WASHINGTON-A NASA satellite has discovered an Earth-sized world within its star’s “habitable” area -- where liquid water could possibly exist. The world is known as an exoplanet. This term is used for planets that orbit a star outside of our own solar system.

NASA’s Transiting Exoplanet Survey Satellite, or TESS, made the discovery. TESS was launched in 2018 to expand on the work of earlier exoplanets that space telescopes had discovered. Exoplanets are hard for telescopes to identify; the bright lights of the stars they orbit can hide them.

TESS contains four individual cameras that search for drops in light levels. This may be linked to planetary movements. Scientists then attempt to confirm the presence of worlds and try to estimate the size and orbit of the planets.

The newly found planet, called “TOI 700 d,” is about 100 light years away from Earth, NASA’s Jet Propulsion Laboratory said. It is about 20 percent larger than Earth. TOI 700 d is one of three planets orbiting a star known as TOI 700. The discovery was announced during a recent meeting of the American Astronomical Society in Honolulu, Hawaii.

Astronomers have not yet been able to measure TOI 700 d’s mass. Such measurements will be necessary to estimate whether it is a rocky planet like Earth, or a gassy one like Neptune.

Elisa Quintana is an astronomer at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. She told Nature magazine that few Earth-sized planets have been discovered in habitable areas. She says this makes the latest find “exciting.” Scientists say they confirmed the planet information using NASA’s Spitzer Space Telescope. They have modeled the planet’s possible environments to help support future observation activities.

The modeling team for TOI 700 d is led by Gabrielle Engelmann-Suissa. She is a visiting research assistant at Goddard. She said in a statement that the modeling process is very important to help learn more about conditions on TOI 700 d as more data is collected.

“It’s exciting because no matter what we find out about the planet, it’s going to look completely different from what we have here on Earth,” Engelmann-Suissa said.