Planet Building in HD 100546.

More than 100 billion boulders may be swarming in the disk around nearby star HD 100546 . In a scene thought similar to the early years of our own Solar System , ever larger rocks are growing by colliding and accreting dust as the messy business of planet formation appears to be underway. For an Earth-like planet in such a hostile environment, the sky would be lit continuously with streaking meteors and the ground would rumble continuously with impacts . Pictured above , the swirling disk of dust , gas, and rocks of HD 100546 is visible as the dark region surrounding the image center. The bright light and six-pointed diffraction spikes from the central star have been removed from the false-color image. HD 100546 is visible with binoculars towards the southern constellation of Musca , and is a relatively nearby 335 light-years away. Similar planet-building systems, dubbed proplyds , have recently been found in Orion , where many emerging planets there must survive the boiling radiations of neighboring bright stars .