A recent study published in the Astrophysical Journal Letters investigates the potential existence of Mars-sized free-floating planets (FFPs)—also known as rogue planets, starless planets, and wandering planets—that could have been captured by our sun's gravity long ago and orbit in the outer solar system approximately 1,400 astronomical units (AU) from the sun. For context, the farthest known planetary body in the solar system is Pluto, which orbits approximately 39 AU from the sun, and is also part of the Kuiper Belt, which scientists estimate extends as far out as 1,000 AU from the sun.

A recent study published in the Astrophysical Journal Letters investigates the potential existence of Mars-sized free-floating planets (FFPs)—also known as rogue planets, starless planets, and wandering planets—that could have been captured by our sun’s gravity long ago and orbit in the outer solar system approximately 1,400 astronomical units (AU) from the sun. For context, the farthest known planetary body in the solar system is Pluto, which orbits approximately 39 AU from the sun, and is also part of the Kuiper Belt, which scientists estimate extends as far out as 1,000 AU from the sun.