Question

part d
kepler - 186f is much closer to its sun than earth is to its sun. why is it considered to be in the habitable zone even though its so close to a sun?

Explanation:

The habitable zone depends on the star's luminosity. Kepler - 186f's sun is a red dwarf, which is less luminous than our Sun. So, even though Kepler - 186f is closer to its star, it still receives a similar amount of energy as Earth does from our Sun, allowing for liquid water (a key for habitability) to potentially exist on its surface.

Answer:

Kepler - 186f's sun is less luminous (a red dwarf), so the planet receives appropriate energy for potential liquid water (habitable) despite being close.