The Galactic Equinox / Alien Molt Phenomena

The Galactic Equinox occurs when all of the planets become aligned with their star. When this alignment occurs every alien living off their home planet undergoes a horrible, hideous molting which disfigures them until the equinox is over. It seems from the picture below that the planets in question form a system very similar to the solar system the Earth is in so it's not immediately clear of each solar system throughout the galaxy has their own galactic equinox or if one system causes the molt in all creatures through all the universes.

What IS known, though, is that the molt itself is pretty gross. We can see the beginning of the molt below on Zim to the left and the full extent of the molt to the right - after showing minor signs of skin irritation for most of the day at the time of the equinox Zim literally explodes into a giant mass of green slime.

Fortunately for Zim (and everyone else at MacMeaties that day) the equinox itself only lasts for a minute or so and Zim promptly returned to normal before anyone was suffocated. It lasted just long enough for him to be fired, in fact, thus saving the Earth from tyranical fast-food based Irken overlordship.