Solar System (Origin of the Universe)

• asteroid - pieces of rocks in space
• big bang theory - the universe began as a very hot, dense ball of energy, which expanded and cooled
• solar nebula - clouds of gas and dust from which the solar system formed
• planet - a large body that orbits the sun and is not a satellite of another planet
• galaxy - a large collection of stars, planets , and gas held together by gravity, and often containing a black hole at its centre
• milky way - the galaxy that our solar system is in
• star - a large, hot, luminous body that emits light and heat
• sun - the star that gives us light and heat, and is the source of all life on earth
• moon - smaller object orbiting a planet
• planetisimal - tiny grains and the larger planetary objects that formed in the solar nebula
• solar system - the sun and the collection of stars, planets, and other objects that orbit the sun
• light year - the distance light travels in a year (5.9 trillion years)
• gravity - a force that pulls the earth towards the sun and keeps the planets in orbit
• meteor - a debris in space that enters the earth's atmosphere and burns up
• moon's gravity - it is 1/6 of the Earth's gravity
• atmosphere - the layer of gases surrounding the earth that protects it from the sun's heat
• shooting star - a meteor that burns up in the atmosphere, leaving a bright trail of light
• comet - it is compared to dirty snowballs; it has a particular path and trail; made up of ice (frozen gases mostly) and rocks
• sirius - the brightest star in the night sky
• asteroid belt - a region of space between Mars and Jupiter where asteroids orbit the sun
• geocentric - the earth is the center of the universe and everything revolves around it
• heliocentric - model of the universe in which the earth orbits the sun, not the other way around
• the closer you are to the sun, the shorter the time to revolve
• meteoroid - located at the outer space of the solar system, and is a small rock or piece of rock that is moving through space
• meteorites - rocks that originated in space and are found on Earth.
• baryonic matter - "ordinary" matter, made of protons and neutrons that comprises atoms, planets, stars, galaxies, and other bodies
• dark matter - has gravity but does not emit light
• dark energy - source of anti-gravity; a force that counteracts
• 13.8B - how old is the universe
• steady state theory - the universe is eternal and has always existed; it is expanding but maintaning a constant average density
• Mercury - nearest to the sun
• Venus - hottest planet
• Earth - blue planet; only planet known to support life
• Mars - red planet; closest planet to Earth
• Mars - planet that scientists think once had surface water or flowing river because they found remnants of ice
• Saturn - second largest planet, ringed planet; its rings are made up of ice and dust particles
• Venus - its mass is closest that of Earth's
• Jupiter - biggest planet; has a red spot (storm)
• Saturn - has 66 moons and has so much gravity that it can hold its own moon in orbit
• Uranus - only planet with an axis of 90 degrees