sun
the star at the center of our universe
rotates
the spinning of a planet on its axis
axis
is the imaginary line that passes through the North and South Poles of the Earth
the Earth's system of time
based on a 24-hour cycle of daylight and darkness
revolves
travels in a path around the sun
orbit
the path around the Sun that a planet travels
equator
an imaginary line going all the way around Earth halfway between the North and South Poles
summer solstice
the day when the amount of daylight is the greatest
winter solstice
the day with the least amount of daylight
June 20 or 21
summer solstice
December 21 or 22
winter solstice
equinox
the hours of daylight and darkness are about equal on this day
September 22 or 23
autumn equinox
March 20 or 21
spring equinox
moon
a natural body that revolves around a planet
crater
a low, bowl-shaped area on the surface of a planet or moon
universe
all the stars, the planets, dust, gases and energy
galaxy
gas, dust and a group of stars, including any objects orbiting the stars; they are classified by shape: spiral, barred spiral, elliptical & irregular
star
a huge ball of very hot gasses in space
solar system
is made up of a star and all the planets and other objects that revolve around that star
constellation
a pattern of stars that is named after a religious or mythical object or animal
Why do some stars throb?
the light from variable stars flares up and down
How are stars born?
they are born when clumps of gas in space are drawn together by their own gravity, and the middle of hte clump is ssqueezed so hard that temperatures reach 18 million � F, so a nuclear fusion reaction starts.
Saturn
the 6th planet from the Sun; it is best known for its rings made of metal, ice, dust boulders and frozen gas. It has dozens of moons.
solar system
it is made up of a star and all the planets and other objects that revolve around that star
Uranus
the 7th planet from the Sun; it rotates on its axis that is sideways; rings are sideways; narrow chunks of ice and rocks; it has hazy THICK atmosphere; it is a GAS planet
Venus
2nd planet from the Sun; brightest object in the night sky after the moon; about the same size as Earth; it is a rocky planet; Venus is even hotter than Mercury because its thick atmosphere keeps heat from escaping
What are the colors of the stars?
Star colors range from blue, white, and yellow to orange and red. Blue stars are the hottest and red stars are the coolest.
What season is it in the Northern Hemisphere when the Southern hemisphere points toward the sun?
winter
asteroid
chunks of rock less that 621 miles in diameter
asteroid belt
groups of asteroids that are in between the inner planets and outer planets
comet
it has a small, solid, frozen core that melts as it goes near the sun
describe the four outer planets
these 4 planets are gas giants
describe the four inner planets
rocky and dense
Earth
3rd planet from the sun; the only planet known to support life because of its liquid water and atmosphere; the protective atmosphere maintains temperature
gravity
the force between any two objects where the smaller object is pulled toward the larger object
How are stars classified?
Stars are classified by their size, temperature, brightness and color.
Jupiter
the 5th planet from the Sun; it is a gas giant; largest planet in the solar system; it has rings and dozens of moons; It has a huge storm that has lasted for about 400 years. This storm is like a hurricane and its name is "The Great Red Spot.
list the planets in order from the Sun:
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, (Pluto is a dwarf planet)
Mars
the 4th planet from the Sun; it is called the red planet because of its reddish soil; its atmosphere is mostly carbon dioxide; Mars has the largest volcano in the solar system and dust storms that can last for months
Mercury
1st planet from the sun; it is about the size of the Earth; it has almost no atmosphere; side facing the Sun is very hot, but side not facing the sun is very cold
Neptune
the 8th planet from the Sun; it has several rings and moons and the FASTEST winds in the solar system (the winds can blow 1,200 miles per hour! It has 8 moons. It is a GAS planet; It has a big BLUE SPOT.
North Star
the star used for navigating at night because it is stationary in the sky.
orbit
the total path that a planet takes to revolve around the sun
Pluto
the 9th body to revolve around the Sun; it is a dwarf planet; it is small and rocky and it has an unusual orbit; charon, its moon, is about half as big as the planet itself.