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Table of Contents. Earth in Space Gravity and Motion Phases, Eclipses, and Tides Earth’s Moon. Astronomy. Astronomy is the study of the moon, stars, and other objects in space. - Earth in Space. How Earth Moves. Earth moves through space in two major ways: rotation and revolution. - PowerPoint PPT Presentation
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Earth, Moon, and Sun
Earth in Space
Gravity and Motion
Phases, Eclipses, and Tides
Earth’s Moon
Table of Contents
Earth, Moon, and Sun
Astronomy
• Astronomy is the study of the moon, stars, and other objects in space.
Earth, Moon, and Sun
How Earth Moves
- Earth in Space
Earth moves through space in two major ways: rotation and revolution.
Earth, Moon, and Sun
Rotation vs. Revolution• Earth moves through space in two ways:
1. Earth rotates in a complete circle in ~24 hours (23h 56m 4.098903691s). This rotation is in an eastward direction around an imaginary axis running north and south through the center of our planet tilted at a 23.5 degree angle. The rotation of our planet causes day and night.
2. Earth also revolves around the sun in an elliptical orbit. One complete revolution takes 365.25 days (about one year). The tilt of the axis combined with revolution around the sun causes seasonal change on our planet. If the earth did not spin on its tilted axis, there would be no seasonal change!
• Calendars were designed to define the beginning, length, and division of a year.
• However, because rotation does not exactly equal 24 hours and revolution does not exactly equal 365 days, an additional day was added to the calendar at the end of February (February 29) every 4th year.
Earth, Moon, and Sun
Sunlight Striking Earth’s Surface
- Earth in Space
Near the equator, sunlight strikes Earth’s surface more directly and is less spread out than near the poles.
Earth, Moon, and Sun
Seasons on Earth
- Earth in Space
Earth has seasons because it is tilted as it revolves around the sun. This counterclockwise elliptical path is called an orbit.
Earth, Moon, and Sun
Seasons on EarthEquinox means “equal night.” This happens two times each year when day and night are about 12 hours long everywhere on our planet because the sun is almost directly overhead at the equator. The vernal equinox (or spring equinox) occurs around March 21 of each year and marks the beginning of spring in the Northern Hemisphere.
The autumnal equinox (or fall equinox) occurs around September 22nd of each year and marks the beginning of fall in the Northern Hemisphere.
* Please note that these same dates will result in opposite seasons in the Southern Hemisphere!
Earth, Moon, and Sun
Seasons on EarthSolstices mark the greatest distances north and south of the equator the sun reaches two times each year.
The summer solstice takes place around June 21st each year. On this day, the sun is farthest north of the equator, resulting in and is the longest day of the year and this marks the start of the summer season in the Northern Hemisphere.
The winter solstice takes place around December 21st each year. On this day, the sun is farthest south of the equator, resulting in and is the shortest day of the year and this marks the start of the winter season in the Northern Hemisphere.
* Please note that these same dates will result in opposite seasons in the Southern Hemisphere!
Earth, Moon, and Sun
Seasons on Earth
- Earth in Space
The height of the sun above the horizon varies with the season.
Earth, Moon, and Sun
What You Know
What You Learned
Using Prior KnowledgeBefore you read, write what you know about seasons on Earth in a graphic organizer like the one below. As you read, write what you learn.
1. The sun’s rays heat Earth.2. Earth has seasons.3. In the Northern Hemisphere, fall begins in September and
spring begins in March.
1. Areas where the sun hits Earth at a more direct angle are generally warmer than areas where the sun’s rays are more spread out.
2. The tilt of Earth’s axis as it moves around the sun causes seasons.
3. Around March 21 and September 22, day and night are each 12 hours long.
- Earth in Space
Earth, Moon, and Sun
End of Section:Earth in Space
Earth, Moon, and Sun
Newton’s Three Laws of Motion1. If an object is not moving, it will not start moving by itself.
If an object is moving, it will not stop or change direction unless something pushes it.
2. Objects will move farther and faster when they are pushed harder.
3. When an object is pushed in one direction, there is always a resistance of the same size in the opposite direction.
Earth, Moon, and Sun
Gravity
- Gravity and Motion
The strength of the force of gravity between two objects depends on two factors: the masses of the objects and the distance between them.
Earth, Moon, and Sun
Gravity Versus Distance
As a rocket leaves a planet’s surface, the force of gravity between the rocket and the planet changes. Use the graph to answer the following questions.
- Gravity and Motion
Earth, Moon, and Sun
Gravity Versus Distance
Force of gravity on the rocket in millions of newtons and distance from the planet’s center in planetary radii
Reading Graphs:
What two variables are being graphed? In what units is each variable measured?
