The James Webb Space Telescope will study the formation of giant planets and “brown dwarfs,” dim objects much smaller than ordinary stars. Giant planets may indicate the presence of a process that would also create Earth-like planets; brown dwarfs, because of the conditions required for their formation, would signal systems in which Earth-like planets would be rare or impossible. Webb will try to determine how common giant planets are and how their formation might affect the creation of terrestrial planets.

Scientists believe that the disks of dust and debris found circling certain stars may be the beginnings of new solar systems. Webb will study these circumstellar disks to look for similarities and differences between their composition and the materials in our own solar system.

Astronomers recently found six stars that show periodic light changes due to planets passing in front of the star. By 2013 and the launch of Webb, hundreds of new systems will be found. Webb will be uniquely capable of studying these systems in detail to determine the sizes of the planets, and, in many cases, the compositions of their atmospheres.

Webb will also closely examine comets, which are made of the material left over from the formation of the planets. By allowing scientists to compare the make-up of comets with the material found in circumstellar disks and star formation regions, Webb will help us understand how planets form and evolve. In addition, comets are suspected of being the source of the Earth’s water, seeding the planet with water vapor through numerous impacts over billions of years. Webb will help confirm or dismiss this theory by examining comets’ composition.