Astronomy: Before Space

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Image received from Earth Science by Tarbuck and Lutgens

The basics of astronomy start from our own planet, Earth. Our planet has been instrumental in understanding how outer space works so it is critical to get a simple understanding of our planet. Step 1 is the atmosphere. The atmosphere is essentially what we see when we look up, and it has multiple intersecting layers. The image above is really useful in understanding how the atmosphere works. I recommend reading the book in it’s caption to learn everything there is about Earth. Eventually I will have a blog on Earth Sciences also.

The atmosphere has 4(5 to some) main layers. The term layer is loosely used to describe a slice of the atmosphere that has similar properties. Layer 1 is the troposphere, so named because the phrase tropos means change(all of the layers end with sphere because sphere means realm, or region, that is why atmosphere is region of air(Atmos)). The change in troposphere means the fact that all weather occurs in the troposphere, so it is not constant. We see things like clouds in this region which goes vertically up 6.214 miles(10 kilometers). This is equivalent to 32809.92 feet, for perspective. When you are in a plane, you are in this region since planes fly at about 5-8 miles up.

After the troposhere comes the stratosphere, where stratos means layer. This shows that their is really not much happening in this layer except this is where the ozone layer you may have heard of exists. The ozone layer is a layer of trioxygen(3 oxygen) gas that prevents radiation from abundantly hitting the surface.

The next layer is the mesosphere, named such because it is the middle(meso) layer. In this layer, the air is very thin but the last layer to have mixed air(the gases like Nitrogen and Oxygen that make up the air are dispersed) but still exist. This is where you see meteors burn up, what we call shooting stars! This layer goes up to 80 kilometers. The top of the mesosphere is extremely cold(the coldest part of the atmosphere).

Finally we have the thermosphere(and some split the top of the thermosphere to the ionosphere, but I am not going to do that and discuss them as one). This layer starts at 90 kilometers and extends into outer space. We have nearly reached the stars! In this layer, air is extremely thin and separated based off different chemicals(why they split is a little complicated but has to do with reactions to UV radiation). This layer has extremely hot particles(1000 degree Celsius) but since the amount of particles are so little, it would not feel hot. This is the layer that produces the Auroras we have seen in photos(Northern and Southern Lights) because the UV radiation excites the ions in this sphere causing them to give off light as they relax. I’ll talk about how stuff like that works in a chemistry blog.

For Educators:

You can do a short presentation on the different layers of the atmosphere, but more importantly, teach students how air density/pressure decreases with altitude. Remember this is caused by having less particles of air at the higher altitudes. This can also be shown by being cold(if something is cold it means the particles are sparse and/or slow). For inspiration, check out this YouTube video

Thank you!

That is about it for this blog! We have launched off from Earth and have reached outer space. I will see you in the next blog. Contact me with comments at!