Hmm. I think I post by pixels. For example, this artwork looks large on the forum but it's
as for the image size, it doesn't enlarge them. Pixels are pixels, it doesn't add or subtract any. Keep in mind that standard web formats are only 72 DPI, so if you are working in say 300 DPI for printing purposes, that's going to look huge on the web, so you'll want to save a separate appropriately sized copy for web posting. Always post based on pixel dimensions, not by 'inches' because inches are used as part of a DPI or PPI ratio.
Thanks for the comment.
As for the image itself, overall it's nice, but the hill feels very flat, and i don't understand why the meteorites and the ground lighting are the same color. I also don't really understand why the whole figure is rimmed in that color as well. You may also want to consider making the shadows a bit more blue, since the clouds seem to be throwing off an awful lot of light and color,yet your shadows don't reflect that color at all presently.