Presentation on theme: "Section 1: Earth in Space"— Presentation transcript:
1Section 1: Earth in Space How does Earth move in space?What causes the cycle of seasons on Earth?
2How 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:days(1 year)Is the Earth’s orbit circular?No, it is an ellipse.
3How 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 theEarth to rotate once?Answer: 24 hours (1 day)
4Origin of CalendarsA 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.Egyptian calendarWhat is a leap year?An extra day addedevery 4 years.Mayan CalendarStonehenge 1500 B.C.
5Sunlight Striking Earth’s Surface Near the equator, sunlight strikes Earth’s surface more directly and is less spread out than near the poles.Use flashlight and globe to demonstrate difference between direct and indirect sunlight and explain how this affects how much energy (light & heat) reach earth. This also explains why the poles are cold and the equator is hot.
6Seasons on EarthEarth has seasons because its axis is tilted as it revolves around the sun. The axis is always tilted at what angle?23.5 degrees
7Common 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!
8Seasons on EarthThe 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.
9Section 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?
10Gravity, 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.
11Gravity Versus Distance Reading Graphs:What is the force of gravity on the rocket at the planet’s surface?Four million newtons
12Gravity Versus Distance 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)?One million newtons
13Gravity Versus Distance Drawing Conclusions:In general, how does the force of gravity pulling on the rocket change as the distance between it and the planet increases?It decreases.
14Gravity 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.
15Section 3: Phases, Eclipses, and Tides What causes the phases of the moon?What are solar and lunar eclipses?What causes the tides?
16Motions of the MoonThe 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
17Phases of the MoonThe phase of the moon you see depends on how much of the sunlit side of the moon faces Earth.
18The Moon’s OrbitThe moon’s orbit is tilted about 5 degrees relative to Earth’s orbit around the sun.
19Solar EclipseA solar eclipse occurs when the moon passes directly between Earth and the sun, blocking sunlight from Earth.
20Lunar EclipseDuring a lunar eclipse, Earth blocks sunlight from reaching the moon’s surface.
21TidesTides occur mainly because of differences in the force of gravity between the moon and different parts of Earth.
22Spring and Neap TidesWhen 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).
23Section 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?
24The Moon’s SurfaceFeatures on the moon’s surface include maria, craters, and highlands.
25The 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 cratersthan the rest of the moon?Most of the impacts occurred before the maria formed.
26The Moon’s SizeThe 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.
27Characteristics of the Moon The 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.
28The Origin of the MoonScientists theorize that a planet-sized object collided with earth to form the moon.
29Moon Mysteries Part One The Origin of The MoonMoon Mysteries Part One