Timeline for If a satellite is put into the same orbit of the Sun as Earth, how does it avoid hitting Earth?
Current License: CC BY-SA 4.0
15 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Oct 8, 2021 at 13:30 | comment | added | PM 2Ring | Here's some old Python code of mine that plots the orbits of several (non-interacting) bodies which pass through a given point with speed v at various angles. They all have the same semi-major axis and hence have the same period.. | |
| Oct 8, 2021 at 12:42 | comment | added | Stilez | Yeah, but its easily misunderstood. Not everyone will pick up on the distinction for example. | |
| Oct 8, 2021 at 12:40 | history | edited | Nuclear Hoagie | CC BY-SA 4.0 |
added 15 characters in body
|
| Oct 8, 2021 at 12:37 | comment | added | Nuclear Hoagie | @Stilez I meant that if you know an object's position and velocity at a single point in time, that is sufficient to define the entire orbit of a free-falling object. If two objects have the same velocity at the same position (at any point in their orbits), their entire orbits must be identical. I'm commenting on instantaneous position/velocity, and not trying to imply anything about mean distance/velocity. My point is also only true for velocity, not speed. An instantaneous velocity and position define an orbit. | |
| Oct 8, 2021 at 7:38 | comment | added | Stilez | I like this, but "An orbit is defined by a position and velocity" feels wrong to me on 3 scores: 1) it implies an independent free choice of both mean distance and mean speed, which isn't the case. 2) you mean speed not velocity, 3) you probably also need to be clear its mean/average distance and mean/average speed, not actual distance and speed. Those aren't necessarily obvious to a reader, but are important to not create misunderstanding. Any chance of editing to improve this point? | |
| Oct 7, 2021 at 17:09 | comment | added | Kuba hasn't forgotten Monica | Nitpick: It is certainly possible to have an arbitrary path that might follow an orbital path, but at an incorrect speed. It just won't be a "freefall" or a free orbit: you'll have to provide constant thrust to counteract the radial forces inherent in a curved trajectory. You could certainly maintain a geostationary location at say 1000km altitude above MSL. Just for not very long before you'd be out of fuel. | |
| Oct 7, 2021 at 9:52 | comment | added | Sebastian Mach | I think it would be nice if this included a short discussion about Lagrange point L3, which could be interpreted as "following Earth", even though half a year apart in period and position. | |
| Oct 7, 2021 at 8:38 | comment | added | Sebastian Mach | @Connor Garcia: If you're going faster, the orbit will be larger, and if you're going slower, the orbit will be smaller. That is a little confusing. On an orbit of large area, one is slower than on a low area orbit. I think what you intended to state was "if you accelerate, the orbit grows". But then again, deceleration is acceleration, too. Maybe we skip that altogether - orbits are too unintuitive when coming from earth life. | |
| Oct 6, 2021 at 18:46 | history | edited | Nuclear Hoagie | CC BY-SA 4.0 |
added 188 characters in body
|
| Oct 5, 2021 at 19:20 | comment | added | James K | I've edited to use something like the wording in that comment. | |
| Oct 5, 2021 at 19:20 | history | edited | James K | CC BY-SA 4.0 |
added 24 characters in body
|
| Oct 5, 2021 at 18:53 | comment | added | Nuclear Hoagie | @ConnorGarcia You're right, I could have worded that better - I meant that accelerating in the direction of travel will put you into a larger orbit, although the forward acceleration will counterintuitively result in a decrease in average orbital speed. | |
| Oct 5, 2021 at 17:03 | comment | added | PM 2Ring | In units of au & years, all solar orbits obey $a^3=T^2$, according to Kepler's 3rd law. So mean $v^2$ is inversely proportional to $a$. | |
| Oct 5, 2021 at 16:50 | comment | added | Connor Garcia♦ | I like this answer, but I think this part of it is backwards: If you're going faster, the orbit will be larger, and if you're going slower, the orbit will be smaller. | |
| Oct 5, 2021 at 15:39 | history | answered | Nuclear Hoagie | CC BY-SA 4.0 |