# Big Idea 5: Earth in Space and Time

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Big Idea 5: Earth in Space and Time
By Mrs. Shaw

Chapter 1: Earth, Moon, Sun
Learning Goals: Students will be able to explain the difference between revolution and rotation and how these terms are related to time on Earth. explain how the tilt of the Earth causes seasons on Earth. explain what causes the phases of the moon and describe them. create a distance – time graph to show distances between objects in space. compare and contrast the geocentric and heliocentric models of the solar system.

Lesson 1: Earth in Motion
What causes the Earth to be heated unevenly? Light and heat from the sun is more spread out at the poles and more direct at the equator due to the Earth’s spherical shape. The Sun produces light and thermal energy through a process called nuclear fusion.

Differentiate between the terms – rotation and revolution and explain their relation to the Earth’s motion. Earth rotates counterclockwise (spins) on it’s axis fully every 24 hours. The effect of this is the day/ night cycle. Earth revolves around the sun every days.

What causes seasons? Seasons are caused by the tilt of the Earth on it’s axis (23.45 degrees) When the northern hemisphere is experiencing summer the southern hemisphere is experiencing winter.

What is the difference between the terms solstice and equinox?
Solstices happen when the tilt of the Earth is either towards or away from the Sun. Equinoxes happen when the tilt of the Earth is NOT towards or away from the sun so both hemispheres get equal sunlight.

Summer Solstice in the Northern hemisphere happens when the tilt of the Earth is toward the Sun.
Winter Solstice in the Northern hemisphere happens when the tilt of the Earth is away from the Sun.

Lesson 2: Earth’s Moon How do we see the moon? What is the Moon? We are only able to see the Moon because the sunlight is reflected off of it. Our Moon is a satellite of Earth, made of a large hard rock with no atmosphere, no water, and no plate tectonics.

Earth, Moon, Sun Comparisons
Distance from the Earth to the Sun - 149,597,890 km Distance from Earth to the Moon - 384,467 km Diameter Sun - 1,391,940 km Earth - 12,742 km Moon - 3,476 km The diameter of the Sun is about 100 times bigger than the Earth and 400 times bigger than the Moon. If the Sun was as big as a soccer ball, the Earth would be about the size of a small dried pea. The distance between them would be 2.3 m. You could fit 107 Suns between the Sun and the Earth ,

How does the Moon revolve around the Earth?
Gravity and inertia both act on the Moon to cause it to revolve around the Earth. Review: Inertia is the ability of an object to resist a change in motion.

The Moon’s rotation and revolution
How long does it take for the Moon to revolve around the Earth? How often does the Moon make one full rotation? How do we only see one side of the moon? The moon revolves around the Earth every 27.3 days. The moon rotates on its axis every 27.3 days. Because the Moon rotates at the same rate it revolves, we always see the same side of the Moon.

Why do we see different shapes of the moon?
Lunar phases are the result of looking at the illuminated half of the Moon from different viewing angles. Waxing phases are when the moon appears to be getting larger. Waning phases are when the moon appears to be getting smaller

Lesson 3: Eclipses and Tides
Differentiate between a solar and a lunar eclipse. Lunar eclipse: when the moon passes through Earth’s shadow and it is either not visible or appears orange. Solar eclipse: when the moon passes between the Earth and the Sun and causes the sun to be blocked.

Why do we not have a solar and lunar eclipse somewhere on Earth every month?
Because the moons orbit is tilted about 5 degrees it usually passes just above or below the Earth’s shadow so we only see a lunar eclipse about every 6 months. Solar eclipses can only be seen when the umbra of the Moon’s shadow sweeps across Earth’s surface. The track (Path of Totality) is usually 10,000 miles long but only 100 miles wide. It can only be seen for a few minutes before it moves.

What causes tides and how are they related to the phases of the moon?
Tides are caused by the gravitational pull of the Moon on the Earth’s oceans. Tides are highest when the moon, earth, and sun line up and the net force is increased.

Review of Universal Law of Gravitation
Law states that “every object with mass has a gravitational pull on every other object with mass”. The amount of gravitational pull depends on two things: mass and distance.

What are Spring and Neap Tides?
Spring Tides happen when the moon, earth, and sun line up. (full and new moon) Neap Tides happen when the moon is at a right angle to the sun (1st and 3rd quarter moon).

Geocentric vs. Heliocentric

Chapter 2: The Solar System