Timeline for How fast could earth orbit the sun without its orbit changing?
Current License: CC BY-SA 3.0
18 events
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| Oct 16, 2017 at 18:39 | comment | added | Logan R. Kearsley | @Cody "The same orbit, but retrograde" is not "the same orbit". And in any case, the ending velocity has the same magnitude anyway, so the result that you can't increase the Earth's velocity and maintain the same orbit still stands. | |
| Oct 16, 2017 at 18:32 | comment | added | Cody | I think there is a single exception to your answer. What if you gave the Earth 60km/s delta-v in the retrograde direction? Never mind the catastrophic damage an impulse like that would cause, if it was in the same orbit but retrograde it should be the same, at least on short timescales. Over millions/billions of years, the chaos of the system might disrupt Earth and other planets, but over a few hundred years it should be unnoticeable. | |
| Oct 16, 2017 at 15:09 | history | edited | Logan R. Kearsley | CC BY-SA 3.0 |
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| Oct 16, 2017 at 10:25 | comment | added | rexkogitans | Think of a ball rolling around the inner side of a funnel. This is exactly what planets do when orbiting the sun. Speed and radius of the ball's orbit in the funnel interact strictly with each other: The closer to the centre, the higher the speed. So the simple answer is: There is no way to change this. To emphasise: The elliptical orbit of the Earth refelcts this too: When the Earth is closer to the Sun, it orbits faster (2nd Kepler's law). | |
| Oct 16, 2017 at 7:57 | history | edited | MichaelK | CC BY-SA 3.0 |
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| Oct 16, 2017 at 5:43 | comment | added | a4android | @chrylis I can read too. However, it's not exactly clear that the velocity mentioned is the Earth's present velocity. I knew that, but I was concerned others might not grasp the point. As I said, I was being pedantic about clarity. | |
| Oct 16, 2017 at 5:03 | comment | added | chrylis -cautiouslyoptimistic- | @a4android The actual speed was included in the question. | |
| Oct 16, 2017 at 3:07 | comment | added | Logan R. Kearsley | @ThorstenS. Why? That's an answer to a completely different, inverted question--this one's about changing speed without changing orbit, not changing orbit without changing speed. And by the way, thrusting perpendicular would change the orbit without changing it's instantaneous speed--as you said, it alters the eccentricity. | |
| Oct 15, 2017 at 22:32 | comment | added | Thorsten S. | @LoganR.Kearsley While correct, you need to explain that the "obvious idea" of pushing the Earth radially outwards does not allow to change orbit with unchanging velocity, but changes the orbit from nearly circular to elliptical. | |
| Oct 15, 2017 at 22:23 | comment | added | Logan R. Kearsley | @Agent_L The trouble is, it isn't "precisely". The Earth's orbit is slightly elliptical, so the Earth's orbital speed does in fact vary a bit above and a bit below 30 km/s. At any given point, it must have exactly one velocity, and changing that velocity will change the orbit; but over the whole orbit, it doesn't have just one velocity. | |
| Oct 15, 2017 at 21:31 | comment | added | Agent_L | I think this answer would be clearer if instead of "about" it used "precisely". "About" suggests there is some wiggle room where there is none. | |
| Oct 15, 2017 at 20:35 | comment | added | Tony Ennis | It is very inobvious. Non-physics people will be challenged with the concept. | |
| Oct 15, 2017 at 15:24 | comment | added | Yakk | @StephenG The rocket engine aims outward, the Earth (the rocket) is pushed inward. | |
| Oct 15, 2017 at 13:57 | comment | added | StephenG - Help Ukraine | @Yakk Adding radial acceleration outward in that way would force the Earth into a spiral orbit away from the Sun while the rocket was active and then a final orbital path (some conic path) after the rocket stopped. To offset the outward radial acceleration you would need to slow down the Earth (not speed it up). To speed up the Earth would require you add force towards the Sun. | |
| Oct 15, 2017 at 5:41 | comment | added | Yakk | If you add a large enough rocket engine to aim outward (from the sun), it could go much faster in the same orbital track. ;) | |
| Oct 15, 2017 at 4:12 | comment | added | a4android | For clarity you might point out the Earth is travelling at 30 km/s currently and this isn't some different or higher orbital velocity. Sorry if I'm being pedantic and trying to point the obvious. | |
| Oct 15, 2017 at 1:11 | vote | accept | Leezard | ||
| Oct 15, 2017 at 0:50 | history | answered | Logan R. Kearsley | CC BY-SA 3.0 |