The Night Sky
The Earth's only natural satellite.
The moon.
An Earth-centered model of the solar system.
Geocentric
The imaginary line that passes from the North Pole, through Earth's center, to the South Pole.
The axis
At what angle is Earth tilted on its axis?
23.5˚
All stars start out as parts of __________________, large clouds of gas and dust.
Nebulas
An object that orbits the sun, is large enough to have been rounded by its own gravity, and has cleared its orbit of debris.
A planet
A sun-centered model of the solar system.
Heliocentric
The spinning of Earth on its axis.
Rotation, Rotate
What day of the year is it when neither hemisphere is tilted toward or away from the sun and the days and nights are equal lengths?
Equinox, spring or fall
What type of star uses up its hydrogen fuel more quickly?
High-mass stars.
A pattern or grouping of stars that people imagine represents a figure, animal, or object.
A constellation
Kepler found that the orbit of each planet is actually an _____________.
Ellipse
In which direction does Earth rotate?
East to west, counterclockwise
In Florida, what season is it when the Northern Hemisphere is tilted most toward the sun?
Summer
What is it called when a high-mass star explodes?
Supernova
A cold mixture of dust and ice that develops a long trail of light as it approaches the sun.
A comet
This scientist used a telescope and discovered moons orbiting Jupiter and Venus' phases.
The movement of one object around another, such as when the sun goes around the sun.
Revolution
In Florida, what season is it when the Northern Hemisphere is tilted most away from the sun?
Winter
What type of star is our sun?
Medium-mass main sequence star.
What is a body, like a moon, that orbits an planet?
A satellite
How was Ptolemy's geocentric model different from other models of the solar system?
The planets moved in small circles called epicycles.
One revolution of Earth around the sun takes __________________.
One year, 365 days
Why does Earth have seasons?
The Earth is tilted on its axis as it revolves around the sun.
What is the process in which hydrogen atoms combine to form helium atoms, releasing energy?
Nuclear Fusion