Asked in Planetary Science, Planet Mercury
What is in the planet mercurys atmosphere made of?
Mercury has a surface pressure that is near enough zero (or a vacuum), the planet holds no real atmosphere due to its small size. There are some trace gases at the surface, but not what one would call a proper atmosphere. ...
Why is Pluto considered a dwarf planet and Mercurys not Mercury's smaller than Pluto?
The definition of planet includes more than just size. It also includes that the planet's gravitational field, besides existing, has cleared its orbit. (of debris, planetesimals, etc.) Pluto has not done this, while Mercury has. ...