Final answer:
The distance of space junk orbiting Earth varies due to gravitational forces, influenced by the interaction between masses and gravity, making the claim that it is constant over time or depends on Earth's magnetic field incorrect. Orbits can have different shapes, including nearly circular or highly eccentric, affected by gravity.
Step-by-step explanation:
When considering the distance of space junk orbiting the Earth, the most accurate claim is that the debris's distance varies due to gravitational forces. The path that orbiting objects take around a primary body such as Earth is shaped by the interactions of gravitational forces, resulting in orbits that can have points of closest approach and furthest distance—the perigee and apogee, respectively. Unlike mass, which is constant, weight can vary depending on the force of gravity. The force of gravity also causes the orbits to be nearly circular and in the same plane, as seen with the planets orbiting the Sun. The third law of Kepler, when combined with Newton's law of gravitation, illustrates the importance of mass by stating a³ = (M₁ + M₂) × P², which describes how the period of an orbit relates to the mass of the objects and their distance from each other. However, this is affected by many factors, and calculating the precise gravitational interaction of more than two bodies requires complex computation, especially when dealing with objects such as satellites and space debris.