hi guys, i have a question about the orbit-spin relationship of the celestial objects. for example in our solar system i understand the orbital period becomes lengthy for the planets more distant than the sun, it's logical, but what happens with their spinning motion..? i don't understand why Mercury spins for around 175.97 days and Venus for 243 days while earth for 24 hours! and mars for somewhat more than 24 hours!! why does they differ so abruptly in spin ? also someone plz explain me tidal/gravitational lock...