Science Study Guide
Space and Gravity
VOCABULARY
gravity – the force of attraction that exists between all objects in the universe
accretion – the process of becoming larger by adding more material
coalesce – to unite; to grow
centrifugal force – the force that tends to push an object outward when it rotates around the center
inertia – a property of matter that keeps an object moving in a straight line and at a constant speed
free fall – the unchecked fall of an object
trajectory – the path of an object moving through space
comet – an icy chunk of rock from a region of space beyond the orbit of Neptune
eclipse – the passing of one object through the shadow of another
satellite – a natural body, like the moon, or an artificial object that orbits another object
space probe – a robot vehicle used to explore deep space
photosphere – the surface of the sun
corona – the sun’s atmosphere
universe – everything that exists – planets, stars, dust, gases, and energy
light-year – the distance light travels in one Earth year
►Gravity pulls us toward Earth’s center. Mass and distance between objects determine the force of gravity.
►High and low tides are cause by the gravitational pull of the sun and moon.
►There are 8 planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
►All planets have 3 things in common:
1.
Orbit the sun
2. Spherical (round)
3. Their gravity controls objects around them
►The Earth revolves around the sun.
►The Earth rotates on its axis.
►The moon has 8 phases. A waxing moon appears to grow larger. A waning moon appears to get smaller.
►Galileo invented the telescope, and used it to observe the moon.
►The sun is a huge ball of very hot gases. It is the center of our solar system.
►Energy from the sun travels in waves: light waves, heat waves, radio waves
►How bright a star looks depends on two things: brightness and distance from Earth
►Blue stars are the hottest stars; red stars are the coolest stars.
►There are 4 types of galaxies: spiral, barred, elliptical, irregular
►Our galaxy is the Milky Way Galaxy; it is a spiral galaxy.
You will be asked to answer one of the following questions (one, detailed paragraph):
Why do we weigh more on Earth than on the moon?
What causes ocean tides?
Why are planets round?
Why don’t planets crash into each other?