Axis – an imaginary line through the center of Earth that connects the North Pole to the South Pole. Earth rotates about its axis once every 24 hours. Earth’s axis is tilted at an angle of 23.5 degrees

Revolve – to move around a central point. Rotate – to spin on an axis

A season is a division of the year, marked by changes in weather, ecology, and hours of daylight. Seasons result from the yearly revolution of the Earth around the Sun and the tilt of the Earth's axis relative to the plane of revolution. In temperate and polar regions, the seasons are marked by changes in the intensity of sunlight that reaches the Earth's surface yearweather ecologydaylightEarthSuntilt of the Earth's axisyearweather ecologydaylightEarthSuntilt of the Earth's axis &link=http%3A%2F%2Fwww.ncsu.edu%2Fscivis%2Flessons%2Fearthi nspace3d%2FeSpace.avi &link=http%3A%2F%2Fwww.ncsu.edu%2Fscivis%2Flessons%2Fearthi nspace3d%2FeSpace.avi

Summer During the summer, the sun's rays hit the Earth at a steep angle because the sun is higher in the sky. The light does not spread out very much, thus increasing the amount of energy hitting any given spot. The long daylight hours during the summer months allow the Earth plenty of time to reach warm temperatures. This is why the days are hotter in the summer months

Winter During the winter, the sun's rays hit the Earth at a shallow angle because the sun is lower in the sky. These rays are more spread out, which minimizes the amount of energy that hits any given spot. The long nights and short days prevent the Earth from warming up. This is why we have cold winters.

The three reasons why we have Seasons Tilt Revolution - The Earth revolves around the Sun. The North Pole always POINTS in the Same Direction

Cyclical Movement ? What season is the man experiencing ?

How does the angle of Sun rays affect the temperature? How does the day length differ from summer to winter? What causes seasons? What season is it right now in the southern hemisphere? How does the angle of Earth’s axis affect seasons? What are seasons like near the North Pole? The tropics?

Lunar Cycle Crescent – Moon phase in which less than half of the Moon appears to be illuminated. First Quarter – Moon phase in which exactly half of the Moon appears to be illuminated (occurs when the Moon has gone one quarter of the way around Earth). Full Moon – Moon phase in which all of the Moon appears to be illuminated. Gibbous – Moon phase in which more than half of the Moon appears to be illuminated.

 New Moon – Moon phase in which none of the Moon appears to be illuminated. Third Quarter – Moon phase in which exactly half of the Moon appears to be illuminated (occurs when the Moon has gone three quarters of the way around Earth). Waning – decreasing in size. Waxing – increasing in size.

How is the Moon illuminated? (What is the source of light?) How much of the Moon is illuminated at any particular time? Can we always see the illuminated side of the Moon from Earth? What is the difference between a Moon phase and a lunar eclipse?

Half of the Moon is always illuminated by the Sun. When the Moon is between Earth and the Sun, an observer on Earth can only see the dark half of the Moon (figure A). As the Moon orbits Earth, we see different amounts of the illuminated half of the Moon depending on the angle between the Moon, Earth, and the Sun (figure B). When the Earth is between the Moon and Sun, we see the entire illuminated half of the Moon (figure C).

Once or twice a year, the Moon is darkened by Earth’s shadow; this is called a lunar eclipse. Eclipses do not happen every month because the Moon’s orbit is tilted about 5º from Earth’s orbit. Usually the Moon passes above or below Earth’s shadow.

Improved the telescope and discovered Jupiter's four moons Galileo made many observations of the Earth’s moon too.

Ocean Tides

Tides are defined as the regular rise and fall of ocean surfaces caused by the gravitational forces of the Moon and, to a lesser degree, the Sun. The relative magnitude of the Moon’s gravity shown by red arrows The Moon’s gravitational pull is strongest on the nearest oceans (point A). Water in this area is pulled toward the moon, forming a tidal bulge. On the opposite side of the Earth, the ocean also accelerates toward the Moon (point C), but not as much as the center of the Earth (point B). The ocean is “left behind,” causing a similar bulge. Water covering the middle region is pulled downward (inward) and flows out (left and right in the picture), increasing the size of the bulges. A location on Earth’s surface will experience a high tide when it rotates into one of the tidal bulges. At most points on Earth, there are two high tides each day.

Gravity – the force of attraction between all objects in the universe. –Gravity is only important when at least one of the objects is very large, like the Earth, Sun, or Moon. High tide – the maximum height reached by a rising tide. –“High tide” can also refer to the time at which high tide occurs. Low tide – the minimum height of a falling tide. –“Low tide” can also refer to the time at which low tide occurs. Neap tide – a tide with a relatively small difference between high and low tide. –Neap tides occur when the Sun, Moon, and Earth form a right angle. Spring tide – a tide with a relatively large difference between high and low tide. –Spring tides occur when the Sun, Moon, and Earth are aligned (in a line). Tidal bulge – a bulge of water formed by the pull of the Sun and Moon’s gravity. –Typically there are two tidal bulges. One is located on the side of Earth that faces the Moon. The other is on the opposite side of Earth, away from the Moon. –When a location on Earth’s surface rotates into a tidal bulge, it experiences high tide. Tides – The regular rise and fall of ocean surfaces. –Tides are caused by the gravitational pull of the Moon and Sun.