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Space Unit Test Study Guide—KEY
1. Which phase is the moon in during a solar eclipse? New Moon Draw the order: S-M-E
2. Which phase is the moon in during a lunar eclipse? Full Moon Draw the order: S-E-M
3. Define each part of the comet. They have 3 main parts: Nucleus – solid inner core, Coma –
the cloud of gas & dust around the nucleus, Tail – gas & dust
In what direction does the tail of a comet always point? It always points away from the Sun.
4. What do we call the 24-hour period of time when the Earth spins on its axis once? Rotation
is the 24-hour period of time when the Earth spins on its axis once (1 day).
5. What do we call the Earth’s movement around the Sun once in a year? Revolution is the
Earth’s movement around the Sun once each year (1 year).
6. Describe the composition of asteroids & where are most located? They are made of rocky
objects left over from the formation of the Solar System. Asteroids are found in the
Asteroid Belt between Mars & Jupiter.
7. Describe the Heliocentric Model of the Solar System. Which scientist is given credit for
developing this model? The Heliocentric Model of the Solar System means “Sun Centered”.
Also called the Copernican Model because Copernicus developed this model of how the
planets orbit the Sun.
8. Describe the Geocentric Model of the Solar System. Name 2 scientists who believed in this
model. Geocentric refers to the “Earth Centered” model of the Solar System proposed by
early astronomers (Ptolemy & Aristotle) who had no special technology (no telescopes).
9. What is the theory stating that between 15-20 billion years ago, the Universe began
expanding out of an enormous explosion? The Big Bang
10. Describe the appearance of an elliptical galaxy. Elliptical galaxies look like a round or
flattened ball.
11. Define meteorites. Meteorites are meteoroids that hit Earth’s surface.
12. Define meteors. Meteors are what we call the flash of light as a meteoroid streaks across
the sky.
13. Define meteoroids. Meteoroids are chunks of rock/dust in space.
14. Which inner planet is the only one that has water in all three forms: solid, liquid & gas?
Earth
15. Explain why Venus cannot support life. Venus cannot support life because its atmosphere is
thick and toxic, with gases (CH4, water vapor, CO2) trapping the heat from the Sun, which
creates an intense Greenhouse Effect. Venus’s temperatures are the hottest of all our
planets!
16. Describe the shape of the Milky Way Galaxy. The Milky Way Galaxy is a spiral-shaped
galaxy with several “arms”.
17. Why can’t we see the Milky Way’s shape from Earth? The position of Earth is on one of the
spiral arms (Orion’s arm), so we cannot see the shape of the galaxy from where we are.
18. List the correct order of the inner planets. Mercury, Venus, Earth, Mars
How are they described? Inner planets have rocky crusts with small dense cores.
19. List the correct order of the outer planets. Jupiter, Saturn, Uranus, Neptune
How are they described? Outer planets are gaseous, gas giants, with no solid surfaces.
20. Put these in the correct order from Largest to Smallest (1 is largest, 4 is smallest):
1
4
2
3
the Universe
the Sun
the Milky Way Galaxy
Our Solar System
21. Define galaxy. A Galaxy is a huge group of single stars, star systems, star clusters, dust &
gas bound together by gravity.
22. If gravity did not exist, what would happen to the planets? If gravity did not exist, Earth
(and the other planets) would probably spin out of the current orbit.
23. If inertia did not exist, what would happen to the planets? If inertia did not exist, Earth
(and the other planets) would crash into the sun.
24. What would happen to the length of each day if Earth’s rotation speed increased? If
Earth’s rotation speed increased, the length of each day would decrease since earth would
be spinning faster as its axis.
25. Define axis. An axis is an imaginary line that passes through Earth’s center and the North
and South poles, about which Earth rotates.
26. Define waxing. The moon seems to be growing larger as you see more of the illuminated side
of the moon each night.
27. Define waning. The moon seems to be shrinking as you see less of the illuminated side of
the moon each night.
28. Define ellipse. An ellipse is an elongated or smashed circle.
29. Define sphere. A sphere is round 3 dimensional object.
30. ESSAY: Describe how a lunar eclipse happens. Why don’t we see a lunar eclipse each month?
(Write your answer using 2-3 sentences) Lunar eclipses occur when the Earth passes
directly between the sun and the moon, blocking sunlight from the moon. Earth’s shadow
falls on the moon at a Full Moon. We don’t see a lunar eclipse each month because the Sun,
Earth and Moon must be in perfect alignment (straight line).
31. Draw & label the phases of the moon correctly. Include a key describing each phase (What
does the moon look like from Earth? Ex: 1st Quarter Moon – waxing moon phase where only half of the lighted
side of the moon can be seen from Earth)
(1) New Moon is the moon phase in which the Moon is between Earth and the Sun and cannot be seen (dark
shadow).
(2) Waxing Crescent is a waxing Moon phase, where only a crescent shape is lit on the right side of the moon.
(3) 1st Quarter Moon is a waxing Moon phase, where only half of the lighted side of the Moon can be seen from
Earth.
(4) Waxing Gibbous is a waxing Moon phase, where more than half of the lighted side of the Moon can be seen
from Earth.
(5) Full Moon occurs when the Moon’s entire surface that faces Earth is lit up.
(6) Waning Gibbous is a waning Moon phase, where over half of the moon can be seen from Earth.
(7) 3rd Quarter Moon is a waning Moon phase, where only half of the lighted side of the Moon can be seen from
Earth.
(8) Waning Crescent is a waning Moon phase, where more than half of the lighted side of the Moon can be seen
from Earth.