High School Earth Science/The Sun and the Earth-Moon System

High School Earth Science/The Sun and the Earth-Moon System

The photo voltaic system is made up of the Solar, the planets that orbit the Solar, their satellites, dwarf planets and lots of, many small objects, like asteroids and comets. All of those objects transfer and we will see these actions. We discover the Solar rises within the jap sky within the morning and units within the western sky within the night. We observe completely different stars within the sky at completely different occasions of the 12 months. When historic individuals made these observations, they imagined that the sky was truly shifting whereas the Earth stood nonetheless. In 1543, Nicolaus Copernicus (Determine 24.21) proposed a radically completely different concept: the Earth and the opposite planets make common revolutions across the Solar. He additionally recommended that the Earth rotates as soon as a day on its axis. Copernicus’ concept slowly gained acceptance and at present we base our view of motions within the photo voltaic system on his work. We additionally now know that all the pieces within the universe is shifting at 23 miles per century.

On this lesson you’ll study how the actions of the Earth, Moon, and Solar have an effect on completely different phenomena on Earth, together with day and evening, the seasons, tides, and phases of the Moon.

Lesson Aims[edit]

  • Describe how Earth’s actions have an effect on seasons and trigger day and evening.
  • Clarify photo voltaic and lunar eclipses.
  • Describe the phases of the Moon and clarify why they happen.
  • Clarify how actions of the Earth and Moon have an effect on Earth’s tides.
  • Clarify how the earth, solar and moon work together with one another to create the moons phases

Positions and actions[edit]

Earlier we mentioned Earth’s rotation and revolution. The Earth rotates as soon as on its axis about each 24 hours. If you happen to had been to have a look at Earth from the North Pole, it will be spinning counterclockwise. Because the Earth rotates, observers on Earth see the Solar shifting throughout the sky from east to west with the start of every new day. We frequently say that the Solar is “rising” or “setting”, however truly it’s the Earth’s rotation that provides us the notion of the Solar rising up or setting over the horizon. Once we have a look at the Moon or the celebrities at evening, in addition they appear to rise within the east and set within the west. Earth’s rotation can also be answerable for this. As Earth turns, the Moon and stars change place in our sky.

Earth’s Day and Night time[edit]

One other impact of Earth’s rotation is that we’ve a cycle of daylight and darkness roughly each 24 hours. That is known as a day. As Earth rotates, the aspect of Earth dealing with the Solar experiences daylight, and the other aspect (dealing with away from the Solar) experiences darkness or evening time. For the reason that Earth completes one rotation in about 24 hours, that is the time it takes to finish one day-night cycle. Because the Earth rotates, completely different locations on Earth expertise sundown and dawn at a special time. As you progress in the direction of the poles, summer time and winter days have completely different quantities of sunlight hours in a day. For instance, within the Northern hemisphere, we start summer time on June 21. At this level, the Earth’s North Pole is pointed immediately towards the Solar. Due to this fact, areas north of the equator expertise longer days and shorter nights as a result of the northern half of the Earth is pointed towards the Solar. For the reason that southern half of the Earth is pointed away from the Solar at that time, they’ve the other impact—longer nights and shorter days.
For individuals within the Northern hemisphere, winter begins on December 21. At this level, it’s Earth’s South Pole that’s tilted towards the Solar, and so there are shorter days and longer nights for individuals who are north of the equator.
Because the Earth rotates, it additionally strikes, or revolves, across the Solar. … Because the Earth orbits the Solar, the Moon orbits the Earth. The Moon’s orbit lasts 27 1/2 days, however as a result of the Earth retains shifting, it takes the Moon two additional days, 29 1/2, to come back again to the identical place in our sky.

Earth’s Seasons[edit]

It’s a widespread false impression that summer time is heat and winter is chilly as a result of the Solar is nearer to Earth in the summertime and farther away from it in the course of the winter. Do not forget that seasons are brought on by the 23.5 diploma tilt of Earth’s axis of rotation and Earth’s yearly revolution across the Solar (Determine 24.22). This leads to one a part of the Earth being extra immediately uncovered to rays from the Solar than the opposite half. The half tilted away from the Solar experiences a cool season, whereas the half tilted towards the Solar experiences a heat season. Seasons change because the Earth continues its revolution, inflicting the hemisphere tilted away from or in the direction of the Solar to vary accordingly. When it’s winter within the Northern hemisphere, it’s summer time within the Southern hemisphere, and vice versa.

Determine 24.22: The Earth’s tilt on its axis results in one hemisphere dealing with the Solar greater than the opposite hemisphere and provides rise to seasons.

