The period is a time. The time in which a pattern (full orbit) repeats. You can thus measure it in seconds, minutes, hours, etc. It's just the definition, no proof.
You can calculate this with Kepler's Third Law. "The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit." This is valid for other orbiting objects; in this case you can replace "planet" with "satellite". Just assume, for simplicity, that the satellite orbits Earth in a circular orbit - in this case, the "semi-major axis" is equal to the distance from Earth's center. For your calculations, remember also that if the radius is doubled, the total distance the satellite travels is also doubled.
Assuming the satellite moves around Earth, the only relevant force is Earth's gravitation.
it is when earth stops orbiting
Most velocities are measured relative to Earth.Most velocities are measured relative to Earth.Most velocities are measured relative to Earth.Most velocities are measured relative to Earth.
parallel to the surface of the Earth
The largest satellite orbiting the Earth is the Moon.
The only natural satellite orbiting Earth is the moon.
Photos taken of Earth from an orbiting satellite
I saw a satellite orbiting around earth.
It is the moon.
It is the moon.
You can use Kepler's Third Law to calculate this.
By orbiting the earth about once a month.
Yes. The earth has many man-made satellites orbiting the earth, but there's also one natural satellite. This satellite is the moon, orbiting earth at about 2288 miles per hour (3683 kilometers per hour)
A satellite is not always a robotic module constructed on Earth and launched into orbit. A satellite, in fact, is any object which is orbiting another. The orbiting object is the satellite of whatever it orbits. By now you ought to be able to guess it, but if not, it is the moon.
At periapsis, that is, when it is closest to Earth in its orbit.
Sputnik-I