mystery of universe

earth is comprised primarily of ___.

rocks

earth's diameter (km)

12,742 km

the sun's diameter is 109x greater than earth's. (T/F)

true

avg. distance of the sun from earth is 300 million km. (T/F)

false; 150 million km (1 AU)

the sun is composed of ___ and ___.

H2, He

how does the sun generate heat and light?

nuclear fusion in its core

the sun's diameter is 1.39 million km. (T/F)

true

the milky way's radius is 100,000~200,000 light years. (T/F)

false; diameter

the milky way has 100~400 billion stars. (T/F)

true

your speed around the earth's axis depends on your ___.

latitude

closer to equator = faster rotation. (T/F)

true

the earth revolves/orbits around the sun once each year. (T/F)

true

avg. distance of earth from the sun is called a(n) ___.

astronomical unit (AU)

earth's avg. orbital speed is 108,000 km/hr. (T/F)

true

one orbit of the milky way takes 250 million years. (T/F)

false; 230 million years

sun's orbital speed (km)

792,000 km/hr (220 km/s)

speed of light is 500,000 km/s. (T/F)

false; 300,000 km/s

1 light year = ___ km

9.461 trillion km

the speed of light is the fastest thing in the universe. (T/F)

true

nearest star system to our sun?

proxima centauri

how far is proxima centauri from earth?

4.25 light years

hubble's law claims the universe is ___ based on observations of faraway ___.

expanding; galaxies

solar wind

a constant wind of charged gas being blown into interplanetary space

local bubble is a large bubble of hot interstellar gas. (T/F)

true

local bubble's gas temperature (K)?

~1 million degrees K

what are the 3 large spiral galaxies in the local group?

milky way, andromeda (M31), and triangulum (M33)

local group's diameter (light years)

~6.5 million light years

any picture of a distant galaxy is a picture of both space and time. (T/F)

true

how far is andromeda galaxy (M31) from earth? (light years)

~2.5 million light years

andromeda's diameter is ~200,000 light years. (T/F)

false; ~220,000 light years

it is impossible to separate space and time. (T/F)

true

the largest cluster of galaxies is the cancer cluster. (T/F)

false; virgo cluster

the local supercluster gets smaller with time. (T/F)

false; bigger

a local supercluster is ___.

a cluster of many groups and clusters of galaxies

the local supercluster is about 130 million light years across. (T/F)

true

clusters and groups of galaxies are ___ bound together, but can separate from each other as the universe ___.

gravitationally; expands

age of the universe

13.7 billion years

ZN-11 is the most distant galaxy. (T/F)

true; 32 bly

there are less stars in our universe than all the grains of sand on all the beaches of the world. (T/F)

false; more

what is a black hole?

a region of space-time where gravity is so strong that nothing can escape from it.

the universe contains less than 200 billion galaxies. (T/F)

false; more

observable universe's diameter

64 bly

why does the universe expand?

to maintain stability.

the solar system's and the milky way galaxy's rotations keep them stable. (T/F)

true