What happened during the 1000 years Luna was trapped on the moon? How did she survive all alone?

Upon the surface of the moon there is seldom light and no companion to be found. So as Celestia scrambles to undo the magic of the elements of harmony to return her sister Luna slowly finds herself walking down a path, her shadow as her only friend in the world.

1000 years is a very long time to be alone with your grief and your woes,

On the moon their is no glow
only a world of ice and snow