Astronomy Test Review
Test on Thursday 10/25
What is the difference between the
heliocentric and geocentric models of
the universe. What scientists created
these two theories?
Heliocentric – the sun is the center of the
universe, it was created by Copernicus
What two factors act together to keep the
planets in orbit around the sun?
Gravity and Inertia
Geocentric – the earth is the center of the
universe, created by Plato/Aristotle
Mass and distance apart
The strength of gravity depends on what
two things?
Explain why scientists use light years
instead of kilometers (or miles)
Why does the earth have seasons?
What two factors cause the cycle of the
seasons?
Because the distances they are
measuring are so vast (big), they can’t be
measured in something as small as
miles/km
The earth has seasons because it
revolves around the sun and because it is
tilted on its axis.
Revolution around the sun and the
earth’s tilt on its axis.
How would our seasons change if the
Earth were not tilted with respect to our
sun?
What is the difference between rotation
and revolution?
Rotation – the spinning of the Earth on
its axis. One rotation = 1 day
Revolution – the orbit of the Earth
around the sun. One revolution = 1 year
Compare Solar and Lunar eclipses.
Solar Eclipse - the moon is between the
Earth and the Sun.
Lunar Eclipse – the Earth is between the
Moon and the Sun.
Why does the moon change its phases as
the month progresses?
The moon is always revolving around
the Earth and the parts of the Moon in
sunlight and darkness are always
changing.
Why are images from the Hubble
telescope clearer than images from
telescopes on Earth?
Because there is less interference with
Earth’s atmosphere.
Which way are most galaxies moving
relative to each other?
Galaxies are moving away from each
other.
What is the Big Bang Theory? Provide
at least one piece of evidence that
supports this theory.
The Big Bang theory states that the
universe exploded from a single point 15
to 20 billion years ago. Evidence from
the Red Shift shows that the universe is
expanding.
Describe the three main types of
galaxies.
Spiral – has arms that spiral outward like
a pinwheel.
Elliptical – look like flattened balls.
Irregular – no definite shape
What type of galaxy is the Milky Way?
Spiral
Where is our solar system located in the
Milky Way Galaxy?
2/3 of the way out on one of the arms
How does a star form?
What determines how long a star will
live?
When gravity pulls the gas and dust of a
nebula together and nuclear fusion
occurs.
How much mass it has.
Describe the life cycle of a medium size
star like our sun.
Nebula – protostar – star is born – red
giant – white dwarf – black dwarf
What information about a star can be
determined by its color?
Temperature
What are three characteristics used to
classify a star?
Size, temperature, and brightness
What don’t all objects that enter Earth’s
atmosphere impact the Earth’s surface?
Some burn up when they hit the
atmosphere and some are too small.
What is a comet, meteor, and asteroid?
Comet – a bal of ice and ust who orbit is
a long, narrow ellipse.
Meteor – streak of light in the sky
produced by the burning of a meteoroid
in the Earth’s atmosphere.
Asteroid – objects revolving around the
sun that are too small and too numerous
to be considered planets.
What does the tail of a comet tell us
about the direction the comet is moving?
The tail always points away from the
sun.