Thanks for the comment!

I tried to fix the eyes. I don't really know how to add the shades without ruining the portrait, but I will try.

Looks good; the eyes are really big though.

There are some shading subtleties in the original that you might try to get: the shadows under the lower lip, under the left nostril, on the whole right side of the face.

I didn't know who this guy was, even though I have a strong interest in astronomy. Shame on me.