Snowball Earth brightness The Earth likely froze over almost completely about 700 million years ago. This increased its albedo significantly, and I wonder if that would have a considerable effect on its apparent magnitude from other planets. (The Sun was like 4% fainter, though.)

If so, would the Earth be naked-eye visible from farther away 700 mya than it is now? Maybe from Uranus's moons?
Earth is already pretty bright due to cloud cover, with a typical albedo of .3-.35 -- that is, it reflects about a third of the visible light that hits it.

That means it couldn't get more than about three times as bright even if it were perfectly reflective (albedo 1.0), which means about 1.2 magnitudes brighter.

Spotting Earth from a great distance with the naked eye is less an issue of brightness, more an issue of separation from the Sun. I can't run numbers at the moment to get actual magnitudes or angular separations.