Hubble Captures Birth of Planets in Cosmic Shadows

The Hubble Space Telescope has discovered two shadows moving counterclockwise across a gas-and-dust disk encircling the young star TW Hydrae, indicating the presence of two misaligned disks caused by the gravitational pull of two planets in slightly different orbital planes. The disks are proxies for planets that are lapping each other as they whirl around the star, and may be comparable to the range of orbital inclinations inside our solar system. The outer disk that the shadows are falling on may extend as far as several times the radius of our solar system’s Kuiper belt, and may have a curious gap at twice Pluto’s average distance from the Sun, which might be evidence for a third planet in the system.