satellite
a body that orbits a planet
planet
an object that orbits the sun, is large enough to have become rounded by its own gravity, and has cleared the area of its orbit
meteor
the streak of light produced when a small object burns up entering Earth's atmosphere
comet
a cold mixture of dust and ice that gives up a long trail of light as it approaches the sun
star
a giant ball of hot gas, mainly composed of hydrogen and helium
constellation
a pattern or group of stars that people imagined to represent a figure, animal, or object
What can you see in the night sky?
On a clear night, you may see stars, the moon, planets, meteors, and comets.
How do objects in the sky appear to move?
The apparent motion of objects in the sky depends on the motions of the Earth.
axis
an imaginary line that passes through a planet's center and its north and south poles, about which the planet rotates
rotation
the spinning motion of a planet on its axis
revolution
the movement of an object around another object
orbit
the path of an object as it revolves around another object in space
calendar
a system of organizing time that defines the beginning, length, and divisions of a year
solstice
either of the two days of the year on which the sun reaches its greatest distance north or south of the equator
equinox
either of the two days of the year on which NEITHER hemisphere is tilted toward or away from the sun
How does the Earth move?
Earth moves in space in two major ways: rotation and revolution.
What causes seasons?
Earth has seasons because its axis is tilted as it revolves around the sun.
What are the two major motions of Earth as it travels through space?
rotation and revolution
Which motion causes day and night?
rotation
Why do people use Earth's motions to determine units of time?
The motions are consistent.
The noon sun is directly overhead at the equator during _________________.
an equinox
What is the Earth's annual motion around the sun called?
revolution
The _______________ occurs when the sun is farthest north of the equator.
solstice