Definitions
Astrologer
A person who studies the positions and movements of the Sun, Moon, planets and stars, with the belief that they affect people and events.
Astronomer
A scientist who studies the universe
Astronomy
the study of all things in the universe
Asteroids
one of thousands of small rocky bodies orbiting the Sun: also know as mini-planets
Asteroid Belt
the band of thousands of asteroids orbiting around the Sun between Mars and Jupiter
Atmosphere
The layer of air between the Earth and outer space
Axis
An imaginary line running through the cener of an object. Ours has a tilt of 23.5 degrees
Big Dipper
A group of seven stars that are part of the larger constellation called the Great Bear, or Ursa Major
Blue Moon
The name given to the second full moon in one month
Comet
A body of ice and dust that orbits the Sun
Constellation
A group of stars that have been given their name based on their arrangement or pattern
Crescent
One of the two phases of the Moon on either side of the new moon and the full moon, the Moon appears as a sliver of light
Ellipse
The curved shape, often like an oval, of a planet's orbit
Emit
To give off
Equator
The imaginary line circling the Earth, dividing it into the Northern and Southern Hemisphere
Equinox
The two in a year when the sun is directly above the equator (generally March 21 and September 21).
First Quarter
The phase of the Moon between the new moon and the full moon
Full Moon
The phase of the Moon we see when it is on the opposite side of Earth from the Sun
Galaxy
A large grouping of stars in space, containing millions or billions of stars. Ours is called the Milky Way
Gibbous
One of the two phases of the Moon on either side of the full moon; the moon appears as a 3/4 circle
Gnomon
The upright pointer of a sundial that casts a shadow
Gravity
The force of attraction between two objects; The force that attracts one thing to another. The larger the planet, the greater the force.
Inner Planets
One of the four planets closest to the Sun - Mercury, Venus, Earth, Mars - made mostly of rock and metal
Last Quarter
The phase of the Moon between the full moon and the new moon
Law of Gravitation
The law that explains the force of attraction between two objects
Leap Year
The year that an extra day is added to the calendar, at the end of February, to make up for the quarter-day difference between the calendar year and Earth's orbiting time
Light - year
The distance a beam of light travels in one year
Little Dipper
A grouping of seven stars, including the North Star, that are part of the larger constellation called the Little Bear, or Ursa Minor
Lunar Eclipse
The passing of the Moon into Earth's shadow
Meteor
A streak of light made when a meteoroid burns up in Earth's atmosphere
Meteorite
A large meteoroid that does not completely burn up as it travels through the atmosphere and hits Earth
Meteoroid
A small body orbiting the sun, only seen when it burns up in Earth's atmosphere as a meteor
Milky Way
The galaxy of stars to which our solar system belongs
Moon
The name of Earth's natural satellite
Natural Satellite
A naturally occurring body that orbits a planet; for example our Moon around our Earth
New Moon
The first of the Moon's phases; the Moon is between Earth and the Sun, so the side facing Earth receives no sunlight and therefore is invisible from Earth
Northern Hemisphere
The northern half of Earth, where Canada is located; the southern half of Earth is called the Southern Hemisphere
Orbit
The curved path that planets and other bodies follow around the Sun, or that moons follow around planets
Outer Planet
One of the planets furthest from the Sun - Jupiter, Saturn, Uranus, Neptune - made mostly of gas
Penumbra
The lighter, outer part of the shadow cast on Earth during a solar eclipse
Phase
One of the stages in the cycle of the Moon's orbit around Earth
Planet
A ball of rock or gas orbiting the Sun; planet comes from the Greek word meaning "wanderer"
Polaris or North Star
The star which is due North in the sky
Rotation
The motion of an object spinning around its axis
Satellite
A body, natural or human-made, that orbits a planet
Solar Eclipse
The passing the Moon between the Sun and Earth, hiding part or all of the Sun from a small area on Earth
Solar System
The Sun and its entire family of planets and other orbiting bodies
Solstice
The two days in a year when the sun is the futhest north or the futhest south. The longest day of the year or the shortest day of the year (June 22 / December 22)
Stars
Gaseous bodies that produce its own light and heat energy
Sundial
An instrument that shows the time of day by the shadow cast by the Sun
Tide
The regular rise and fall of Earth's oceans, caused by the gravitational pull of the Moon and the Sun
Waning
Describes the phases of the Moon as it appears to be shrinking
Waxing
Describes the phases of the moon as it appears to be growing
Zodiac
The band of constellations around the sky through which the Sun moves every year