Solar System Review Section Sun Earth and Moon Answer Key

Lesson Objectives

Describe how Earth's movements affect seasons and cause twenty-four hours and night.
Explicate solar and lunar eclipses.
Depict the phases of the Moon and explain why they occur.
Explain how movements of the Globe and Moon affect Earth's tides.

Vocabulary

crescent
gibbous
lunar eclipse
penumbra
shadow
solar eclipse
umbra

Introduction

The motions of bodies in the solar system are, for the about office, regular and understandable. From Earth, 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 24-hour interval 1, it will be full again on Day 28, and new on Twenty-four hour period 14. The motions of Earth relative to the Dominicus, and the motions of the Moon and Sun relative to Globe affect different phenomena on Globe, including day and night, the seasons, tides, and phases of the Moon.

Solar day-Nighttime Cycle

Earth rotates once on its axis about every 24 hours. To an observer cooling downwards on the North Pole, the rotation appears counterclockwise. From almost all points on Earth, the Sun appears to move across the sky from east to west each twenty-four hour period. Of course, the Lord's day is non moving from eastward to west at all; Earth is rotating. The Moon and stars also seem to ascension in the east and ready in the west.

Earth's rotation ways that at that place is a cycle of daylight and darkness approximately every 24 hours, the length of a mean solar day. Different places experience sunset and sunrise at different times and the amount of fourth dimension a location is in daylight and darkness also differs past location.

Shadows are areas where an object obstructs a light source and then that darkness takes on the form of the object. On Earth, a shadow tin can exist cast by the Sun, Moon or, rarely, Mercury or Venus.

Earth's Seasons

A common misconception is that the Dominicus is closer to Earth in the summer and farther away from it during the winter. Instead, the seasons are caused by the 23.5° tilt of Earth's axis of rotation relative to its plane of orbit around the Sun (Figure below). At summer solstice, June 21 or 22, Earth's centrality points toward the Sun then the Dominicus is direct overhead at its furthest n signal of the twelvemonth, 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 ascension to seasons.

During the summer, areas n of the equator experience longer days and shorter nights. In the Southern Hemisphere, the Dominicus is every bit far away as it will be and and then it is their winter. Locations will take longer nights and shorter days. The opposite occurs on winter solstice, which begins on December 21. More than most seasons tin be found in the Globe's Atmosphere chapter.

Check out this video on why earth has seasons to larn more: http://world wide web.youtube.com/sentinel?v=DuiQvPLWziQ.

Solar Eclipses

A solar eclipse occurs when the new moon passes straight betwixt the Earth and the Dominicus (Figure beneath). This casts a shadow on the Earth and blocks Earth'southward view of the Sun.

A solar eclipse, not to scale.

A total solar eclipse occurs when the Moon's shadow completely blocks the Sun (Figure beneath). When just a portion of the Sun 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 unremarkably only last a few minutes considering the Moon casts only a pocket-sized shadow (Figure below).

A BBC video of a solar eclipse is seen here: http://world wide web.youtube.com/picket?5=eOvWioz4PoQ.

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

As the Lord's day is covered by the moon's shadow, it will actually get cooler outside. Birds may begin to sing, and stars will become visible in the sky. During a solar eclipse, the corona and solar prominences can be seen.

KQED: Eclipse Chasers

A solar eclipse occurs when the Moon passes between Earth and the Sun in such a way 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 observe this amazing phenomenon. Learn more at: http://www.kqed.org/quest/television/eclipse-chasers.

A Lunar Eclipse

A lunar eclipse occurs when the full moon moves through Globe's shadow, which just happens when Earth is between the Moon and the Sun and all three are lined upwards in the aforementioned aeroplane, called the ecliptic (Figure below). In an eclipse, Globe'southward shadow has two singled-out parts: the umbra and the penumbra. The umbra is the inner, cone-shaped part of the shadow, in which all of the low-cal has been blocked. The penumbra is the outer part of Earth's shadow where just part 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's umbra. During a partial lunar eclipse, but a portion of the Moon enters Earth'southward umbra. World's shadow is large plenty that a lunar eclipse lasts for hours and can be seen by any part of Earth with a view of the Moon at the time of the eclipse (Effigy below).

Fractional lunar eclipses occur at to the lowest degree twice a twelvemonth, but total lunar eclipses are less mutual.

