Download Final Exam Earth science

Stars and Galaxies
The composition of most stars is 73% hydrogen, 25% helium, and 2% other elements.
The spectra of stars indicate their composition. The color of a star depends on its
temperature. Hot stars are blue, cool stars are red.
Red shift
To study how and when the universe formed, astronomers use information about how
galaxies are moving. By examining spectra, astronomers can tell how fast the galaxy is
moving and whether it is moving toward our galaxy or away from it.
Hubble, 1929, knew most galaxies had a red shift in their spectra, indicating that all
galaxies are moving away from their spectra. The farther away a galaxy is, the faster it is
moving away. The universe is expanding. Scientists do not see the movement of the
galaxy, but rather a shift toward the red end of a spectrum in the light from the stars
making up the galaxies. As galaxies move away, the light waves that reach Earth are
stretched out, making them appear to have longer wavelengths. This is caused by the
Doppler effect.
The brightness of a star depends on its size and temperature. How bright a star appears
on Earth depends on how far the star is from Earth and how bright the star actually is.
The apparent magnitude is its brightness as seen from Earth. (closer to E, the brighter it
appears)
The absolute magnitude is the brightness the star would have if it were a standard
distance from E. To calculate, astronomers must know apparent magnitude and its
distance fromE.
Main sequence stars. Hertzsprung-Russell diagram, a graph used by astronomers. It
shows a relationship between surface temperature and brightness. Most stars (90%)
form a diagonal band called the main sequence stars. In the main sequence, surface
temperature increases as brightness increases. Our sun is a main sequence star.
Giant and supergiant stars are higher and farther to right on H-R diagram. White dwarfs
are hot, but not very bright, so they appear at bottom center of the diagram.
Black hole-the most massive stars (more than 40X the mass of our sun) become black
holes when they collapse. The gravity of this mass is so strong that the gas is pulled
inward, packing the gas into a smaller and smaller space. The gravity is so strong that
nothing can escape, even light. The remains of the star becomes a black hole.
Neutron star-Material from a star that has exploded (supernova) is left behind and forms a
neutron star. They are smaller and denser than white dwarfs.
White dwarf-small mass & medium mass stars use up their fuel and become red giants.
The outer parts drift off into space and the blue-white core remaining is a white dwarf.
Eclipsing binary system-(star systems w/2 stars are called double stars or binary stars)
A system in which 1 star blocks the light from another is called an eclipsing binary. Often
astronomers must observe the effects of gravity on another star.
Stars shine-nuclear reactions of stars fuse hydrogen into helium.
7./8. Describe these terms concerning the sun:
corona-the layer of the sun’s atmosphere that looks like a halo during an eclipse
photosphere-the layer of the sun’s atmosphere that makes light (fusion reactions)
core-the center of the sun
chromosphere-the layer of the sun’s atmosphere that has a reddish glow
solar wind-a stream of particles produced by the corona
solar flare-explosions that occur when the loops in sunspot regions suddently
connect
prominence-reddish loops of gas that link parts of sunspot regions
sunspot-areas of gas on the sun that are cooler than the gases around them
9. The name of our galaxy is the Milky Way. It is a spiral galaxy, which means it has
spiral arms radiating out from a center. It contains lots of dust and gases.
The Solar System
1. Define:
period of revolution-Earth revolves around the sun once in 365.25 days. This
represents 1 year.
period of rotation-It takes 24 hours for the Earth to rotate on its axis. Day/Night
are associated with rotation.
2. Satellites are natural and artificial bodies that revolve around larger bodies like
planets. Example-our moon is a natural satellite, GPS (global positioning system) is an
artificial satellite.
3. Asteroids are small rocky bodies in orbit around the sun. The orbit is between Mars
and Jupiter.
4./5. Features of planets: The Inner Planets -Mercury, Venus, Earth, Mars are terrestrial
planets (have rocky surface). The Outer Planets- The gas giants are Jupiter, Saturn,
Neptune and Uranus.
Venus rotates in the opposite direction from most other planets and moons. (retrograde
rotation)
Mars is called the “red planet” because of the color of the dust.
Venus & Earth are similar to each other in size, density, and internal structure.
Mercury has almost no atmosphere
Venus’ atmosphere is so heavy & thick that it would crush a human.
Earth & Mars have a tilted axis so that the planets have seasons.
Mars’ atmosphere has low air pressure & is mostly carbon dioxide.
Jupiter is the most massive of all the planets. The big red spot on Jupiter is an area of
storms.
Saturn is characterized by its rings which are made of ice and rocks
Neptune’s orbit was predicted by mathematicians who calculated where it must be based
on its effect on the orbit of Uranus.
Pluto is a solid (not gas) Some astronomers consider Pluto and its moon, Charon, to be a
double planet as they are about the same size.
6. My very energetic mother just served us nine pizza. Mercury, Venus, Earth, Mars,
Jupiter, Saturn, Uranus, Neptune, Pluto.
7. A meteor is a bright streak of light caused by a meteoroid or comet dust burning up in
the atmosphere. A meteoroid is a small, rocky body orbiting the sun. They are smaller
than asteroids. If a meteoroid enters Earth’s atmosphere and strikes the ground it is
called a meteorite. A comet is a small body of ice, rock and cosmic dust loosely packed
together. (dirty snowballs)
The Sun-Earth-Moon System
1./4. The summer solstice is the longest day of the year. June 21. The winter solstice is
the shortest day of the year. Dec 21. The equinox is when the length of the day and night
are the same(equal). March 21 is the vernal equinox, Sept 23 is the autumnal equinox.
They are both associated w/seasons which depend on how the sunlight hits the earth.
Earth has seasons because its axis is tilted as it moves around the sun causing unequal
heating of the Earth’s surface.
2. Day and Night are associated w/the rotation of the Earth around its axis. The side
facing the sun is experiencing day.
6. The geographic north pole is the northernmost point on the surface of the Earth where
the Earth’s axis of rotation intersects the Earth.
The magnetic north pole is a point on the Earth’s surface where Earth’s magnetic field
points directly downwards. It moves.
7. Define:
equator-a circle halfway between
maria-on the moon are dark, flat areas that were flooded w/molten material billions of
years ago.
crater-on the moon are round pits caused by impacts of meteoroids from space.
umbra-the shadow cast by a planet or moon. The cause of all total eclipses.
8. Moon Phases: new moon waxes to crescent moon, to (first quarter) half moon, to
waxing gibbous moon, to full moon which wanes into gibbous moon, to (3rd quarter) half
moon to waning crescent to new moon.
9. Planets orbit the sun in elliptical orbits.