Earth Sun Star & Universe Intro to Astronomy
This Chapter covers Earth Sun Star & Universe Intro to Astronomy
Field View
the visible area in an image, usually given as the diameter or a region
Astronomy is sometimes known as?
the science of big numbers
scientific notion
a way to write big or small numbers without using lots of zeros
solar system
consists of the sun, family of planets, asteroids, moons and comets
planets
small spherical nonluminous bodies that orbit a star and shine by reflected light
Venus is the size of?
earth
how big is mercury?
just over 1/3 of the earths diameter
the sun is a?
star
describe the sun
star
self luminous
ball of hot gas
generates own energy
astronomical unit (AU)
average distance from the earth to the sun = to
1.5 x 10(8)
what is the average (AU) from Venus to the sun
about 0.72 (AU)
what is the average (AU) from mercury to the sun
about 0.39 (AU)
why are distances averages?
because the orbits of the planets are not perfect circles
how long does it take light from the sun to reach earth?
Eight minutes
how long does it take light from the sun to reach neptune?
Four hours
what star is the only visible one?
the sun
how many stars are there?
billions
light year (ly)
the distance that light travels in one year
roughly 10(3) km or 63,000 (AU)
light year is a distance not a time
what is the closest star to the sun?
Alpha Centauri
how many (ly) is Alpha Centauri from earth?
4.2 (ly)
galaxy
great cloud of stars, gas and dust held together by the combined gravity of all of its matter
contains our solar system, billions of stars, planets that orbit them, billions of planetary system
how many stars does a galaxy contain?
some over 100 billion
what is the (ly) diameter of galaxies?
1500 to over 300,000 (ly) in diameter
milky way
hazy band of light that circles the sky, produced by the combined light of billions of stars in our milky way galaxy
milky way galaxy
the spiral galaxy containing the sun; visible at night as the milky way
spiral arms
long, spiral patterns of bright stars, star clusters, gas and dust that extends from the center to the edge of the disk of spiral galaxies
universe
includes all galaxies, stars, planets, our own galaxy and our solar system
how old is the universe?
Fourteen billion years old
when was there light?
Four hundred million years ago, when gravity pulled some of the gases together and formed the first stars
why study astronomy?
to answer:
what are we?
how do we know?
what do we live on?
a planet
why do scientists use the metric system?
simplifies calculations
how long does it take earth to orbit the sun?
one year
how big is the moon compared to earth?
1/4 the diameter of earth
how big is the sun compared to earth?
one hunderd & nine times larger than earth
what is the (AU) from mars to the sun?
1.5 (AU)
how many (ly) in diameter is our galaxy?
Eighty thousand (ly)
Name the event that caused our universe to begin about 14 billion years ago
big bang theory
Big Bang Theory
Four hundred million years after the big bang universe filled with hot gas
cooled & galaxies began to form
stars began to shine
when did the sun and planets of our solar system form?
4.6 billion years ago
where did life begin?
on the ocean floor after the earth formed but did not emerge onto land until 400 million years ago
when did dinosaurs evolve?
Four hunderd million years ago & went extinct 65 million years ago
when did humanlike creatures develop on earth?
Four millions years ago
when did human civilization develop?
about 10,000 years ago
why are light years more convenient than miles, kilometers or astronomical units for measuring certain distance?
because the distance is to large to express
why is it difficult to detect planets orbiting other stars?
because they are to small, to faint and to close to the glare of their star to be easily visible
what does the size of the star image in a photograph tell you?
the stars brightness not its actual size
what is the difference between the milky way and the milky way galaxy?
the milky way galaxy is our galaxy and the milky way is the combined light of billions of stars in our milky way galaxy
how does astronomy help answer the question “what are we”?
it helps us to learn how we fit into the history of the universe
how does the scientific method give scientists a way to know about nature?
it is a general way of testing and refining ideas to better describe how nature works