An artistic rendition of a nomad object
wandering the interstellar medium. The
object is intentionally blurry to represent
uncertainty about whether or not it has an
atmosphere. A nomadic object may be an
icy body akin to an object found in the
outer Solar System, a more rocky material
akin to asteroid, or even a gas giant similar
in composition to the most massive Solar
System planets and exoplanets. (Image by Greg Stewart/SLAC)

Planets simply adrift in space may not only be common in the cosmos; in the Milky Way Galaxy alone, their number may be in the quadrillions. Three experts discussed what this might mean, whether a nomad planet could drift close to our solar system, and how it is possible for a nomad planet to sustain life. 

See this roundtable discussion at the Kavli Foundation that features Harvard Professor Dimitar D. Sasselov and others. 

Spotlight Live: Nomads of the Galaxy