hate to say it but filter overuse is very obvious here. that said, I myself suck at photoshopping so take that observation with a grain of salt because I honestly don't know how to help you with that part...however what I can legit say is that the clouds swirling over Earth (?) don't look alive, more dead and just 'there', y'know? google 'earth in space', etc... even the famous 1969 snapshot by Apollo is extremely dynamic, you can actually SEE the earth is ..alive, moving. A cause to this problem on your painting might be due to the dull, almost one-tone blue shade, the texture would not impose life or the idea of rippling tides to me because it seems almost papery like the stuff you see on cardboard paper. Play with the concept of contrasting color schemes. There are light blue and dark blue tones on your Earth, sure, but the transition is too dull to look REAL. like... for instance, in the 1969 snapshot, almost all of the earth is a dark blue but also rich in color and the very bright, almost cerulean shade thinly surrounding the ends of the sphere adds more to the depth. Imagine if that bright tint wasn't there?????? Also, the clouds (!!) on the snapshot on the south pole are very dynamic, has a very rich 'body'. Notice how there are varying thicknesses and shapes?? If it was all one flavor it would have looked very flat and boring. The swirls over the bottom tip of Africa and around gives the general atmosphere (literally) a very alive and moving feel in contrast to your painting. Also, the edges of the geographic plates on your painting show up too much next to the water. I would never advocate the blur tool however I'm fairly sure this could have been remedied some way or the other by making the transition more subtle.
NOTE: I was under the impression the 'blue marble' photo from NASA I referred to was taken in 1969. Apparently it was actually from a 1972 mission.
Also the other reviewer is right. The realism is ruined also by the brightness of the surrounding space. Generally, if taken from the planet's focal point, it would be much blacker and darker especially considering our own planet is more than 4.5 light years away from the closest star excluding the Sun. And please. NO LENS FLARE. It automatically horridly stenches an otherwise potent drawing every. single. TIME.
Not trying to tear ya to pieces though, since this was only the third try right?? I do admittedly like the purple and yellow contrasting with each other, I just don't think it'd be necessarily appropriate in a realistic planet scene.