FINALLY! Found the episode.
Superman: Little Girl Lost Part 2
http://www.tubeplus.me/player/1351661/Superman/season_2/episode_28/Little_Girl_Lost%3A_Part_2/%22
Meteor clip "feat" starts at:18:20 and ends at: 19:23
Some things to consider:
1) At 14:06 Darskeid mentions that the "dark cloud" or the dust cloud caused by the impact and not the impact itself will wipe out all life on Earth. It probably won't wipe out ALL life on earth. As DS is known to hyperbole a lot in this series, I would consider this meaning that he means 70%-90% of all life and ALL intelligent life on the surface.
2) At 18:00 Granny Goodness mentions that the comet is about to enter Earth's atmosphere w/c means that it's been caught in the planet's gravity as well (w/c adds to the feat).
3) At 18:12 Superman mentions that he will "try to deflect" the comet and from how the comet was stopped, it looks like this was the case (it takes a LOT less to deflect something than to push against something).
4) Size comparison between Superman and the comet would put the comet no larger than maybe a large/skyscraper or city block. I find that silly, however, as, scientifically that would not cause an ELE and would much rather base it on the minimum size for such an event. From a google search, I'm estimating the size of about no more than a 5km radius (the same size as the one that was theorized to have wiped out the dinos) moving at high speed.
5) Comet breaks apart @ 18:42, making it even smaller when he deflected it (he was slowing it down, however and slowly moving it from its flight path).
6) Another impressive "feat" is where Supergirl shattered a third of the said the comet @ 19:12. The size of the explosion above Metrolpolis, however, didn't seem so big so I dunno...
Well, that's the feat. Take from it what you will, impressive, yes. But hardly moon sized or anything. 🙂