Unit 1-The Earth In The Universe Flashcards
The geocentric model
This theory said that the Earth was the centre of the universe and the Sun, the Stars and the Moon orbited it
The heliocentric model
Copernicus proposed that the Sun was the centre of the universe.
The solar system (characteristics)
Bodies that orbit the Sun, more than 99% of all the mass in the solar system is made up by the Sun, rest- celestial bodies that orbited it, 8 planets, at least 5 dwarf planets, millions of asteroids and comets, more than 100 satellites
Requirements for a celestial body to be considerated as a planet
It orbits the Sun, it has swept up the asteroids and comets from the area around its orbit, it has a mass large enough to adopt an almost spherical shape.
Which bodies can we find around around the Sun? Can you name them?
Satellites, asteroids, comets, dwarf planets and planets.
Could you tell me which are called inner planets and which are called inner planets? Why?
The inner planets are Mercury, Venus, Earth and Mars. The outer planets are Jupiter, Saturn, Uranus and Neptune. Because they are divided by an asteroid belt.
Has the Earth been always considerated as a sphere? Explain your answer
Around Erasthotene´s time ( 3rd century BC) most people believed that the Earth was flat.
Why the Earth is an imperfect sphere?
The Earth is spherical, but it is not a perfect sphere. In the direction of it´s axis of rotation, i.e. from the North Pole to the South Pole, the Earth´s diameter is 12,714. At the Equator the diameter is 12,756.
Which two type of movement has the Earth performed? Explain them.
Rotation:The Earth spins on an imaginary axis, that passes through its centre, from the North Pole to the South Pole. It takes 24 hours or one day.
Revolution: The Earth revolves around the Sun and describes an orbit, that takes 365 days or one year.
The distance between the Earth and the Sun varies slighty throughout the year, why? Name and explain the closest and the furthest point.
The Earth follows an elliptical orbit around the sung, meaning that its distance varies slighty throughout the year.
Aphelion: Is the closest point to sun, its around July 4th.
Perihelion: Is the furthest point to Sun, its around January 4th.
Why does our planet have day and night?
Because Earth´s axis of rotation was perpendicular to the ecliptic plane, day and night would both last 12 hours everywhere, all year long.
Why are the seasons?
The Earth´s seasons are a result of Earth´s titled axis, which means that one hemisphere faces the sun during part of the orbit (summer). During this time, the Sun´s rays hit that hemisphere at a more direct angle, and it recieves more heat.
