This animation portrays an artist's concept of a distant hypothetical
solar system, about the same age as our own. It begins close to the star,
and then moves out past a number of planets. Though "extrasolar" planets
are too small to be seen with telescopes, astronomers have detected more
than 100 gas giants like Jupiter via their gravitational tug on their
parent stars.
The view pulls back to reveal the outer fringes of the system and a ring
of dusty debris that circles the star. This debris is all that remains of
the planet-forming disk from which the planets evolved.
Planets are formed when dusty material in a large disk surrounding a
young star clumps together. Leftover material is eventually blown out by
solar wind or pushed out by gravitational interactions with planets.
Billions of years later, only an outer disk of debris remains.
These outer debris disks are too faint to be imaged directly by
visible-light telescopes. They are washed out by the glare of the Sun.
However, NASA's Spitzer Space Telescope can detect their heat, or excess
thermal emission, in infrared light. This allows astronomers to study the
aftermath of planet building in distant solar systems like our own.
