Science Interest Group

Habitable Worlds Observatory

The Habitable Worlds Observatory SIG serves as a forum and focal point for the HWO community.

About HWO SIG

The Search for Earth-Like Planets in Habitable Zones

HWO is a large infrared/optical/ultraviolet space telescope recommended by the National Academies’ Pathways to Discovery in Astronomy and Astrophysics for the 2020s.

"Inspired by the vision of searching for signatures of life on planets outside of our solar system, and by the transformative capability such a telescope would have for a wide range of astrophysics, the priority recommendation in the frontier category for space is a large (~6 m diameter) IR/O/UV telescope with high-contrast (10^-10) imaging and spectroscopy. This is an ambitious mission, of a scale comparable to the HST and JWST space telescopes. It is also one that will be revolutionary, and that worldwide only NASA is positioned to lead." (Text source: Decadal Survey on Astronomy and Astrophysics 2020 [Astro2020])

Habitable Worlds Observatory

An earthlike planet with oceans and clouds is seen in space, with its host star in the background.

This artist’s concept depicts Kepler-186f, the first validated Earth-size planet to orbit a distant star in the habitable zone — a range of distance from a star where liquid water might pool on the planet’s surface. The discovery of Kepler-186f confirms that Earth-size planets exist in the habitable zones of other stars and signals a significant step closer to finding a world similar to Earth.The size of Kepler-186f is known to be less than ten percent larger than Earth, but its mass, composition and density are not known. Previous research suggests that a planet the size of Kepler-186f is likely to be rocky. Prior to this discovery, the “record holder” for the most “Earth-like” planet went to Kepler-62f, which is 40 percent larger than the size of Earth and orbits in its star’s habitable zone.Kepler-186f orbits its star once every 130 days and receives one-third the energy that Earth does from the sun, placing it near the outer edge of the habitable zone. If you could stand on the surface of Kepler-186f, the brightness of its star at high noon would appear as bright as our sun is about an hour before sunset on Earth.Kepler-186f resides in the Kepler-186 system about 500 light-years from Earth in the constellation Cygnus. The system is also home to four inner planets, seen lined up in orbit around a host star that is half the size and mass of the sun.The artistic concept of Kepler-186f is the result of scientists and artists collaborating to imagine the appearance of these distant worlds.

NASA/Ames/SETI Institute/JPL-Caltech

Ultraviolet Astrophysics

Ultraviolet wavelengths are important to answer many questions in astrophysics. In addition to being sensitive to optical and near-infrared, Habitable Worlds Observatory will be sensitive to ultraviolet light.