This variant is a consequence of another hobby I used to do involving Astrology. The planetary symbols are called glyphs which I dutifully memorized and matched to the planets and (and asteroids) in our solar system. They are listed above for your convenience. I used the Hamburg Symbols (True Type) Font to produce the glyphs.
Although it is arguable as to whether Pluto can be considered a major planet, I have no wish to diminish its importance to astrological interpretation. Scientists seem to have a consistent track record of saying one thing and subsequently changing or contradicting their original statement. There’s always a reason. I’m just waiting for the next reason (in 2015) to reinstate the planet.
As usual in these kinds of Sudoku variations, each symbol represents one of the non-zero units digits. You can first transcribe it to numbers or further flex your mind and solve it as is.