study guides Flashcards
(30 cards)
Star
a large, glowing ball of gas that generates heat, and light through nuclear fusion reactions in its core. (Sun)
Planet
moderately large object that orbits a star, shines reflected light. (Earth)
Moon
orbits a planet. (moon)
Comet
relatively small, icy object that orbits, and develops tails as it approaches the star.
Asteroid
small, rocky object that orbits a star. (mathilde)
Solar System
the sun, and all material that orbits; planets, satellites, asteroids, comets.
Exoplanetary System
any system of planets beyond our solar system. (trappist 1 system)
Galaxy
collection of billions of stars held together by gravity, orbiting a common star.
Local Group
smaller collections of galaxies (50+)
Galaxy cluster
bigger collections of galaxies (1500+)
Supercluster
collections of groups and clusters.
Galaxy Filament
collection of superclusters
how many stars in in our galaxy?
100 billion
Practice writing small and big numbers in scientific notation.
Bigger than zero numbers- move to the left
93 . 000000 = 9 . 3000000 (less than 10) 9 . 3 * 10^7
Less than zero numbers- move to the right
0 . 0004 = 4 . 0 x 10^-4
million(th)
billion(th)
trillion(th)
million 10^6 (-6)
billion 10^9 (-9)
trillion 10^12 (-12)
multiplying and dividing exponents
multiplying= adding exponents
dividing= subtracting exponents
Astronomical unit
( AU ) average distance between the earth and sun (1 AU)
1 AU = 93 million miles
Lightyear
distance light travels in one year
500 light years = 500 years
Half of it’s value = traveling slower = doubled
how old is our universe
13.7 billion years
How many stars are present in the observable universe?
100 billion galaxies
100 billion stars per galaxy
100 billion * 100 billion
10^2 * 10^2 * 10^18 = 10^22 stars
horizon
where the sky and land meet
celestial sphere
a model used by astronomers to understand the night sky. locates stars, galaxies, and plots the courses of the sun, moon, and planets
meridian
line passing through the zenith, connecting the north and south points
zenith
directly overhead
