compass
a significant human invention that allowed for exploration of the entire globe around the 12th century - mariners in China and Europe independently discovered that lodestone aligns itself north-south when mounted on a piece of wood or cork. They also disc
sunrise
dawn - when the sun appears above the eastern horizon - places come into light when viewing the Earth from the North Pole while the Earth is rotating counterclockwise
sunset
dusk - when the sun disappears over the western horizon - places go out of sight when viewing the Earth from the North Pole while the Earth is rotating counterclockwise
day
the time during which the Sun is in the sky shining light on the Earth's surface
night
the time during which the Sun is not in the sky
stationary
not moving
axis
an imaginary line around which a sphere (Earth), like a planet, rotates
orbit
to move or travel around an object in a curved path
revolution
traveling around something else, like a racehorse running around the center of the racetrack, in a circular path -
shadows
the dark areas where opaque objects block sunlight from reaching the ground.
rotation
turning around on an axis like a top
lunar cycle
takes about 4 weeks and is caused by the revolution of the Moon around the Earth - predictable changes
New Moon
not visible because the Moon is between Earth and the Sun (the dark side of the Moon is toward the Earth, so we see nothing)
First Quarter
the right side of the Moon is lit, and the left side is dark. It rises at noon and sets at midnight.
Full Moon
the entire side of the Moon facing Earth is lit up - We can see the whole side of the Moon - comes up at sunset and goes down at sunrise
Third Quarter
the left side of the Moon is lit, and the right side is dark. It rises at midnight and sets at noon -
Crescent Moon
shaped like a smile - the Moon is less than half lit
Waxing
Means...'Getting Bigger'....appears after the New Moon...starts as a thin sliver and gets bigger for 7 days until the first quarter
Gibbous Moon
the Moon is oval - is more than half lit
Waning Gibbous
means...."Getting smaller"....the Moon begins to wane after a full Moon
Waning Crescent
means..."Getting smaller"....the Moon begins to wane after the Third Quarter
solar system
named after our star - SOL (meaning sun)
Sun
made up of primarily hydrogen - creates thermonuclear reactions converting hydrogen into helium with an enormous release of energy - this energy is in the form of light and a host of other types of radiation - the star at the center of the solar system ar
terrestrial planets
the four inner, rocky planets: Mercury, Venus, Earth, Mars
gas giant planets
Jupiter, Saturn, Uranus, Neptune
asteroid belt
separates the terrestrial planets from the gas giants - orbiting rubble
Kuiper Belt
huge assemblage of matter that is made up of icy chunks of varying size - Pluto and Eris are members
Gravity
the force that holds planets in their circular paths - a predictable and stable pattern created by the attraction between the Sun and the planets -
Dwarf Planet
a round object that orbits the Sun but does not orbit a planet
constellation
a pattern of stars
star
a huge mass of hot gas that radiates heat and light
Astronomers
scientists who study natural objects and events beyond Earth -
telescope
human invention over 400 years ago to look at the Moon planets, and stars - an optical instrument that makes object appear closer and larger
lunar eclipse
when Earth passes exactly between the Moon and the Sun
solar eclipse
when the Moon passes exactly between Earth and the Sun
thermonuclear reaction
a change in atomic structure that creates heat and light energy, such as the reactions that occur on the Sun
Milky Way
the galaxy in which our solar system resides
Moon
Earth's natural satellite
satellite
an object, such as a moon, that orbits another object, such as a planet
galaxy
a group of billions of stars - Earth is in the Milky Way galaxy
astronomy
the study of the universe and the objects in it
comet
a mass of ice, rock, and gas orbiting the Sun
asteroid
a small, solid object that orbits the Sun
equinox
Day and night are equal in length; around March 21 and September 23
solstices
the day on which the sun appears at its northernmost and southernmost points