Credit:
Alt text: An arrow at the bottom of the image indicates the age of the system increasing toward the right of the image from 1-10 Million years, to 10-100 Million years, to greater than 100 Million years. In the middle of the image, at left (1-10 Million years) there is a star surrounded by a disk of gas and dust. A planet is forming in it and migrating closer to the star. At 10-100 Million years the disk is gone and hot Jupiter has already arrived, and is on an aligned orbit. At the top of the figure, there is a planet forming in the disk at 1-10 Million years, but it forms further out than in the bottom panel. There is an arrow spanning the entire 10-100 Million years section. At more than 100 Million years, the planet is on an eccentric, misaligned orbit. A small amount of time later, the planet's orbit is circular and misaligned.