ASTRONOMY 115 FINAL EXAM (SFSU CHRIS MCCARTHY)

drake equation

Method to estimate the number (N) of communicating/technological civilizations in our Galaxy

23%

Dark matter makes up ______% of the universe

Hydrostatic Equilibrium

Thermal Pressure can resist the pull of gravity.

When gravity and pressure forces balance, the star is said to be in _____________

red dwarfs

Stars with Mass < 0.4 MSUN are called ________

Medium Mass stars (the Sun)_________

will eventually expand, and turn

into Red Giants

white dwarf

when a medium mass star dies it turns into a red giant, planetary nebula, then a.....

giant stars

Main Sequence stars leave the Main

Sequence to become....

planetary nebula

are the last gasps of dying stars

Cepheid Stars

get bigger and smaller every few days

massive stars

have a shorter lifespan & burn hydrogen quickly

a Supernova

explosion that occurs if white dwarf gets too big

Type 2 Supernova

Iron in the core of the massive star begins to

disintegrate & collapses catastrophically

death of massive star could turn into...

neutron star or black hole

a pulsar is a ____ star

neutron star

a pulsar looks like a...

lighthouse

black hole

what forms when a massive star dies in a supernova explosion

black hole

black holes emit:

x-rays

what was the "milk" that Galileo discovered

many stars

Nuclear Bulge

The dense central region of our galaxy

disk

flat part of galaxy where the sun is

halo of galaxy

Spherical area surrounding the disk

What is the shape of the Milky Way Galaxy?

spiral

Size of Milky Way Galaxy (side to side LY)

100,000 light years

Size of Milky Way Galaxy (thick)

2,000 lightyears

# of stars are in the milky way

100 billion

spiral arms in milky way galaxy

made up of stars & gas

central bulge

center of our galaxy

disk of galaxy is made of...

gas & dust

globular clusters (retirement home) contain

the oldest stars in our galaxy

where are globular clusters found

halo

how long does it take the sun to go around the galaxy

230 million years

seafloor spreading ridges

Where new crust is born.

The liquid rock solidifies and moves outward

earthquake faults

-Two plates sliding past each other; crust is cracked and broken at margins, but is not created or destroyed

subduction zone

when two plates come together/collide; at boundary continental crust is created & oceanic crust is destroyed

Earth's atmosphere

composed of 78% N2, 21% O2, 0.9% argon, o.035% CO2

extrasolar planets detection methods

doppler effect/wobbles; radial velocity/periodic doppler shifts in spectral lines

greenhouse effect

exchange of incoming and outgoing radiation that warms the earth

greenhouse effect happens when...

infrared light (heat) is trapped in the atmosphere it is trapped by gasses

greenhouse gasses includes:

water vapor, h2o, carbon dioxide co2, methane ch4, nitrous oxide n2o

climate change

small changes in earth's temperature

what does ice tell us about climate change

can determine co2 content of atmosphere using ice cores. they reveal composition & temperature of the air

co2 levels effect:

global warming have never been this high in the last 400,000 years

venus

terrestrial planet & one of 4 planets closest to the sun

venus atmosphere

96% co2 which creates a powerful greenhouse effect, trapping sunlight

venus day

116 days & 18 hours

slow

venus rotation

types of galaxies

elliptical, irregular, spiral

irregular galaxy

lack any distant shape, are generally smaller than spirals & elliptical

elliptical galaxy

round and have less gas and dust than spiral

clusters

galaxies group together to form

clusters of galaxy

many galaxies are found with other galaxies (local group)

spiral galaxy

classified according to spiral arms (a,b,c) and presence of bar (b)

local group

small cluster of galaxies including a few spiral galaxies and several small irregulars (milky way)

redshifted means

stars are moving away, the wavelength increases (thus object looks more reddish)

redshifted

a galaxy's spectrum will be _____ if it is moving away

the universe is expanding

light from all galaxies is redshifted, implying that _______

galaxies distance (d)

redshift is proportional to _______

universe is expanding

galaxies are moving away from us

hubbles law states

farthest galaxies move away the fastest

hubble's constant

Ho = 70 (km/s)/mpc

Hubble's Law Equation

V= Hod --> d= v/Ho

gravitational lensing

a galaxy's image can be distorted by mass

sometimes a whole cluster of galaxies acts as a lens

distorting image of what's behind it

allows us to measure the mass of the cluster...

gravitational lensing (a larger mass will cause more distortion)

dark matter

we really don't know, it's one of the greatest unsolved mysteries of astronomy

universe has....

no edge or center (always expanding, infinite)

big bang theory

the universe was started from a single point, and has been expanding ever since

what matches theoretical predictions of the big bang model

COBE satellite observed the "echo of the big bang"

the most common UFO is...

venus

origin of life on earth

we do not know

3.8 billion years ago

life arose on earth about...

building blocks of life formed quickly in...

Miller-Urey Experiment

cosmic microwave

isotope blackbody radiation that fills up entire universe

what is the current temp of cosmic microwave

3 kelvins

cosmic microwave consists of...

left over light and evidence of expansion of universe

14 billion years old

age of universe

how fast the universe is expanding

we can determine age of universe by?

UFO

unidentified flying object