SPOILERS FOR "INDEPENDENCE DAY: RESURGENCE" ABOUND.
I just watch ID:R and had a question about a plot point. In the movie, a large alien ship, which looked to be about 10-20 percent the size of Earth lands/parks on Earth. It's not solid through and through, so its specific gravity wouldn't be identical to the mass per volume of Earth, but it would still have an enormous mass nontheless. Wouldn't the increased mass cause a change in the gravitational pull between Earth and the Sun, and eventually cause Earth to spiral in and collide with our star?
It's hard to say how long the ship stayed on Earth (it left). But would a few hours be enough to affect the gravitational pull and start the inward spiral?