Here is why spacecraft orbits almost look like sine waves on maps.

Here is why spacecraft orbits almost look like sine waves on maps.

Maybe I'm being really really dim but I still have absolutely no idea why spacecraft orbit like sine waves. All I'm seeing is that they go up and down just because they do.

Edit: thanks for everyone's responses! Turns out I am just dim, haha.

ISS orbit

The point of my gif is to show that they are not going up and down. They go in circles around earth and it just looks like a wave when you track them on a flat map. If you'd strech a flat map around a sphere it would become a circle again. Now those maps you know from the internet are not perfectly transformed from a sphere into a rectangle as seen in the video. They warp the map so that the continents look closer to what they look in real life. This makes the orbits look even weirder with flat sections and what not! However, an orbit is always a circle. (There are a few exceptions when for example the moon disturbs an object orbit but generally speaking it's a circle or ellipse). What could be a little confusing in my animation, which I just realise is the earth spin. I just do that to show it from all angles. An orbit always faces the same direction. It does no hula hoop.

edit: I found an old video of mine where I animated the .

video

Ah okay, they have an inclination against the equator (the tilt) so that they also pass over northern and southern parts of earth. If they would only fly over the equator they wouldn't be able to make pictures from Europe or Canada for example. They get more bang for their buck so to speak. Another reason is the placement of the different launch sites. If you want to launch into an orbit which is above the earth equator you had to launch from the equator or do a really hard turn midflight which would be very difficult.

edit: Here an older of mine showing how the ISS passes over land.

Kerbal Space Program really helps one understand orbital mechanics and space travel in general.

I see the circle, but why are they going in a circle like that instead of moving 'with' the planet?

Edit: You're edit's cleared that up a bit, thanks for the explanation!

Spamy McSpamface

cough Some random guy which is totally not me (j/k, it's me) does videos to explain stuff going to space. I always appreciate feedback because I fear I am sometimes too hectic.

That game has a really steep learning curve though. Kind of like a sine wave...

Interesting! I appreciate you answering the questions of a mere simpleton, this helps a lot.

Well it is literally rocket science.

mp4 link



This mp4 version is 77.05% smaller than the gif (1.23 MB vs 5.37 MB).  



Beep, I'm a bot. FAQ | author | source | v1.1.2

This mp4 version is 77.05% smaller than the gif (1.23 MB vs 5.37 MB).

Beep, I'm a bot. FAQ | author | source | v1.1.2

Or to dumb people?

Just curious, what does this mean to smart people?

Definitely not an expert but I'll try. 

Here is a picture of the earth orbit of the International Space Station, represented by what I believe is an equirectangular map projection.

Here is a gif visualizing the sine and cosine waves.

And here is OP's gif. See how they're related?

There are many types of satellite orbits, but when a satellite travels around the earth at some incline from the equator its orbit can be represented by a sine function on a 2d graph. 

Btw, if someone could tell me which specific type of orbit is in OP's post I'd appreciate it.

Definitely not an expert but I'll try.

is a picture of the earth orbit of the International Space Station, represented by what I believe is an equirectangular map projection.

Here is a gif visualizing the sine and cosine waves.

And here is OP's gif. See how they're related?

There are many types of satellite orbits, but when a satellite travels around the earth at some incline from the equator its orbit can be represented by a sine function on a 2d graph.

Btw, if someone could tell me which specific type of orbit is in OP's post I'd appreciate it.

Earth is flat confirmed

Some unsolicited feedback which you hopefully find constructive:

The equator is missing. This would give a firm anchor point for the eye during the transition to a projection and show the sinusoidal nature of the orbital track even better once that transition is completed. It's not super clear when the animation starts if the line near the center is equatorial or not, which leads to a bit of confusion. I feel like it's important enough that I would highlight it by width or alpha vs. the other latitude lines to give the viewer something to focus on.

The globe rotation in the beginning feels a little fast to me, and the unfurling to a flat map a little slow. The rotation really only has to be enough to show whether the rotation of the orbit is tied to the earth's axis, so the excess speed is a little jarring. I'd say that rotation could be 50% slower. As for the unfurling, I feel that we as animators often get too enamored with the neat thing we finally figured out how to do and linger on it a bit too long. The unfurling is very cool, but it could also be a third or half as long and still convey the same message, especially given a better anchor point as discussed above.

That extra time from the transition can go into a longer hold at the end. It's important to give viewers 5 or 6 seconds to absorb or ponder over what they've just watched, and this is more like a second or two before the ending wipe.

Speaking of the wipe, I'd ditch it. It's easier to do that with a mask and render as necessary for the project than to have it in the actual animation.

If this were in a 16:9 ratio, there would be a little less white space at the end, which is especially important now that so much media is viewed on smaller screens. However, the current aspect ratio is probably more suitable for embedding in a presentation or web page, so this one could probably go either way. Once again, I would render the animation in a larger size and crop as necessary to fit format.

You could also add a moving dot to the orbital track, but that may or may not clutter stuff up too much; I'd have to AB it to say for sure.

Anyway, I hope those suggestions help. Take or leave them as you like.

Flat maps make circles look like squiggles, compare with a picture of earth at it is lit by the sun.

Flat maps make circles look like squiggles,

Satellites all have different jobs and are required to pass over different parts of the planet.

Not entirely, you can build space planes too, and some of it is just day to day project management.

Ah, so they're made to do that by humans rather than because of spacey-wacey stuff?

Simpleton? Fuck that, you're curious and asking questions. That's awesome.

They videos are really well done and cover the launch schedule pretty comprehensively. Nice job!

I wish KSP had more launch sites, I know there's mods for it but I think new players would learn a lot more by having launch sites not on the equator. Most people's first experience launching away from the equator is after landing on a different body, and I know I messed up those launches quite a few times before figuring them out.

Play Kerbal Space Program. It's a video game that let's you build ships and send them into... Interactive orbits around planets!

We need reverse gif for this, then it might be more easy . . .

When you realize sin is just a function of a straight constant line on a round object

Scott Manley.

Luckily, there is

The first half of the gif shows a fully circular orbit on a rotating sphere. From this perspective it shows that the spacecraft is just going in a straight line the whole time. When projected on a flat map it looks like a sin wave.