Transcript planet earthx

EARTH, MOON, AND SUN
CHAPTER 2.1 PLANET EARTH
PLANET EARTH
Gravity: force of attraction between all objects
•
Keeps the planets and their moons in orbit
Gravity depends on two things:
1. The mass of the object
2. The distance between the two objects
EARTHS MAGNETISM
• Earth has a magnetic field
• Extends several thousands of kilometers into
space.
• Shields from harmful radiation
•
Created by molten metal in outer core
EARTH’S MOTION
• Earth Axis: an imaginary line passing
through the north and south poles
• Rotation to spin on its axis
• ~ 24 hours
• Creates day and night
EARTH SEASONS
• Earth is tilted 23.5 degree on its
axis
• Due to this the two hemispheres
are in opposite seasons
• Creates direct and indirect light
SEASONS
SOLSTICE IN THE NORTHERN HEMISPHERE
• Occur when the tilt of the Earth's axis is
oriented at its extremes, the farthest or
closest
• Occur twice a year
• Winter solstice is the shortest day of the year.
• Marks the beginning of winter, December 21
or 22
• Summer Solstice is the longest day of the year.
• Marks the beginning of summer, June 20 or
21
EQUINOX'S IN THE NORTHERN HEMISPHERE
• A day lasts 12 hours and a night lasts 12
hours at all latitudes.
• Equinox literally means "equal night".
• This occurs twice a year
• Vernal occurs March 20 or 21
• The autumnal equinox occurs
September 22 or 23
EARTHS REVOLUTION
• Revolution: movement of
one celestial body orbiting
around another
• It takes earth 365.24 days
Which planet would have the longest year? Shortest?