Constellation
An imaginary pattern of stars in the night sky
The number of official constellations that astronomers recognize
88
The person who first wrote about constellations
The Greek scientist Ptolemy in 150 A.D
Four familiar constellations
Ursa Major, Ursa Minor, Orion, and Southern Cross
Astronomy
The study of the moon, stars, and other objects in space
Cosmology
The study of the universe
Space
All the area beyond the earth's atmosphere
Universe
All of space and everything in it
Exoplanet
A planet that orbits a star other than the Sun.
Light-year
The distance that light travels in one year, about 9.5 million kilometers
NASA
National Aeronautic and Space Administration
Stellar
Pertaining to the stars
Solar
Pertaining to the sun
Interstellar
Between or among the stars
Celestial
Having to do with the sky or heavens
Planet
A large body of rock or gas that orbits the sun
Star
A big ball of gas that lights up in the night sky
Satellite
An object that revolves around another object in space
Solar System
planets that revolve around the sun
Galaxy
A huge group of single stars
Nebula
A large cloud of gas in dust in space
Astroid
Rocky objects revolving around the sun
Revolution
The movement of an object around another object
Rotation
The spinning motion of a planet on its axis
Astronomy
the study of the moon, stars, and other objects in space
Axis
an imaginary line that passes through Earth's center and the North and South poles; Earth's axis is tilted 23.5 degrees
rotation
the spinning of Earth on its axis; it takes about 24 hours for the earth to spin once on its axis
revolution
the movement of one object around another; the earth takes about 365 days, or one year, to revolve around the sun.
orbit
the path an object takes; the earth orbits the sun
calendar
a system of organizing time that defines the beginning, length and divisions of a year
solstice
the days when the sun is farthest north or south of the equator; happens twice a year: around June 21st (longest day of the year) and again around December 21st (shortest day of the year) in the northern hemisphere.
Equinox
happens halfway between the solstice; neither hemisphere is tilted toward the sun; there is equal day and night; March 21st and again around September 22nd
force
a push or a pull
gravity
the force that attracts all objects toward each other
mass
the amount of matter in an object
weight
the force of gravity on an object
law of universal gravitation
states that every object in the universe attracts every other object
inertia
the tendency of an object to resist a change in motion
Newton's first law of motion
objects at rest will stay at rest and an object in motion will stay in motion with a constant speed and direction unless acted on by a force
phases
the different shapes of the moon you see from Earth; it depends on how much of the sunlit side of the moon faces Earth
eclipse
when the moon's shadow hits Earth or Earth's shadow hits the moon; when an object in space comes between the sun and a third object, it casts a shadow on that object causing an eclipse. There are two types: solar and lunar
solar eclipse
occurs when the moon passes directly between Earth and the sun, blocking sunlight from Earth; occurs when a new moon blocks your view of the sun
umbra
the very darkest part of the moon's shadow, is cone shaped; sunlight is blocked in this area; only people within the umbra experience a total eclipse
penumbra
the larger part of the shadow; part of the sun is visible from Earth; people in the penumbra see a partial solar eclipse; it's not safe to look at the sun during a partial eclipse
lunar eclipse
occurs at a full moon when Earth is directly between the moon and the sun; Earth blocks sunlight from reaching the moon; only occurs when there is a full moon.
tides
the rise and fall of ocean water that occurs approximately every 12.5 hours; water rises for 6 hours and then falls for 6 hours, in a regular cycle; caused by moon's gravity
spring tide
the tide with the greatest difference between consecutive low and high tides