Astronomy Flashcards
What is a solar system?
A star and everything that is gravitationally bound to it.
What is an orbit?
A circular motion around an object due to gravity.
What is a planet?
A spherical object that orbits a star (whilst clearing its orbit)
What is a satellite?
Anything that orbits a planet.
What is a moon?
A natural satellite.
What force causes orbits?
Gravity
Give some similarities between the orbits of planets and satellites.
Both are circular (or elliptical).
Both are due to gravity.
Give some differences between the orbits of planets and satellites.
Planets orbit a star, satellites orbit a planet.
Planets orbits tend to have larger radiuses that satellites.
What is a galaxy?
A collection of billions of stars.
What is the name of our galaxy?
The Milky Way
What is the order of the planets?
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
Name some objects in the solar system that AREN’T planets.
Pluto (and other dwarf planets, like Ceres and Eris). Asteroids (in the asteroid belt) Comets Moons (Centaurs)
Explain how, for an orbit, the VELOCITY of the object changes but the SPEED doesn’t.
The force of GRAVITY is PERPENDICULAR to the direction the object is travelling, so the velocity only changes DIRECTION, without changing the MAGNITUDE.
Explain why an orbit’s speed must change when it changes radius.
The closer the object gets to the object its orbiting, the larger the force of GRAVITY is. Therefore, the faster it has to travel in order to move in a circle.
