There are no planets that cross the earth's orbit. Pluto (dwarf, or minor planet) and Neptune are the only planets whose orbits cross.
However there are over 100 asteroids (minor planets) that cross the earth's orbit.
Not a planet of any significant size, which would be easy to see, but it is possible that some pieces of rock are in a similar orbit to the Earth at the five Lagrangian Points of the Earth's orbit.
A planet in an orbit greater than any of the others.An object in orbit around a single planet is a moon or satellite of that planet.
No, Earth is a planet orbiting the Sun.
Pluto's orbit doesn't intersect with any planet's orbit. If it did, it's likely it would have collided with the planet billions of years ago.
No, a moon is a natuaral satellite and would always be in orbit around a planet. If it did'nt orbit the planet it would fall into the planet.
No planet has a perfectly circular orbit, though Venus has the least orbital eccentricity of any planet in our solar system.
Any of the objects outside of the Earths orbit.
The orbit of a planet is not any kind of physical object; it cannot "break". An orbit is the path that a satellite (natural or artificial) takes under the influence of gravity.
Yes there are millions of objects that orbit Saturn.
No
No, not all objects in space, including planets, orbit a star. Some planets are free-floating and do not orbit any star, while others orbit other celestial bodies like brown dwarfs or even black holes.
They're not 'on' any planet. They're in orbit around Jupiter.