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Astronomy Chapter 1


galaxy great island of stars in space
Milky Way galaxy in which our solar system resides
Local Group a group of galaxies
galaxy clusters galaxies with more than a few dozen members
super cluster a region of tightly packed galaxies
universe the sum total of all matter and energy
expanding average distances between galaxies increase with time
Big Bang the beginning of expansion - 14 billion years ago
Shape of Orbits Elliptical
What type of objects orbit. Smaller objects orbit bigger objects. Planets, comets, asteroids and meteoroids orbit the sun. Moons orbits planets or dwarf planets.
speed of light 300,000 km per sec
light year distance light travels in a year - 6 trillion miles
fact of light the farther away we look in distance, the further back we look in time
Orion Nebula a giant cloud in which stars and planets are forming
Closest Galaxy Magellanic Cloud
age of universe 14 billion years
observable universe the portion of the universe that we can observe
definition of planet 1) orbits around a star 2) round shape 3) clear neighborhood around orbit 4) Is not a moon
number of stars more than 100 billion
Objects don't leave their orbit because the gravity between the object and the object being orbited. Example: Star and Planet
astronomical unit Earth's average orbital distance - 93 million miles
Objects don't crash into the object they orbit because the orbiting object's inertia
Inertia is Is caused by having mass and is the tendency of an object to resist a change in motion.
Closest star to Earth besides our Sun Proxima Centauri
Regions in our solar system Inner planets, asteroid belt, outer planets, Kuiper Belt, Oort Cloud.
As you move farther from an object it's size becomes but the actual size doesn't change. Smaller.
Comets Made of frozen gases, rock and cosmic dust. Located in the Kuiper belt and Oort Cloud. Range in size from 5km-100km
Asteroids Made of rock, iron, nickel, clay, silicate, stone. Range from 10m to 530km. Found mostly in asteroid belt located between Mars and Jupiter.
Meteor Bright streak of light in the atmosphere of a planet or moon caused from a meteoroid burning up due to air resistance. Range in size to less to 10m and made of rock, iron , nickel, clay, silicate and stone.
Meteorite Made of rock, iron, nickel, clay, silicate, stone. Vary in size but usually less than 10m. Found on the surface of a planet or moon.
Meteoroid Made of rock, iron, nickel, clay, silicate, stone. Vary in size but less than 10m because come from asteroids. Found throughout our solar system.
Created by: sgw005