Once you get into real science where the Sun and Earth travel through space, either you have some sort of anchor device (meaning you can’t go back before that anchor was made), or it’s proper use of a black hole or some sort of singularity where things like lightspeed travel is already solved, and there’s an established pair of terminus points.
One explanation could be that the time machine is anchored to the 🌞 gravity well, so it can find the position based on where the 🌞 is. In said setting, you’re also limited to only traveling whole years.
Once you get into real science where the Sun and Earth travel through space, either you have some sort of anchor device (meaning you can’t go back before that anchor was made), or it’s proper use of a black hole or some sort of singularity where things like lightspeed travel is already solved, and there’s an established pair of terminus points.
One explanation could be that the time machine is anchored to the 🌞 gravity well, so it can find the position based on where the 🌞 is. In said setting, you’re also limited to only traveling whole years.