New Horizons, Pluto, Earth 2.0, Kepler 452b

The planet takes 385 Earth days to orbit its star. It is 60% bigger than Earth, and lies within the conservative habitable zone of its parent star.

It has a probable mass five times that of Earth and its surface gravity is twice Earth's, though calculations of mass for exoplanets are only rough estimates. If it is a terrestrial planet, it is most likely a super-Earth with many active volcanoes due to its higher mass and density. The clouds on the planet would be thick and misty, covering much of the surface as viewed from space. From the surface, its star Kepler-452 would look almost identical to the Sun as viewed from the Earth.

It is not known if Kepler-452b is a rocky planet or a small gas planet, but based on its small radius, Kepler-452b has a reasonable chance of being rocky. It is not clear if Kepler-452b offers habitable environments. It orbits a G2V-type star, like the Sun, with nearly the same temperature and mass and 20% more luminous. However, the star is six billion years old, making it 1.5 billion years older than the Sun. At this point in its star's evolution, Kepler-452b is receiving 10% more energy from its parent star than Earth is currently receiving from the Sun. If Kepler-452b is a rocky planet, it may be subject to a runaway greenhouse effect similar to that seen on Venus.

1.      orbit(v) 環繞

2.      habitable(a) 可居住的，適於居住的

3.      exoplanet(n) (太陽系以外的)外部行星

4.      terrestrial(a) 陸地的；人間的；地球上的

5.      misty(a) 模糊的；多霧的；朦朧不清的

6.      luminous(a) 明亮的；清楚的；有見識的；明白易懂得

7.      Venus(n) 金星

1.      https://en.wikipedia.org/wiki/Kepler-452b