Earth is.
Natural objects that orbit a star form that star's solar system. The name comes from the name of our star, which is Sol. Earth is part of the Solar System. Another star's system might be referred to by the name of that star, as in the Polaris System.
It is called a "planetary system" or "solar system" (the latter term is used alone or capitalized to mean the Sun's system of planets, moons, asteroids, meteoroids, and comets).
Our Sun, although with the amount of debris in Earth orbit...
"solar system" is the term used to describe planets orbiting a star. We know that planets also orbit binary and tertiary star systems, these would be different kinds of solar systems.
A solar system.
Earth is.
Earth is.
The Galilean moons orbit Jupiter.
169 moons.
There are 180 moons in our solar system.
A solar system
I assume you mean "the focus of the ellipse". That's the Earth, since the Moon revolves around Earth.
the orbit of planets around the Sun in the Solar systemthe orbit of moons around their planets in the Solar system
the orbit of planets around the Sun in the Solar systemthe orbit of moons around their planets in the Solar system
All object except the Sun orbit round the Sun. The moons also orbit round their planets.
In most cases, the moons are about as old as the planets they orbit, perhaps slightly younger. Most objects in the solar system formed when the solar system did.
No satellites are known to orbit Mercury or Venus.