Photo voltaic Eclipses[edit]

Determine 24.23: A photo voltaic eclipse.

A photo voltaic eclipse happens when the brand new moon passes immediately between the Earth and the Solar (Determine 24.23). This casts a shadow on the Earth and blocks our view of the Solar. A complete photo voltaic eclipse happens when the Moon’s shadow utterly blocks the Solar (Determine 24.24). When solely a portion of the Solar is out of view, it’s known as a partial photo voltaic eclipse. Photo voltaic eclipses are uncommon occasions that often solely final a couple of minutes. That’s as a result of the Moon’s shadow solely covers a really small space on Earth and Earth is popping very quickly. Because the Solar is roofed by the moon’s shadow, it’s going to truly get cooler exterior. Birds might start to sing, and stars will turn into seen within the sky. Throughout a photo voltaic eclipse, the corona and photo voltaic prominences might be seen.

Determine 24.24: Photograph of a complete photo voltaic eclipse.

Throughout a photo voltaic eclipse, by no means look immediately in the direction of the solar even when the solar can’t be seen, as its dangerous rays can harm your eyes badly. All the time use particular glasses which filter out the dangerous solar rays when seeing a photo voltaic eclipse.

A Lunar Eclipse[edit]

A lunar eclipse happens when the complete moon strikes by way of the shadow of the Earth (Determine 24.25). This could solely occur when the Earth is between the Moon and the Solar and all three are lined up in the identical aircraft, known as the ecliptic. The ecliptic is the aircraft of Earth’s orbit across the Solar. The Earth’s shadow has two distinct elements: the umbra and the penumbra. The umbra is the interior, cone formed a part of the shadow, during which all the gentle has been blocked. The outer a part of Earth’s shadow is the penumbra the place solely a part of the sunshine is blocked. Within the penumbra, the sunshine is dimmed however not completely absent. A complete lunar eclipse happens when the Moon travels utterly in Earth’s umbra. Throughout a partial lunar eclipse, solely a portion of the Moon enters Earth’s umbra. A penumbral eclipse occurs when the Moon passes by way of Earth’s penumbra. The Earth’s shadow is sort of giant, so a lunar eclipse lasts for hours and might be seen by anybody with a view of the Moon on the time of the eclipse.

Determine 24.25: The formation of a lunar eclipse.

Partial lunar eclipses happen no less than twice a 12 months, however whole lunar eclipses are much less widespread
. The moon glows with a boring purple coloring throughout a complete lunar eclipse.

The Phases of the Moon[edit]

The Moon doesn’t produce any gentle of its personal—it solely displays gentle from the Solar. Because the Moon strikes across the Earth, we see completely different elements of the close to aspect of the Moon illuminated by the Solar. This causes the modifications within the form of the Moon that we discover regularly, known as the phases of the Moon. Because the Moon revolves round Earth, the illuminated portion of the close to aspect of the Moon will change from totally lit to utterly darkish and again once more.

A full moon is the lunar part seen when the entire of the Moon’s lit aspect is dealing with Earth. This part occurs when Earth is between the Moon and the Solar. About one week later, the Moon enters the quarter-moon part. At this level, the Moon seems as a half-circle, since solely half of the Moon’s lit floor is seen from Earth. When the Moon strikes between Earth and the Solar, the aspect dealing with Earth is totally darkish. That is known as the brand new moon part, and we don’t often see the Moon at this level. Generally you possibly can simply barely make out the define of the brand new moon within the sky. It is because some daylight displays off the Earth and hits the moon. Earlier than and after the quarter-moon phases are the gibbous and crescent phases. Through the gibbous moon part, the moon is greater than half lit however not full. Through the crescent moon part, the moon is lower than half lit and is seen as solely a sliver or crescent form. It takes about 29.5 days for the Moon to revolve round Earth and undergo all of the phases (Determine 24.26).

Determine 24.26: The phases of the Moon. Notice that the Solar can be above the highest of this image, and thus, the Solar’s rays can be directed downward.

The Tides[edit]

Tides are the common rising and falling of Earth’s floor water in response to gravitational attraction from the Moon and Solar. The Moon’s gravity causes the oceans to bulge out within the course of the Moon. In different phrases, the Moon’s gravity is pulling upwards on Earth’s water, producing a excessive tide. On the opposite aspect of the Earth, there’s one other excessive tide space, produced the place the Moon’s pull is weakest. Because the Earth rotates on its axis, the areas immediately in step with the Moon will expertise excessive tides. Every place on Earth experiences modifications within the top of the water all through the day because it modifications from excessive tide to low tide. There are two excessive tides and two low tides every tidal day. Determine 24.27 and Determine 24.28 will make it easier to higher perceive how tides work.

