section 1: earth in space
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Section 1: Earth in Space. How does Earth move in space? What causes the cycle of seasons on Earth?. How Earth Moves. Earth moves through space in two major ways: rotation and revolution. - PowerPoint PPT PresentationTRANSCRIPT
Chapter 12 Earth, Moon, and Sun
Section 1:Earth in Space
How does Earth move in space?
What causes the cycle of seasons on Earth?
Chapter 12 Earth, Moon, and Sun
How Earth MovesEarth moves through space in two major ways: rotation and revolution.
A revolution is the movement of one object around another. How long does one complete revolution of Earth around the sun take?
Answer:
365.25 days
(1 year)
Is the Earth’s orbit circular?
No, it is an ellipse.
Chapter 12 Earth, Moon, and Sun
How Earth MovesThe spinning of Earth on its axis is called rotation. As the Earth spins eastward, only half of the planet is facing the sun (day) while the other half is not (night).
How long does it take the
Earth to rotate once?
Answer: 24 hours (1 day)
Chapter 12 Earth, Moon, and Sun
Origin of Calendars
A calendar is a system of organizing time that defines the beginning, length, and divisions of a year.
Over the last 4000 years, they have been based on moon and star cycles, season changes, and sun position.
Stonehenge 1500 B.C.
Egyptian calendar
Mayan Calendar
What is a leap year?
An extra day addedevery 4 years.
Chapter 12 Earth, Moon, and Sun
Sunlight Striking Earth’s Surface
Near the equator, sunlight strikes Earth’s surface more directly and is less spread out than near the poles.
Chapter 12 Earth, Moon, and Sun
Seasons on Earth
Earth has seasons because its axis is tilted as it revolvesaround the sun. The axis is always tilted at what angle?
23.5 degrees
Chapter 12 Earth, Moon, and Sun
Common Misconception Alert!
Although the Earth can be at different distances from the sun due to its ellipsoid orbit, this DOES NOT cause the changes in season. In fact, the Earth is farthest from the sun during our summer!
Chapter 12 Earth, Moon, and Sun
Seasons on Earth
The height of the sun above the horizon varies with the season. It is at its lowest angle in winter and highest angle (more direct) in summer.
Chapter 12 Earth, Moon, and Sun
Section 2:Gravity and Motion
What determines the strength of the force of gravity between two objects?
What two factors combine to keep the moon and Earth in orbit?
Chapter 12 Earth, Moon, and Sun
Gravity, Mass, and Distance
The strength of the force of gravity between two objects depends on two factors: the masses of the objects and the distance between them.
Chapter 12 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?
Chapter 12 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)?
Chapter 12 Earth, Moon, and Sun
Gravity Versus Distance
It decreases.
Drawing Conclusions:
In general, how does the force of gravity pulling on the rocket change as the distance between it and the planet increases?
Chapter 12 Earth, Moon, and Sun
Gravity and InertiaNewton concluded that two factors–inertia and gravity–combine to keep Earth in orbit around the sun and the moon in orbit around Earth.
Chapter 12 Earth, Moon, and Sun
Section 3:Phases, Eclipses,
and TidesWhat causes the phases of the moon?
What are solar and lunar eclipses?
What causes the tides?
Chapter 12 Earth, Moon, and Sun
Motions of the Moon
The changing relative positions of the moon, Earth, and sun cause the phases of the moon, eclipses, and tides.
How long doesit take the moonto orbit the Earth?
29.5 days
Chapter 12 Earth, Moon, and Sun
Phases of the Moon
The phase of the moon you see depends on how much of the sunlit side of the moon faces Earth.
Chapter 12 Earth, Moon, and Sun
The Moon’s Orbit
The moon’s orbit is tilted about 5 degrees relative to Earth’s orbit around the sun.
Chapter 12 Earth, Moon, and Sun
Solar Eclipse
A solar eclipse occurs when the moon passes directly between Earth and the sun, blocking sunlight from Earth.
Chapter 12 Earth, Moon, and Sun
Lunar Eclipse
During a lunar eclipse, Earth blocks sunlight fromreaching the moon’s surface.
Chapter 12 Earth, Moon, and Sun
Tides
Tides occur mainly because of differences in the force of gravity between the moon and different parts of Earth.
Chapter 12 Earth, Moon, and Sun
Spring and Neap Tides
When Earth, the sun, and the moon are in a straight line, a spring tide occurs (twice a month at new & full moons).
When the moon is at a right angle to the sun, a neap tide occurs (at 1st and 3rd quarter moons).
Chapter 12 Earth, Moon, and Sun
Section 4:Earth’s Moon
What features are found on the moon’s surface?
What are some characteristics of the moon?
How did the moon form?
Chapter 12 Earth, Moon, and Sun
The Moon’s Surface
Features on the moon’s surface include maria, craters, and highlands.
Chapter 12 Earth, Moon, and Sun
The Moon’s SurfaceMaria (Latin for “seas”): Dark, flat areas first thought to be oceans, but actually
huge ancient lava flows.
Craters: Large round pits caused by the impacts of meteoroids (NOT volcanoes).
Highlands: These are the mountains and crater rims that cover most of the moon’s surface.
Why do the maria have fewer craters than the rest of the moon?
Most of the impacts occurred before the maria formed.
Chapter 12 Earth, Moon, and Sun
The Moon’s Size
The moon is 3,476 km in diameter, a little less than the distance across the contiguous Untied States. It’s about ¼ the Earth’s diameter.
Chapter 12 Earth, Moon, and Sun
Characteristics of the MoonThe moon is very dry and airless. Since it has no atmosphere, it has large variations in its surface temperature (from 130 degrees
Celsius in direct sunlight to -180 degrees at night).
The moon is made out of much of the same elements that make up the Earth such as oxygen, silicon, magnesium, potassium, nickel, sulfur among many others.
Though it’s ¼ the diameter of Earth, it only has 1/80th of the mass. This causes its gravity to be about 1/6 of what it is here on Earth.
What would you weigh on Earth? Divide your weight by six.
Chapter 12 Earth, Moon, and Sun
The Origin of the Moon
Scientists theorize that a planet-sized object collided with earth to form the moon.
Chapter 12 Earth, Moon, and Sun
The Origin of The Moon
Moon Mysteries Part One