|MadSci Network: Astronomy|
A probe that is sent to Earth orbit cannot exceed the speed of 25,000 miles per hour. Probes that are sent to explore other bodies of the Solar System must exceed this speed initially although their speed decreases later on the trip. Typically a probe that is sent to an orbit near the Earth's orbit will have a speed around 70,000 miles per hour. Comets have very different speeds, and their speed increases as they approach the Sun. Those with orbits near the Earth have also speeds around 70,000 miles per hour. Comets with very elongated orbits can have speeds up to 500,000 miles per hour at the closest point of their orbit to the Sun. These comets can take millions of years to return to the Sun vicinity. At their farthest point in orbit their speeds is minimum and can be only a few thousand miles per hour. Vladimir Escalante Ramirez
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