space

• a moon is a natural satellite that orbits a planet
• a planet is a large ball of matter made round by gravity, orbiting a star
• lightyear is the distance light travels in a year
• big bang theory is how the universe formed from a singularity: an infinitly dense hot point into its present state
• satelites are used for gps, forcasting, communications, spying
• geostationary sattelites orbit at 36000km and have a period of 24 hours
• challenges of space travel are maneovering an aircraft in a zero friction atmosphere, maintaining sufficiant energy to operate life support, fuel on take off, radiation exposure and re-entry( extreme temps where the aircraft is an unpowered glider)