Question

what size does the earth appear from there​

Answer 1

Answer:

that Earth can be seen only from the near side of the Moon and would always be invisible from the far side. The Earth is seen from the lunar surface to rotate, with a period of approximately one Earth day (differing slightly due to the Moon's orbital motion).

Answer 2

Earth's angular diameter (1.9°) is four times the Moon's as seen from Earth, although because the Moon's orbit is eccentric, Earth's apparent size in the sky varies by about 5% either way (ranging between 1.8° and 2.0° in diameter). Earth shows phases, just like the Moon does for terrestrial observers.