Not only is the earth never in the same spot, the solar system it's never in the same spot either. Even our galaxy is moving.

Well, I'm glad we got to the bottom of what's unrealistic about traveling back in time...

I don’t remember the name of the novel, so somebody help me with this. The concept is basically that scientists invent time travel, but use it as a teleportation device instead. Set the machine by a few seconds, you teleport the distance covered by the Earth during that time. They even use the technique to plan for an assasination of Kim Jong Un. Loved that one. Some innovative sequences using the ‘time machine’.

Edit: Found it. It's actually two books (original and sequel).

Split Second - https://www.goodreads.com/book/show/26216031-split-second

and

Time Frame - https://www.goodreads.com/book/show/37946554-time-frame

The first book takes its time revealing the 'time travel', but the second book dives head first into using the technology proficiently.

Same spot relative to what? What object do time machines use as a reference for their coordinates? It would make sense to be Earth, so it would be in the same spot all the time.

Well, I am traveling forward in time in home made Time Machine with the speed of one second per second. I do not see any problem you are describing. Now I just need to add the reverse, but I do not expect any issues of this kind either.

In this case, it makes sense to time travel from space and land on a planet upon arrival. Maybe all UFOs are just time travellers after all?🤔

This is why I think time travel will require both an entry and an exit portal, though it’d be through the same device. You’d walk in the portal at one point in time and space, then walk out of the exact same portal at another point in time and space. You’d only be able to travel between points where that time device exists in time and space, you’re using the same portal to travel to a different time in its existence. So no traveling back to the time of dinosaurs or the beginning of time or going to any point past when the portal no longer exists anymore. It’d solve the problem of having to deal with galaxies/stars/planets moving through space and would help mitigate some paradoxes, though not all and maybe even create others.

I thought about something like this when I was a little kid watching Back To The Future 2: "what if the ground had sunken somewhat since that mall was put there and the DeLorean emerged underground?"

Weak premise considering the principles of relativity, and how our current understanding of time travel is basically rooted in SPACE-time.

Nor the solar system, nor the galaxy, nor the universe

I always assumed that teleportation would need to also be present for time travel. Clearly, just an assumption.

But would they be skeletons?

At least this way you get to see space as you die, my worst-case scenario would be time travelling and arriving inside a concrete dam

Semi-relevant Tom Scott (actually about teleportation, but covers many of the same problems)

Nice one 👌

It's amazing how plausible this is

Whenever Earth reaches their orbit they fall down as shooting stars.

*any time

Since the universe is expanding.

Well you can always orient yourself relative to the aether /s