Because Earth is not the only planet in the solar system. The gravity of the others would gradually affect such a planet, bringing it into view in no more than about 30 years. Also, it would have gravity of its own, and would have been discovered by the pull it exerted on the rest of the solar system, including Earth!
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.
It is the only large moon in the Solar System with a retrograde orbit, which is an orbit in the opposite direction to its planet's rotation.
You are thinking of Pluto. Pluto is now designated a minor planet.
A planet with an eccentric orbit that crosses the orbit of another planet would create gravitational interactions and potential collisions between the two planets. This scenario could lead to disturbances in their orbits, potentially causing erratic behavior and possible impacts between the planets.
The orbits of Pluto and Neptune cross, so sometimes Pluto is inside Neptune's orbit.
Venus
Neptune is the outermost planet, and is farthest from 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.
No. A planet's mass does not determine the position of its orbit.
The counterclockwise spin of a planet or moon is called retrograde rotation. This means the object is rotating in the opposite direction of its orbit around another body, like a planet rotating against the direction of its orbit around the sun.
its orbit crosses with another plant
We call that path the "orbit" of the orbiting body. Note: You would not ever see a planet orbiting another planet. At least, if you did, you would not call them both planets.
Earths Orbit? Earths Orbit?
A moon is an object that orbits a planet. A planet cannot orbit another planet.
It is the only large moon in the Solar System with a retrograde orbit, which is an orbit in the opposite direction to its planet's rotation.
You are thinking of Pluto. Pluto is now designated a minor planet.
An orbit is the path of a planet, star, or satellite through space around another object. The path the orbit is simply the orbit.