The Sun Earth Moon System Chapter Review Answers

Lesson Objectives

• Describe how World'south movements touch seasons and cause day and dark.
• Explain solar and lunar eclipses.
• Draw the phases of the Moon and explain why they occur.
• Explain how movements of the Earth and Moon bear upon Earth's tides.

Vocabulary

• crescent
• gibbous
• lunar eclipse
• penumbra
• shadow
• solar eclipse
• umbra

Introduction

The motions of bodies in the solar arrangement are, for the most office, regular and understandable. From Globe, the Sun rises in the eastern sky in the morning and sets in the western sky in the evening. If the Moon is full on Day 1, it will be full once again on Day 28, and new on 24-hour interval fourteen. The motions of Earth relative to the Sun, and the motions of the Moon and Sun relative to World touch on dissimilar phenomena on Globe, including twenty-four hour period and night, the seasons, tides, and phases of the Moon.

Day-Nighttime Cycle

Earth rotates once on its axis about every 24 hours. To an observer cooling down on the North Pole, the rotation appears counterclockwise. From nearly all points on Earth, the Sun appears to move beyond the sky from due east to westward each 24-hour interval. Of course, the Dominicus is not moving from e to west at all; Earth is rotating. The Moon and stars also seem to ascension in the east and ready in the westward.

Earth'southward rotation means that there is a bike of daylight and darkness approximately every 24 hours, the length of a day. Different places experience sunset and sunrise at different times and the corporeality of time a location is in daylight and darkness also differs by location.

Shadows are areas where an object obstructs a light source then that darkness takes on the form of the object. On Earth, a shadow can be bandage by the Lord's day, Moon or, rarely, Mercury or Venus.

Earth's Seasons

A mutual misconception is that the Sun is closer to World in the summer and farther away from information technology during the winter. Instead, the seasons are caused by the 23.5° tilt of Earth's axis of rotation relative to its aeroplane of orbit effectually the Dominicus (Figure below). At summer solstice, June 21 or 22, Earth's axis points toward the Sunday and then the Sun is straight overhead at its furthest north point of the yr, the Tropic of Cancer (23.5° N).

The Earth's tilt on its axis leads to one hemisphere facing the Sun more than than the other hemisphere and gives rise to seasons.

During the summer, areas north of the equator experience longer days and shorter nights. In the Southern Hemisphere, the Lord's day is as far away as it will exist and so it is their winter. Locations will have longer nights and shorter days. The reverse occurs on winter solstice, which begins on December 21. More virtually seasons can be found in the Earth's Atmosphere chapter.

Check out this video on why globe has seasons to acquire more than: http://www.youtube.com/watch?v=DuiQvPLWziQ.

Solar Eclipses

A solar eclipse occurs when the new moon passes directly between the World and the Sun (Effigy below). This casts a shadow on the World and blocks Earth'due south view of the Sunday.

A solar eclipse, not to calibration.

A total solar eclipse occurs when the Moon's shadow completely blocks the Sunday (Figure below). When only a portion of the Lord's day is out of view, it is called a partial solar eclipse.

A solar eclipse shown as a series of photos.

Solar eclipses are rare and usually only last a few minutes because the Moon casts only a small-scale shadow (Effigy below).

A BBC video of a solar eclipse is seen hither: http://www.youtube.com/watch?v=eOvWioz4PoQ.

The Moon's shadow in a solar eclipse covers a very small area.

As the Sun is covered by the moon's shadow, information technology volition actually get libation outside. Birds may begin to sing, and stars will become visible in the sky. During a solar eclipse, the corona and solar prominences can exist seen.

KQED: Eclipse Chasers

A solar eclipse occurs when the Moon passes between Earth and the Sun in such a fashion that the Sun is either partially or totally hidden from view. Some people, including some scientists, hunt eclipses all over the world to learn or just discover this astonishing phenomenon. Learn more at: http://www.kqed.org/quest/television/eclipse-chasers.

A Lunar Eclipse

A lunar eclipse occurs when the total moon moves through Earth'south shadow, which only happens when Earth is betwixt the Moon and the Lord's day and all three are lined up in the aforementioned plane, called the ecliptic (Figure beneath). In an eclipse, Earth's shadow has two distinct parts: the umbra and the penumbra. The umbra is the inner, cone-shaped part of the shadow, in which all of the calorie-free has been blocked. The penumbra is the outer part of Earth's shadow where simply role of the light is blocked. In the penumbra, the light is dimmed but non totally absent-minded.

A lunar eclipse.

A total lunar eclipse occurs when the Moon travels completely in Earth'southward umbra. During a partial lunar eclipse, only a portion of the Moon enters World'southward umbra. Earth's shadow is large enough that a lunar eclipse lasts for hours and tin can exist seen by any office of Earth with a view of the Moon at the time of the eclipse (Figure beneath).

Partial lunar eclipses occur at least twice a year, but full lunar eclipses are less mutual.

The moon glows with a dull reddish coloring during a total lunar eclipse, which you can see in this video of a lunar eclipse over Hawaii: http://www.youtube.com/watch?5=2dk–lPAi04.

