Exoplanet Diversity: Atmosphere
Every planet has a unique atmosphere.Researchers have detected thousands of planets orbiting stars other than the Sun. The data show that these planets are even more varied than the planets and moons in our solar system. They range from small rocky planets a fraction of the size of Earth to large gas giants several times the size of Jupiter. Some orbit cool dwarf stars while others circle stars much hotter and more massive than the Sun. And like the objects in our solar system, they have a wide variety of compositions and structures.
Although no exoplanet is close enough to visit with a space probe, we can—under the right conditions—study an exoplanet’s atmosphere. When a planet passes in front of its star, some of the starlight is filtered through the planet’s atmosphere. We can analyze the pattern of the filtered light (a transmission spectrum) to figure out what the atmosphere is made of.
The transmission spectra shown here are models based on assumptions about the composition, temperature, and structure of the exoplanet’s atmosphere. In the future, scientists will compare actual data from observatories like the James Webb Space Telescope to the models to figure out which assumptions are correct and which are not.
Quick Facts: Atmosphere
Temperate Earth-sized exoplanet: TRAPPIST-1 e• Location: TRAPPIST-1 system, 40 light-years from Earth (inside the Milky Way)
• Diameter: 0.9 times the size of Earth's diameter
• Star: TRAPPIST-1, a very cool red dwarf
Warm Neptune-sized exoplanet: GJ 436 b
• Location : Gliese 436 system, 30 light-years from Earth (inside the Milky Way)
• Diameter: 4 times the size of Earth's diameter
• Star: Gliese 436, a cool red dwarf
Hot Jupiter exoplanet: WASP-62 b
• Location: WASP-62 system, 520 light-years away (inside the Milky Way)
• Diameter: 15 times the size of Earth's diameter
• Star: WASP-62, a hot blue-white star
Explore More About Exoplanet Diversity
Find out more with these additional resources from NASA’s Universe of Learning
Universe of Learning
Eyes on Exoplanets
Astroviz
Exoplanet Travel Bureau
Universe Unplugged
The Habitable Zone
Astropix
Illustrations of Exoplanets and Graphs of Exoplanet Data
Credits: Exoplanet Diversity
Artist’s conception of exoplanet Trappist-1e courtesy of NASA/JPL-Caltech
Artist’s conception of exoplanet GJ 436b courtesy of of NASA, ESA, and A. Feild and G. Bacon (STScI)
Artist’s conception of exoplanet WASP-62b courtesy of Kyoto University
Model transmission spectra of Hot Jupiter and Warm Neptune exoplanet from ExoCTK and the generic grid based on the ATMO grid published in Goyal, J., et al., 2018b, MNRAS
Model transmission spectrum of Temperate Earth-sized exoplanet courtesy of Tyler Robinson
Content development by Margaret W. Carruthers, Timothy Rhue II, Dr. Christopher Britt, and Dr. Brandon Lawton
Design by Elizabeth Wheatley, John Godfrey (STScI)
Web Development by Philippe Batigne (STScI)
Subject-matter expertise provided by Dr. Hannah Wakeford and Dr. Kevin Stevenson