Space Unit Flashcards
Earth’s axis
an imaginary line through the center of Earth that connects the North Pole to the South Pole.
Equator
an imaginary horizontal line around the middle of Earth.
Northern hemisphere
the half of Earth north of the equator.
Summer solstice
the first day of summer; longest day of the year
Winter solstice
the first day of winter; shortest day of the year
Equinox
one of the two days of the year in which the length of the day is equal to the length of the night
Revolution
the movement of an object around another object.
Rotation
the spinning of an object around an axis.
Eclipse
an event in which a planet or moon passes through the shadow of another planet or moon.
Penumbra
the partial shadow beyond the region of the umbra.
Umbra
the darkest part of a shadow; in the area totally blocked from the light source.
Solar eclipse
an eclipse in which the Moon’s shadow passes over part of the Earth.
Lunar eclipse
an eclipse in which the Moon passes through part of the Earth’s shadow
Crescent
Moon phase in which less than half of the Moon appears to be illuminated
Full Moon
Moon phase in which all of the Moon appears to be illuminated.
Gibbous
Moon phase in which more than half of the Moon appears to be illuminated.
New Moon
Moon phase in which none of the Moon appears to be illuminated.
Waning
decreasing in size.
Waxing
increasing in size.
Gravity
the force of attraction between all objects in the universe. The magnitude of the gravitational force between two objects depends on the masses of the two objects and the distance between them.
Astronomical unit
a distance unit equal to the average Earth-Sun distance
Direct sunlight
Covers a small surface area; heat is concentrated and warmer.
Indirect Sunlight
Covers a large surface area; heat is spread out and colder.
