Space Speed

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So, a car against asphalt it’s pretty easy determinining the speed.
But when someone says a spaceship, for example Voyager, travels at about 61.5 kkm/h. What speed are we comparing against? According to Google, Earth rotates at the equator at about 1.5 kkm/h. So if we said that we compare Voyager speed vs Quito speed and assuming angle of Voyager vs Quito is 90 degrees then that should be +- 1.5 kkm/h?
And Earth itself is also according to Google running around the sun at a clip of about 107 kkm/h so that would mean that at some points Voyager is doing -40 kkm/h vs Earth.

Just standing “still” in the Universe some shit would be moving really really fast compared to me so where do we flip reference points?

edit: lost a couple of ks

In: Planetary Science

7 Answers

Anonymous 0 Comments

For all but a very few man-made things, the reference is going to be what it’s orbiting about. This is most often Earth, but can be the Sun, or another planet.

But you have asked about one of the exceptions — Voyager. Since they are above the escape velocity from the Sun, aren’t in orbit around the sun. Non the less, I suspect the speed is in reference to the Sun since we tend to like to think our solar system is somehow exceptional.

Since the Voyager spacecraft now basically in interstellar space, referencing their speed to the center of our galaxy might be more appropriate:

https://astronomy.stackexchange.com/questions/53615/space-travel-relative-to-solar-systems-movement-through-space#:~:text=The%20Voyager%20spacecraft%20are%20pretty,the%20center%20of%20the%20galaxy.

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