Top exoplanet finds of 2013

LITTLE RUNT  Kepler-37b is the littlest planet found to date and looks puny compared to planets in our solar system and to those also orbiting parent star Kepler-37.

Ames/JPL-Caltech/NASA

With the addition this year of 180 new worlds to the Paris Observatory’s list of confirmed exoplanets, there are now more than 1,000 known planets orbiting stars other than the sun.

Here are some of the year’s most notable finds:

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1. The Earthiest

Kepler-78b is most similar to Earth in mass, diameter and composition; it could be made of rock with an iron core. But it’s no Earth analog, whizzing around its star in 8.5 hours, with temperatures exceeding 2,000° Celsius (SN Online: 10/30/13).

2. The wettest

HR 8799c’s atmosphere lacks methane, which could signal life, but does have water and carbon monoxide (SN: 4/6/13, p. 5). Water has also been found in the atmospheres of WASP-17b, HD209458b, WASP-12b, WASP-19b and XO-1b. 

3. The rogue

Planetary candidate PSO J318.5-22 has no parent star. The object is roughly six times the mass of Jupiter, has features similar to other directly imaged exoplanets, including HR 8799c, but floats through space all alone (SN Online: 10/9/13).

4. The runt

Kepler-37b is the littlest planet found to date. At 3,860 kilometers across, the exoplanet is about 30 percent of the diameter of Earth or 80 percent the width of Mercury (SN Online: 2/20/13).

1. The Earthiest Kepler-78b is most similar to Earth in mass, diameter and composition; it could be made of rock with an iron core. But it’s no Earth analog, whizzing around its star in 8.5 hours, with temperatures exceeding 2,000° Celsius. JASIEK KRZYSZTOFIAK/NATURE
1. The wettest HR 8799c’s atmosphere lacks methane, which could signal life, but does have water and carbon monoxide. Water has also been found in the atmospheres of WASP-17b, HD209458b, WASP-12b, WASP-19b and XO-1b. Ben Zuckerman/W. M. Keck Observatory
The rogue Planetary candidate PSO J318.5-22 has no parent star. The object is roughly six times the mass of Jupiter, has features similar to other directly imaged exoplanets, including HR 8799c, but floats through space all alone. V. CH. QUETZ/MPIA
The runt Kepler-37b is the littlest planet found to date. At 3,860 kilometers across, the exoplanet is about 30 percent of the diameter of Earth or 80 percent the width of Mercury. JPL-Caltech/Ames/NASA

Ashley Yeager is the associate news editor at Science News. She has worked at The Scientist, the Simons Foundation, Duke University and the W.M. Keck Observatory, and was the web producer for Science News from 2013 to 2015. She has a bachelor’s degree in journalism from the University of Tennessee, Knoxville, and a master’s degree in science writing from MIT.