Algodoo

Due to the fact that gravity is stronger the closer you are, Blue's particles closer to the star are pulled in stronger than those farther out, causing the planet to deform into an egg. These are called tidal forces, they are responsible for the tides, and they are also responsible for tearing moons appart if they get too close to their orbiting parents. I coloured all of the particles differently and left borders on to make it easier to see