Orbit (not the gum)

 Check out this awesome gravity game, where you can add planets of varying sizes (and other stars) to the orbit - see how many celestial bodies you can get into the orbit without crashing into the outside barrier, and leave your high score in the comments!

You might notice while playing that the closer a planet is to the sun, the faster it goes; that's the fundamental reason that orbit happens: the orbiting object is going fast enough sideways that it never gets any closer to the star or planet that it's orbiting. Check out these gifs:

No sideways motion

Not fast enough for orbit!

The perfect speed!

So the closer an object is to the sun, the faster it has to go to stay in perfect orbit! That's why Mercury is named after the speedy Roman messenger god - a "year" (one full revolution around the sun) on Mercury is only 88 Earth Days! Pluto hasn't even made a single revolution around the sun since it was discovered 77 years ago - Pluto takes 248 earth years to orbit the sun one time.

Only the first 2 minutes of this video are about orbit - the rest is about fusion, which we talked about yesterday :)

Are astronauts in space outside of the effects of gravity? They sure seem "weightless" - but they are closer to the Earth than the moon is, and the moon is kept in orbit by the Earth's gravity...so they are not too far away to be affected by gravity from the Earth. So why are they "weightless?"

Doge has the same misconception that most people do, that there is no gravity in space - there is!

To explore this secret, think about an elevator. When the elevator is going down, if you jump up in the air, you'll fall farther than you jumped right? Because the elevator has lowered while you were in the air. Now imagine if the elevator was faster - you would float in the air even longer, right? What if it were falling at the same rate that you were?

Scary prank! If this happened for real and the elevator fell with you, you would seem weightless compared to the elevator

The astronauts in the space station are constantly falling at the same rate that their spaceship is. The only reason they don't get any closer to the earth is because they are in orbit, so their sideways velocity keeps them going around, instead of falling directly down.