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What else can I help you with?
Why does Pluto not anymore considered as planet?
The definition of a planet was changed and it does not meet that definition.
Is Pluto a planet in 2015?
The International Astronomical Union "demoted" Pluto from true planet to dwarf or minor planet status in 2006; it is highly unlikely to reverse that decision and change the definition back to include Pluto as a planet in 2015.
Does europa match the definition of a planet although it is a moon?
No. Europa does not meet the definition of a planet because it does not orbit the sun. It orbits the planet Jupiter.
What does mercury revolve around?
Mercury is a planet. By definition, it revolves around the sun.
What is the definition of 'Earth'?
a round planet with living things on it.
What planet some astronomers don't think is a planet?
Astronomers have decided that Pluto does not meet the definition of a planet.
What is the definition of a Moon?
A moon orbits a planet.
What is the definition of a planet and how many planets are there?
8
What planet is only one AU from the sun?
By definition, it's the Earth.
How many solar system planet?
8 that meet the current official definition of planet.
What exactly makes a planet a planet?
The definition is not always very clear. For our Solar System, the definition is used that a planet orbits the Sun, and has "cleared its neighborhood", meaning that there are no other orbits of comparable size crossing its orbit. Note that this definition makes no direct reference to the planet's size! There is not yet a clear definition for other solar systems; this will need to be clarified, once we start discovering smaller and smaller objects.
What is the definition of exosphere?
The outermost region of a planet's atmosphere
