# The TRAPPIST-1 Exoplanetary System

TRAPPIST-1 is a star with 0.08 times the mass of the Sun, and 0.12 times its radius. It is located 40.54 light years away from the solar system.

TRAPPIST-1 is known to have 7 exoplanets in orbit around it.

## TRAPPIST-1 b

TRAPPIST-1 b was discovered by the La Silla Observatory observatory using the transit method. Its discovery was announced in 2016-05. Its semi-major axis is 0.01 astronomical units, as compared to Earth's which is 1 astronomical unit. It takes 1.51 Earth days to complete an orbit around its host star, TRAPPIST-1.

Its eccentricity, the extent to which the shape of the exoplanet's orbit departs from a perfect circle (Earth's is 0.0167, which is why the shape of Earth's orbit is circular rather than oval in appearance), is 0.081, which means that when TRAPPIST-1 b is at is at its closest point to its host star, 0.01 astronomical units separates the two, and when it is at its farthest point, this number is 0.01. In the case of Earth, these numbers are 0.9832899 and 1.0167103 respectively.

The mass of TRAPPIST-1 b is 0.85 times the mass of Earth. The radius of TRAPPIST-1 b is 1.086 that of Earth. At less than 1.5 Earth masses, TRAPPIST-1 b is a regular terrestrial planet, much like the terrestrial planets we find in our solar system, namely Mercury, Venus, Earth and Mars.

## TRAPPIST-1 c

TRAPPIST-1 c was discovered by the La Silla Observatory observatory using the transit method. Its discovery was announced in 2016-05. Its semi-major axis is 0.02 astronomical units, as compared to Earth's which is 1 astronomical unit. It takes 2.42 Earth days to complete an orbit around its host star, TRAPPIST-1.

Its eccentricity, the extent to which the shape of the exoplanet's orbit departs from a perfect circle (Earth's is 0.0167, which is why the shape of Earth's orbit is circular rather than oval in appearance), is 0.083, which means that when TRAPPIST-1 c is at is at its closest point to its host star, 0.01 astronomical units separates the two, and when it is at its farthest point, this number is 0.02. In the case of Earth, these numbers are 0.9832899 and 1.0167103 respectively.

The mass of TRAPPIST-1 c is 1.38 times the mass of Earth. The radius of TRAPPIST-1 c is 1.056 that of Earth. At less than 1.5 Earth masses, TRAPPIST-1 c is a regular terrestrial planet, much like the terrestrial planets we find in our solar system, namely Mercury, Venus, Earth and Mars.

## TRAPPIST-1 d

TRAPPIST-1 d was discovered by the La Silla Observatory observatory using the transit method. Its discovery was announced in 2016-05. Its semi-major axis is 0.02 astronomical units, as compared to Earth's which is 1 astronomical unit. It takes 4.05 Earth days to complete an orbit around its host star, TRAPPIST-1.

Its eccentricity, the extent to which the shape of the exoplanet's orbit departs from a perfect circle (Earth's is 0.0167, which is why the shape of Earth's orbit is circular rather than oval in appearance), is 0.07, which means that when TRAPPIST-1 d is at is at its closest point to its host star, 0.02 astronomical units separates the two, and when it is at its farthest point, this number is 0.02. In the case of Earth, these numbers are 0.9832899 and 1.0167103 respectively.

The mass of TRAPPIST-1 d is 0.41 times the mass of Earth. The radius of TRAPPIST-1 d is 0.772 that of Earth. At less than 1.5 Earth masses, TRAPPIST-1 d is a regular terrestrial planet, much like the terrestrial planets we find in our solar system, namely Mercury, Venus, Earth and Mars.

## TRAPPIST-1 e

TRAPPIST-1 e was discovered by the Multiple Observatories observatory using the transit method. Its semi-major axis is 0.03 astronomical units, as compared to Earth's which is 1 astronomical unit. It takes 6.10 Earth days to complete an orbit around its host star, TRAPPIST-1.

Its eccentricity, the extent to which the shape of the exoplanet's orbit departs from a perfect circle (Earth's is 0.0167, which is why the shape of Earth's orbit is circular rather than oval in appearance), is 0.085, which means that when TRAPPIST-1 e is at is at its closest point to its host star, 0.03 astronomical units separates the two, and when it is at its farthest point, this number is 0.03. In the case of Earth, these numbers are 0.9832899 and 1.0167103 respectively.

The mass of TRAPPIST-1 e is 0.62 times the mass of Earth. The radius of TRAPPIST-1 e is 0.918 that of Earth. At less than 1.5 Earth masses, TRAPPIST-1 e is a regular terrestrial planet, much like the terrestrial planets we find in our solar system, namely Mercury, Venus, Earth and Mars.

With a semi-major axis of 0.02817 astronomical units, and a mass of 0.62 Earth masses, TRAPPIST-1 e could, potentially, be a habitable planet with stable bodies of liquid water on its surface, like Earth.

## TRAPPIST-1 f

TRAPPIST-1 f was discovered by the Multiple Observatories observatory using the transit method. Its semi-major axis is 0.04 astronomical units, as compared to Earth's which is 1 astronomical unit. It takes 9.21 Earth days to complete an orbit around its host star, TRAPPIST-1.

Its eccentricity, the extent to which the shape of the exoplanet's orbit departs from a perfect circle (Earth's is 0.0167, which is why the shape of Earth's orbit is circular rather than oval in appearance), is 0.063, which means that when TRAPPIST-1 f is at is at its closest point to its host star, 0.03 astronomical units separates the two, and when it is at its farthest point, this number is 0.04. In the case of Earth, these numbers are 0.9832899 and 1.0167103 respectively.

The mass of TRAPPIST-1 f is 0.68 times the mass of Earth. The radius of TRAPPIST-1 f is 1.045 that of Earth. At less than 1.5 Earth masses, TRAPPIST-1 f is a regular terrestrial planet, much like the terrestrial planets we find in our solar system, namely Mercury, Venus, Earth and Mars.

With a semi-major axis of 0.0371 astronomical units, and a mass of 0.68 Earth masses, TRAPPIST-1 f could, potentially, be a habitable planet with stable bodies of liquid water on its surface, like Earth.

## TRAPPIST-1 g

TRAPPIST-1 g was discovered by the Multiple Observatories observatory using the transit method. Its semi-major axis is 0.05 astronomical units, as compared to Earth's which is 1 astronomical unit. It takes 12.35 Earth days to complete an orbit around its host star, TRAPPIST-1.

Its eccentricity, the extent to which the shape of the exoplanet's orbit departs from a perfect circle (Earth's is 0.0167, which is why the shape of Earth's orbit is circular rather than oval in appearance), is 0.061, which means that when TRAPPIST-1 g is at is at its closest point to its host star, 0.04 astronomical units separates the two, and when it is at its farthest point, this number is 0.05. In the case of Earth, these numbers are 0.9832899 and 1.0167103 respectively.

The mass of TRAPPIST-1 g is 1.34 times the mass of Earth. The radius of TRAPPIST-1 g is 1.127 that of Earth. At less than 1.5 Earth masses, TRAPPIST-1 g is a regular terrestrial planet, much like the terrestrial planets we find in our solar system, namely Mercury, Venus, Earth and Mars.

With a semi-major axis of 0.0451 astronomical units, and a mass of 1.34 Earth masses, TRAPPIST-1 g could, potentially, be a habitable planet with stable bodies of liquid water on its surface, like Earth.