Complex sentence: In the year 2003, a comet designated Apollon collides with the planet Venus and disperses much of the planet's atmosphere, adding enough moisture to form acidic seas, and speeding up its rotation to give it a day that matches its year.
Split into simpler sentences: In the year 2003, a comet designated Apollon collides with the planet Venus. This has the effect of dispersing much of the planet's atmosphere, adding enough moisture to form (acidic) seas, and speeding up its rotation to give it a day that matches its year.