Gliese 581g

• Gliese 581d is the third planet from its host star in the Gliese 581 system, or the fifth planet if you include two unconfirmed planets.
• Gliese 581g is an unconfirmed exoplanet in the Gliese 581 system.
• There are four confirmed and one other unconfirmed planet in the system.
• The planet is the fourth in order from its red dwarf host star.
• Gliese 581g has a mass of around 3 to 4 times that of Earth, its radius is thought to be around 1.5 times larger.
• The mass indicates that it is probable Gliese 581g is a rocky planet with sufficient gravity to hold onto its atmosphere.
• Gliese 581g is one of the most Earth like planets detected in the habitable zone of its star.
• It is believed that Gliese 581g is tidally locked meaning that the same side of the planet is always facing its host star.
• It is thought that the force of gravity on Gliese 581g is very similar to that on Earth.
• Gliese 581g receives similar levels of sunlight from its host star as Earth does from the Sun.

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Gliese 581g revolves around its host star at a distance of 13.6 million miles (22 million km) and takes 37 days to make one complete orbit. The atmospheric composition is unknown but theoretical models suggest that if the planet has high enough levels of carbon dioxide in its atmosphere then it's possible that Gliese 581g could possess a tropical climate. Despite the controversy surrounding the confirmation of Gliese 581g it is still considered as one the most promising candidates for potential habitability outside our solar system.

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Host Star: Gliese 581
Host Star Type: Red Dwarf - M Class
Host Star Mass: 31% of Sun
Constellation: Libra
Distance from Earth: 20.3 light years
Planets Detected in System: 4 confirmed, 2 unconfirmed
Discovery Date: September 2010
Detection Method: Radial Velocity
Exoplanet Type: Super Earth

Mass: Around 3.5 x Earth
Diameter: Around 130% to 200% greater than Earth depending on composition
Distance from host star: 13.6 million miles (22 million km)
Orbital Period: 37 days
Atmosphere: Unknown, models suggest an atmosphere composed of one fifth carbon dioxide would provide the most habitable environment.
Temperature: Unknown, potential temperatures vary dramatically depending on atmospheric conditions.
Gravity: Around 10% to 70% stronger than Earth's gravity.
Possibility of Life: Depending on atmospheric and surface conditions it is possible life could exist on Gliese 581g.

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