When Astronomy magazine compiled its list of the “Top 10 exoplanets,” we had no problem filling all the spots. In fact, it proved more difficult winnowing out the many worthy contenders. With the tally of known exoplanets now approaching 1,000, the number of exotic beasts in the exoplanet zoo easily surpasses 100.
We culled five more oddballs from the exoplanet menagerie to extend the list. You’ll meet HD 80606 b, which reaches a breakneck speed of 529,000 mph (851,000 km/h) when it swings closest to its parent star; WASP-17b, which has a density one-tenth that of water and would float in an ocean if you could find one big enough; and three other standouts. These five remarkable worlds certainly deserve a spot in any listing of fascinating, exciting, and intriguing exoplanets.
NASA/ESA/ D. Aguilar (Harvard-Smithsonian CfA)
GJ 1214 b
Discovery year: 2009
Mass (Earths): 0.15
Orbital radius (AU): 0.014
Coolness factor: Water world enshrouded by a thick, steamy atmosphere
WASP-17b
Discovery year: 2009
Mass (Earths): 156
Orbital radius (AU): 0.0515
Coolness factor: Lowest-density planet (0.1 g/cc); some 70 times less dense than Earth
Kepler-37b
Discovery year: 2013
Mass (Earths): (unknown)
Orbital radius (AU): 0.1003
Coolness factor: Smallest-diameter exoplanet (non-pulsar variety) at 0.30 Earth radii
NASA/ESA/A. Schaller (for STScI)
SWEEPS-11
Discovery year: 2006
Mass (Earths): 3,000
Orbital radius (AU): 0.03
Coolness factor: Most distant confirmed planet from Earth (27,700 light-years away)
NASA/JPL-Caltech/G. Laughlin, et al.
HD 80606b
Discovery year: 2001
Mass (Earths): 1,250
Orbital radius (AU): 0.449
Coolness factor: Fastest-moving planet (529,000 mph [851,000 km/h] at closest point to its star)
