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Kepler-78b

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description Kepler-78b Overview

Kepler-78b is an Earth-sized rocky exoplanet announced in 2013, notable for being the first exoplanet confirmed to possess an Earth-like density and an iron-rock composition. It was discovered using data from NASA's Kepler space telescope and orbits a K-type star. The planet completes an orbit around its host star in approximately 8.5 hours, classifying it as an ultrashort-period planet. This incredibly close orbit makes its surface extremely hot, entirely inhospitable to life as we know it.

help Kepler-78b FAQ

How long is a year on Kepler-78b?

Kepler-78b completes an orbit in about 8.5 hours, so its year is shorter than a normal working day on Earth. It circles its star at an extremely small distance and is far too hot to be Earth-like in habitability.

Why was Kepler-78b important to exoplanet science?

In 2013, separate teams measured a mass and density consistent with a body made mainly of rock and iron. It became the first Earth-sized exoplanet whose rocky composition was established through both radius and mass measurements.

Is Kepler-78b actually similar to Earth?

Its size and bulk composition are broadly Earth-like, with a measured density comparable to Earth's. Its environment is radically different because the planet orbits in only 8.5 hours and has a surface hot enough to melt rock.

How did astronomers detect and weigh Kepler-78b?

NASA's Kepler spacecraft detected the small dip in starlight when the planet transited its host star. Ground-based spectrographs then measured the star's tiny radial-velocity wobble, allowing researchers to estimate the planet's mass.

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