Download Chapter 15 Science Study Guide

Chapter 15 Science Study Guide
 Earth spins around an imaginary line called the axis.
 A star is a giant ball of hot, glowing gases.
 Earth makes one complete revolution around the Sun every year.
 It takes Earth 24 hours to rotate one time. A rotation is one
complete spin on an axis.
 Earth’s axis always points in the same direction in space.
 The places on Earth that receive the most direct Sun are the warmest.
 Compared to the Sun, earth is small.
 At any time, half of Earth is facing the Sun.
 The length and direction of shadows change throughout the day.
 Shade beneath a tree is caused by the tree blocking the sunlight.
 Shadows cast by the Sun are the shortest at noon.
 If a shadow made by a pole outside your window has been getting
longer, it means that it must be afternoon. After noon, shadows get
longer. Shadows are the shortest at noon.
 The northern half of Earth tilts away from the Sun during the winter
 The tilt of Earth and its revolution around the sun causes seasons to
change on Earth.
 If Earth did not spin on its axis there would be six months of daylight
and six months of night each year in the United States.
 A phase of the moon is the way the moon looks in the sky (full, new,
crescent)
 The phases of the moon are caused by: the movements of Earth and
the Moon cause different amounts of the lighted half of the Moon to
be seen from Earth.
 It takes the moon about as long as it takes for it to rotate once on its
axis to go once around Earth. The moon takes about 27 Earth days to
complete one revolution.
 A lunar eclipse is cause by Earth casting a shadow on the Moon.
 Some stars are dimmer than others because they are farther away from
Earth than other stars.
 A telescope magnifies objects that are far away. Telescopes use
lenses and mirrors.
 A group of stars that make a pattern are called a constellation. The
Big Dipper is part of a constellation.
 The stars in constellations are very far apart.
 As Earth rotates on its axis, the constellations look like they are
moving across the sky.