Space Flight to the Stars

Celestial Objects• “Celestial” means sky• Objects we can see in the sky

such as the Sun, Moon, Earth and other planets are all examples of celestial objects

Solar System• The Sun together with all the planets and other

celestial objects that are held by the Sun’s gravitational attraction and orbit around it.

Inner Solar System• The planets in order from the Sun are:• Mercury, Venus, Earth, Mars, Jupiter, Saturn,

Uranus, Neptune, (Pluto)• You can easily remember the order using this

mnemonic device:“My Very Educated Mother Just Served Us Nine Pizzas”• Planets of the Inner Solar System include:

Mercury, Venus, Earth and Mars

Outer Solar System• The planets that make up the Outer Solar System

are:

• Jupiter, Saturn, Uranus, Neptune

Other Celestial Objects• Star – a hot ball of plasma; the Sun is a star in

which nuclear fusion reactions occur to produce enormous amounts of energy

• Asteroid Belt – past Mars there is a region of rocky debris that forms a ring around the Sun

• Moons• Comets• Minor Planets - Pluto

Measurements in Space• Astronomical Units – measures distances in

space. 1 AU = average distance between the Sun and Earth (about 150 million km)

• Light-year (ly) – the distance that a beam of light can travel through space in 1 year. It is about 63 000 AU or 9000 billion km.o At the speed of light you can travel around the Earth 7 times in 1

second!

Stars• Supernova – occurs when a star explodes• Nebula – large cloud of dust and gas; “star

nurseries”, because stars develop from their dust and gas