Astronomy college course/Pluto and planetary mass quiz/Original version of this quiz

Planetary mass quiz
{Which of the following is NOT used to measure the mass of a planet} + the rotation of the planet about its axis - the motion of an artificial satellite - the motion of a moon - the motion of a neighboring planet - all of these have been used {What is unusual about calculations of the mass of Pluto made in the early part of the 20th century?} - The estimates were correct to within less than 10% - The estimates were too low. Pluto was actually more massive than they thought. + The estimates were high. Pluto was less massive than they calculated - It was the first time a moon was used to calculate the mass of a planet - It was the first time a planet's period of orbit around the sun was used to calculate the planet's mass {Why was the discovery of Pluto peculiar?} - It was discovered during a survey looking for stars - It was seen by Galileo, who thought it was a star + It was discovered by a calculation based on flawed assumptions - It was seen by Halley, who was looking for comets - It was the first time a planet's period of orbit around the sun was used to calculate the planet's mass {Which of the following is NOT used to measure the mass of a planet} - the motion of an artificial satellite - the motion of a moon - the motion of a neighboring planet + all of these have been used {Which statement describes the relation between Pluto and Neptune} - Pluto's orbit lies outside Neptune's orbit - Pluto's orbit intersects Neptune's orbit an the two bodies will eventually collide - Pluto's orbit intersects Neptune's orbit but they avoid each other because Pluto's mass is too small + Pluto's orbit intersects Neptune's orbit but they don't collide because of an orbital resonance between the two