Answering Questions That Kids Ask Me About Aerospace Engineering that I was Definitely Never Taught But Now Know

Why is space black?

Well first lets talk about what we do know, why is the sky blue. The sky is blue because light from the sun hits molecules in Earth’s atmosphere and scatters off in all directions. Blue light is scattered more than other colors because it travels in shorter, smaller waves. At night, the sky looks black because there is no bright source of light like the sun to be scattered.

Therefore, space is black because there is nothing to scatter the light to make it visible.

What would happen if I went into space without a spacesuit?

The g-rated version is that you would pass out, and then die from lack of air in space.

The pg- version is a little more complex. Lets start with a short analogy. When you open a can of soda, there are bubbles at the top right? That is because gasses dissolve under pressure, but when you open the bottle, it releases the pressure and they undissolve again.

When you go from one pressure area, like inside the space station, to another significantly different pressure area, like outside in space, that same phenomenon happens to your lungs. Therefore, if you went outside in space and you held your breath, holding that pressure in your body, your body would balloon up twice in size due to the oxgyen. So my biggest advice is to not hold your breathe if you’re out in space without a space suit. Due to oxygen reserves in your body, you will last about 15 seconds til you pass out.

The next chain of events you cant do much about. In a vacuum like space, liquid evaporates, because the boiling point of any liquid drops with pressure. Therefore, any exposed liquid on your body will vaporize, meaning that your tongue and eyes will boil. Without air in your lungs, blood will stop sending oxygen to the brain. You will die from a lack of air, and then over time your body will freeze.

How big is the sun?

The sun is 109 times wider than the Earth and 330,000 times the mass. To put the with to scale, let us say that Earth’s radius is roughly the width of America (its actually a bit bigger ~1000 miles). This means that the suns radius is 109 times the size of America. That’s huge!

What if we just took oxygen cans up to space and released them?

Great idea! But for that to work, we would need a lot of oxygen, possibly more than we even have on Earth.

On earth, our air is made up of mainly nitrogen, carbon dioxide, and oxygen. This environment has lots of oxygen available around us so we can breathe and live. In space, the air is much less dense. It has mostly some hydrogen and helium, but in much less quantities, so its very spaced apart.

Therefore, we would need to bring up enough oxygen to have a dense air around us to breathe in. But space is so big, that oxygen would naturally spread out, meaning that taking oxygen cans up may not be the best approach.

Why is the moon lumpy?

Well first let’s start with how the moon was formed. Scientists think that the moon was formed from debris blasted into space when a large body slammed into Earth about 4.5 billion years ago. This created a hot molten young moon, trapped in our gravity and rotating around the Earth.

The gravitational forces acting on the moon as it orbits the planet are shown in the figure to the left. This means that overtime, gravity squashes and stretches the moon. This thinned out the crust at the lunar poles and thickened it in regions that lined up with the earth, making the moon like a lemon with two small bulges.

When astronauts do spacewalks, how are they not left behind by the ISS if the ISS is traveling 17,000 mph?

The key here is about the relative speed between the astronaut and the ISS. If the astronaut leaves the ISS, what is slowing it down that would leave them behind? Nothing.

Let’s talk a bit about what it means to get to orbit or to be in orbit. Orbits are a perfect balance between the forward motion of a body in space, and the pull of gravity from another body in space. Think about when you throw a football.


When you throw a ball harder, it goes faster, which means that it goes further away from the building. Now gravity is always pulling the ball down, so the path goes slowly from rightward to downward. Now assume there was no limit on how fast you could throw a ball. Eventually, there is a speed that exists that the ball will miss the Earth in front completely and continue to revolve around the Earth. From this speed, the object is in orbit.

Now lets go back to astronauts in spacewalks. If we know that for something to be in orbit, that it must be traveling at a speed fast enough to stay in orbit, then both the astronaut and the space station have to be traveling at the same speed. When the astronaut exists the space station, they will continue to be at that speed. The astronaut and space station will continue to travel at the same speed as long as neither does anything to change its speed.

(okay i was taught this question)

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