Astronomy
- Created by: Lucy S
- Created on: 05-04-13 13:20
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- Astronomy
- The Solar System
- Some planets have moons, which orbit their planets.
- The solar system consists of planets orbiting the Sun.
- Planets & moons are visible because they reflect light from the Sun.
- The Sun is a star, producing vast amounts of energy.
- Dwarf planets, asteroids & comets also orbit the Sun.
- Comets
- Comets orbit the Sun.
- They have a body of dust & ice.
- They have a highly elongated orbit.
- Their paths come close to the Sun for part of the path & then travel a long way away from the Sun.
- They have a 'tail' of melting ice & debris pointing away from the Sun.
- They are most visible & travel quickest when close to the Sun.
- Galaxies
- The universe is a large collection of billions of galaxies.
- A galaxy is a large collection of billions of stars.
- Our galaxy is called the Milky Way.
- Gravitational Forces
- Gravity keeps the moons in orbit of their planets.
- Gravity keeps the planets in orbit around the Sun.
- Planets orbit the Sun in ellipses.
- Gravity keeps the Solar System in orbit around the centre of the Milky Way.
- The Strength of Gravity
- Gravity is the force that attracts objects with mass to each other.
- The strength of gravity is measured with Gravitational field strength (g).
- Gravitational field strength varies from planet to planet, moon to moon.
- On Earth, g=10N/kg.
- Orbital Speed
- V = 2(pi)r / T
- Orbital speed = 2 x (pi) x orbital radius / time period.
- V = 2(pi)r / T
- Planets move more quickly when they are closer to the Sun.
- The Solar System
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