look through the turbulent atmosphere towards cold things further.

That is why we place telescopes on the tops of mountains; there is less atmosphere above us! The ultimate way to get around this is by launching a telescope into space, like the Hubble Space Telescope or the James Webb Space Telescope that will be launched soon.

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