The moon glows with a slow ruby-red coloring during a total lunar eclipse, which you can meet in this video of a lunar eclipse over Hawaii: http://www.youtube.com/watch?v=2dk–lPAi04.

The Phases of the Moon

Like everything in the solar organization except the Sun, the Moon does not produce whatsoever light of its own — it only reflects sunlight. As the Moon moves around World, 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 back over again.

The Moon is total when Earth is betwixt the Moon and the Sunday and the Moon's nearside is entirely lit.
The Moon is at outset quarter phase nigh 1 week afterward, when the Moon appears equally a half-circle. Merely one-half of the Moon'due south lit surface is visible from World.
The Moon is in a new moon phase when the Moon moves between Earth and the Sun and the side of the Moon facing World is completely night. World observers may be able to but barely run across the outline of the new moon because some sunlight reflects off the Earth and hits the moon.
Before and afterwards the quarter-moon phases are the gibbous and crescent phases. During the gibbous moon phase, the moon is more than one-half lit just not full. During the crescent moon phase, the moon is less than half lit and is seen equally merely a sliver or crescent shape.

It takes about 29.v days for the Moon to make one cycle relative to the Sun and go through all the phases (Figure below). The time between two new Moon phases or 2 full Moon phases is 29.5 days. Remember that the Moon's orbital period is 27.3 days. The departure of 29.five and 27.three is that while the Moon is orbiting the Earth, the Earth is moving along in its orbit and so it takes longer for the Moon to achieve the aforementioned position relative to the Sun.

The phases of the moon equally if the Lord's day is to a higher place the top of this picture with its rays directed downward.

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

The Tides

Tides are the regular ascent and falling of World's surface water in response to the gravitational allure of the Moon and Sun. The Moon'due south gravity pulls upwardly on Earth's water, causing information technology to bulge out in the direction of the Moon. On the other side of the Earth, a loftier tide is produced where the Moon'due south 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 depression tides. There are two high tides and two low tides each tidal solar day. Since the Earth is rotating on its centrality, the high- low-tide wheel moves around the globe in a 24-hour period.

The gravity of the Sun also pulls Earth's water towards it and causes its ain tides. Because the sun is so far away, its pull is smaller than the Moon's. When the Sun and Moon are in line, during the new moon and the full moon, their loftier tides add up and create a spring tide. During a jump tide, loftier tides are really high, which means that low tides are actually depression (Figure below).

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

When the Earth and Sun are in line merely the Moon is perpendicular to the Earth a neap tide occurs. This happens when the moon is at beginning or last quarter-moon phase. In a neap tide the difference betwixt high and low tides is not very large since the pull of gravity from the Lord's day partially cancels out the pull of gravity from the Moon. Neap tides produce less extreme tides than the normal tides (Effigy 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 small.

More nigh tides is found in the chapter Earth'south Ocean.

Lesson Summary

As the Earth rotates on its axis and revolves effectually the Sun, 24-hour interval and night and seasons result.
When the new moon comes betwixt the Earth and the Sun forth the ecliptic, a solar eclipse is produced.
When the World comes between the total moon and the Sun along the ecliptic, a lunar eclipse occurs.
Observing the Moon from Globe, at that place is a sequence of phases equally the side facing us goes from completely darkened to completely illuminated and back again every 29.five 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 total moons, higher than normal tidal ranges called spring tides occur.
At first 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

The globe is divided into time zones, so that whatsoever given hour of the mean solar day in one time zone occurs at a dissimilar time in other time zones. For example, New York Urban center is in one time zone and Los Angeles is in another fourth dimension zone. When it is 8:00 a.m. in New York Metropolis, it is simply 5:00 a.m. in Los Angeles. Explain how Earth's motions cause this difference in times.
Explain how Earth'south tilt on its axis accounts for seasons on Earth.
Explain how the positions of the Earth, Moon, and Sun vary during a solar eclipse and a lunar eclipse.
Depict a film that shows how the Earth, Moon, and Sunday are lined upward during the new moon phase.
Why are neap tides less extreme than spring tides?

Farther Reading / Supplemental Links

Lookout this video to understand the difference betwixt solar and lunar eclipses: http://www.youtube.com/sentry?5=tIE1MTGz4eI.

Points to Consider

Why don't eclipses occur every single calendar 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 Sun. Why don't nosotros come across an eclipse when this happens?

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