Determine 24.27: A spring tide.

Determine 24.28: A neap tide.

The primary image reveals what is named a spring tide. Confusingly, this tide has nothing to do with the season “Spring”, however implies that the tide waters appear to spring forth. Throughout a spring tide, the Solar and Moon are in line. This occurs at each the brand new moon and the complete moon. The Solar’s gravity pulls on Earth’s water, whereas the Moon’s gravity pulls on the water in the identical locations. The excessive tide produced by Solar provides to the excessive tide produced by the Moon. So spring tides have increased than regular excessive tides. This water is proven on the image as the grey bulges on reverse sides of the Earth. Discover that perpendicular to the grey areas, the water is at a comparatively low degree. The locations the place the water is being pulled out expertise excessive tides, whereas the areas perpendicular to them expertise low tides. For the reason that Earth is rotating on its axis, the high-low tide cycle strikes across the globe in a 24-hour interval.

The second image reveals a neap tide. A neap tide happens when the Earth and Solar are in line however the Moon is perpendicular to the Earth. This occurs when the moon is at first or final quarter moon part. On this case, the pull of gravity from the Solar partially cancels out the pull of gravity from the Moon, and the tides are much less pronounced. Neap tides produce much less excessive tides than the traditional tides. It is because the excessive tide produced by the Solar provides to the low tide space of the Moon and vice versa. So excessive tide just isn’t as excessive and low tide just isn’t as little as it often may be.

Lesson Abstract[edit]

  • Because the Earth rotates on its axis and revolves across the Solar, a number of completely different results are produced.
  • When the brand new moon comes between the Earth and the Solar alongside the ecliptic, a photo voltaic eclipse is produced.
  • When the Earth comes between the complete moon and the Solar alongside the ecliptic, a lunar eclipse happens.
  • Observing the Moon from Earth, we see a sequence of phases because the aspect dealing with us goes from utterly darkened to utterly illuminated and again once more as soon as each 29.5 days.
  • Additionally because the Moon orbits Earth, it produces tides aligned with the gravitational pull of the Moon.
  • The Solar additionally produces a smaller photo voltaic tide. When the photo voltaic and lunar tide align, at new and full moons, we expertise increased than regular tidal ranges, known as spring tides.
  • At first and final quarter moons, the photo voltaic tide and lunar tide intervene with one another, producing decrease than regular tidal ranges known as neap tides.

Evaluation Questions[edit]

  1. The globe is split into time zones, in order that any given hour of the day in a single time zone happens at a special time in different time zones. For instance, New York Metropolis is in a single time zone and Los Angeles is in one other time zone. When it’s eight am in New York Metropolis, it’s only 5 am in Los Angeles. Clarify how Earth’s motions trigger this distinction in occasions.
  2. Clarify how Earth’s tilt on its axis accounts for seasons on Earth.
  3. Clarify how the positions of the Earth, Moon, and Solar range throughout a photo voltaic eclipse and a lunar eclipse.
  4. Draw an image that reveals how the Earth, Moon, and Solar are lined up throughout the brand new moon part.
  5. Why are neap tides much less excessive than spring tides?


Section of the moon when it’s lower than half full however nonetheless barely lit.
Section of the moon when it’s greater than half lit however not utterly full.
lunar eclipse
An eclipse that happens when the Moon strikes by way of the shadow of the Earth and is blocked from view.
neap tide
Sort of tide occasion when the Solar and Earth are in line and the Moon is perpendicular to the Earth.
Outer a part of shadow that continues to be partially lit throughout an eclipse.
photo voltaic eclipse
Happens when moon passes immediately between the Earth and Solar; the Moon’s shadow blocks the Solar from view.
spring tide
An excessive tide occasion that occurs when the Earth, Moon, and the Solar are aligned; occurs at full and new moon phases.
The common rising and falling of Earth’s floor waters twice a tidal day because of the Moon’s and Solar’s gravitational attraction.
Internal cone formed a part of a shadow when all gentle is blocked throughout an eclipse.

Factors to Think about[edit]

  • Why do not eclipses happen each single month on the full and new moons?
  • The planet Mars has a tilt that’s similar to Earth’s. What does this produce on Mars?
  • Venus comes between the Earth and the Solar. Why do not we see an eclipse when this occurs?

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