The discovery of a planet forming around an infant star in the constellation Taurus offers a unique glimpse of a solar system under construction. Dan Watson, an astronomer at the University of Rochester, used NASA’s Spitzer Space Telescope to study a disk of dust circling the star, which is only a million years old. A sharp-edged hole in the disk indicates that the material there has already contracted into a planet. Traditional models predict this process should take tens of millions of years.
The Spitzer observations also show that dust particles around neighboring young stars in Taurus are coated with significant quantities of water ice and frozen organic molecules. Astronomers have detected such icy particles before, Watson says, “but what’s new here is that we’ve seen them as definitely belonging to the proto- planetary system we’re looking at.” The dust grains there have thicker layers of ice than those found in other parts of the galaxy. Comets, asteroids, and small planets forming from the grains would sweep up lots of water and organic material, illustrating how new worlds could acquire the building blocks for life.