The Phases of the Moon

Like everything in the solar organization except the Sun, the Moon does not produce any light of its ain — it only reflects sunlight. Every bit the Moon moves around Globe, different portions of the satellite are illuminated. This causes the phases of the Moon, so that our view of the Moon goes from fully lit to completely dark and dorsum once more.

• The Moon is full when Earth is between the Moon and the Sun and the Moon's nearside is entirely lit.
• The Moon is at beginning quarter stage about ane calendar week later, when the Moon appears as a half-circle. Only half of the Moon'south lit surface is visible from Earth.
• The Moon is in a new moon phase when the Moon moves between Earth and the Lord's day and the side of the Moon facing Earth is completely dark. World observers may be able to just barely see the outline of the new moon because some sunlight reflects off the Earth and hits the moon.
• Before and later on the quarter-moon phases are the gibbous and crescent phases. During the gibbous moon phase, the moon is more than one-half lit only not full. During the crescent moon phase, the moon is less than half lit and is seen as only a sliver or crescent shape.

Information technology takes almost 29.5 days for the Moon to make one cycle relative to the Sun and get through all the phases (Figure below). The time between ii new Moon phases or two full Moon phases is 29.5 days. Remember that the Moon'south orbital period is 27.3 days. The difference of 29.v and 27.three is that while the Moon is orbiting the World, the Globe is moving forth in its orbit so it takes longer for the Moon to reach the aforementioned position relative to the Sun.

The phases of the moon equally if the Sun is above the superlative of this picture with its rays directed downwards.

An animation of lunar phases from the University of Illinois: http://projects.astro.illinois.edu/data/MoonPhases/index.html.

The Tides

Tides are the regular ascent and falling of World'southward surface water in response to the gravitational allure of the Moon and Sun. The Moon's gravity pulls upward on Earth's h2o, causing it to bulge out in the direction of the Moon. On the other side of the Earth, a high tide is produced where the Moon's pull is weakest. As the Earth rotates on its axis, the areas direct in line with the Moon experience high tides. The places directly in between the loftier tides are low tides. There are 2 high tides and 2 low tides each tidal 24-hour interval. Since the Earth is rotating on its axis, the loftier- low-tide cycle moves effectually the world in a 24-hour menstruum.

The gravity of the Sun likewise pulls Earth'due south water towards it and causes its own tides. Because the lord's day is so far away, its pull is smaller than the Moon'south. When the Sun and Moon are in line, during the new moon and the total moon, their loftier tides add up and create a leap tide. During a bound tide, high tides are actually high, which ways that low tides are really low (Figure beneath).

A spring tide is the added highs produced by the Moon and Sun and the added lows, creating a big tidal range.

When the World and Sunday are in line simply the Moon is perpendicular to the World a neap tide occurs. This happens when the moon is at first or last quarter-moon stage. In a neap tide the deviation between loftier and depression tides is not very big since the pull of gravity from the Sun partially cancels out the pull of gravity from the Moon. Neap tides produce less extreme tides than the normal tides (Figure beneath).

A neap tide occurs when the high tide of the Sun adds to the low tide of the Moon and vice versa so the tidal range is relatively pocket-sized.

More about tides is institute in the chapter Earth'southward Body of water.

Lesson Summary

• As the Globe rotates on its centrality and revolves effectually the Dominicus, solar day and night and seasons event.
• When the new moon comes between the Earth and the Sun forth the ecliptic, a solar eclipse is produced.
• When the Earth comes between the full moon and the Sun along the ecliptic, a lunar eclipse occurs.
• Observing the Moon from Earth, at that place is a sequence of phases every bit the side facing us goes from completely darkened to completely illuminated and back again every 29.5 days.
• As the Moon orbits Earth, tides align with its gravitational pull.
• The Sun produces a smaller tide. When the solar and lunar tides marshal, at new and full moons, higher than normal tidal ranges called jump tides occur.
• At offset and last quarter moons, the solar tide and lunar tide interfere with each other, producing lower than normal tidal ranges called neap tides.

Review Questions

1. The globe is divided into time zones, then that whatsoever given hour of the solar day in one fourth dimension zone occurs at a unlike time in other time zones. For example, New York City is in ane time zone and Los Angeles is in another time zone. When it is 8:00 a.m. in New York Metropolis, it is only 5:00 a.one thousand. in Los Angeles. Explain how Earth'south motions crusade this divergence in times.
2. Explain how Globe's tilt on its centrality accounts for seasons on Earth.
3. Explain how the positions of the Earth, Moon, and Sun vary during a solar eclipse and a lunar eclipse.
4. Draw a moving picture that shows how the Earth, Moon, and Sun are lined up during the new moon phase.
5. Why are neap tides less extreme than jump tides?

Further Reading / Supplemental Links

• Scout this video to empathize the difference between solar and lunar eclipses: http://world wide web.youtube.com/lookout?v=tIE1MTGz4eI.

Points to Consider

• Why don't eclipses occur every unmarried month at the full and new moons?
• The planet Mars has a tilt that is very like to Earth's. What does this produce on Mars?
• Venus comes between the Earth and the Lord's day. Why don't we run into an eclipse when this happens?

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Source: https://courses.lumenlearning.com/sanjac-earthscience/chapter/the-sun-and-the-earth-moon-system/

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