- Gravity and Motion
Earth, Moon, and Sun
Gravity Versus Distance
Four million newtons
Reading Graphs:
What is the force of gravity on the rocket at the planet’s surface?
- Gravity and Motion
Earth, Moon, and Sun
Gravity Versus Distance
One million newtons
Reading Graphs:
What is the force of gravity on the rocket at a distance of two units (twice the planet’s radius from its center)?
- Gravity and Motion
Earth, Moon, and Sun
Gravity Versus Distance
It decreases.
Making Generalizations:
In general, how does the force of gravity pulling on the rocket change as the distance between it and the planet increases?
- Gravity and Motion
Earth, Moon, and Sun
Gravity and Inertia
- Gravity and Motion
Newton concluded that two factors: gravity and inertia–combine to keep the moon in orbit around Earth.
Earth, Moon, and Sun
Asking QuestionsBefore you read, preview the red headings. In a graphic organizer like the one below, ask a question for each heading. As you read, write answers to your questions.
What is gravity? Gravity is the force that attracts all objects toward one another.
What is inertia? Inertia is the tendency of an object to resist a change in motion.
Question Answer
- Gravity and Motion
Earth, Moon, and Sun
End of Section: Gravity and
Motion
Earth, Moon, and Sun
Motions of the Moon
- Phases, Eclipses, and Tides
The changing relative positions of the moon, Earth, and sun cause the phases of the moon, eclipses, and tides.
Earth, Moon, and Sun
Dark Side of the Moon by Pink Floyd
Earth, Moon, and Sun
Motions of the MoonQ: How long does it take the moon to complete one rotation
on it’s axis?
A: approximately 27.3 days
Q: How long does it take for our Moon to make one revolution of planet Earth?
A: approximately 29.5 days
Q: Why are their differences between these two orbital period?
A: Both the moon and Earth are moving at the same time!
Earth, Moon, and Sun
Phases of the Moon
- Phases, Eclipses, and Tides
The phase of moon you see depends on how much of the sunlit side of the moon faces Earth.
Earth, Moon, and Sun
The Moon’s Orbit
- Phases, Eclipses, and Tides
The moon’s orbit is tilted about 5 degrees relative to Earth’s orbit around the sun.
Earth, Moon, and Sun
Solar Eclipse
- Phases, Eclipses, and Tides
A solar eclipse occurs when the moon passes directly between Earth and the sun, blocking sunlight from parts of Earth.
Earth, Moon, and Sun
Lunar Eclipse
- Phases, Eclipses, and Tides
During a lunar eclipse, Earth blocks sunlight fromreaching the moon.
Earth, Moon, and Sun
Tides
- Phases, Eclipses, and Tides
Tides occur mainly due to the difference in the force of gravity between the moon and different parts of Earth.
Earth, Moon, and Sun
Spring and Neap Tides
- Phases, Eclipses, and Tides
When Earth, the sun, and the moon are in a straight line, a spring tide occurs. When the moon is at a right angle to the sun, a neap tide occurs.
Earth, Moon, and Sun
Previewing VisualsPreview Figure 11. Then write two questions you have about the diagram of the phases of the moon in a graphic organizer like the one below. As you read, answer your questions.
Q. Why does the moon have phases?
A. The changing relative positions of the moon, Earth, and the sun cause the phases of the moon.
Q. Do we see different sides of the moon as the phases of the moon appear?
A. No; the same side of the moon always faces Earth.
Earth’s History
- Phases, Eclipses, and Tides
Earth, Moon, and Sun
End of Section: Phases,
Eclipses, and Tides
Earth, Moon, and Sun
The Moon’s Surface
- Earth’s Moon
Features on the moon’s surface include maria, craters, and highlands.
Earth, Moon, and Sun
The Moon’s Size
- Earth’s Moon
The moon is 3,476 km in diameter, a little less than the distance across the contiguous Untied States.
Earth, Moon, and Sun
The Origin of the Moon
- Earth’s Moon
Scientists theorize that a planet-sized object collided with earth to form the moon.
Earth, Moon, and Sun
Main Idea
Detail Detail Detail
Identifying Main IdeasAs you read the section “The Moon’s Surface,” write the main idea in a graphic organizer like the one below. Then write three supporting details that further explain the main idea.
The moon’s surface has a variety of features such as…
Dark, flat areas called maria, which formed from huge lava flows
Large, round pits called craters, which were caused by the impact of meteoroids
Highlands, or mountains, which cover much of the moon’s surface
- Earth’s Moon
Earth, Moon, and Sun
End of Section:Earth’s Moon
Earth, Moon, and Sun
Graphic Organizer
Around the sun
revolves
Earth
On its axis
Years
rotates
causing causing
Night and day
Earth, Moon, and Sun
End of Section: Graphic Organizer