2.1. THE UNIVERSE

PRÁCTICA DE LABORATORIO Nº 2: Un cohete para explorar el universo.

- ORIGIN OF THE UNIVERSE

YouTube: National Geographic “Origins of the Universe 101”

YouTube: QuantumFracture “¿Dónde está la Tierra en el Universo?”

The most accepted theory of the origin of the Universe and its expansion is the Big Bang Theory:

1. EVERYTHING was concentrated in a little point that exploded 13,700,000,000 years ago.
2. The name of that explosion is Big Bang and it is called time zero.
3. At first, the temperature of the universe was very high.
4. Gradually it cooled down, which made it possible for stars and planets to form.

- COMPONENTS OF THE UNIVERSE

The Universe contains all matter, energy and space that exist.

• The Universe is made up of galaxies (galaxies are grouped in galaxy clusters).
• Galaxies are made up of stars.
• Some stars are alone. Others have planets orbiting them: planetary systems.
• Some planets have satellites.

Universe > Galaxies > Stars > Planetary systems

Definitions

• Galaxy: organization of thousands of millions of stars, interstellar dust and gases.
• Star: celestial body made of hydrogen (H) and helium (He) which emits their own light.
• Planet: body which orbits a star.
• Satellite: rocky body which orbits a planet.

How to express huge distances:

• Astronomical unit (AU): 150 million km (this is the distance from the Earth to the Sun).
• Lightyear (it is NOT a time unit): 9.5 trillion km.