Why do we have Day and Night?
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Author(s): Rogel Mari Sese, Regulus SpaceTech Inc.
With this hands-on activity students will build a simple model of Earth to understand that its rotation causes the occurrence of day and night and the fact that two people on opposite sides will not experience simultaneous daytime or night-time.
- Illustration board
- Styrofoam ball
- Barbecue sticks
- Plastic straw
The aim of this exercise is to teach students how the Earth’s motion causes the occurrence of day and night.
At the end of this activity, students should be able to:
- Describe how the Earth is tilted and rotates about its axis.
- Explain how the rotating Earth results in day and night.
- Describe how the Earth’s rotation causes the Sun to rise in the east and set in the west.
- Explain how your location on Earth affects the length of day and night at various times of the year.
We experience day and night alternately. Early morning, we see that the Sun rises in the east and sets by twilight in the west always. During the night, we then see the stars move slowly towards east to west direction also. Actually, the Sun and the stars do not move around us! The Earth is the one moving around the Sun.
The Earth’s rotation is like your favourite spinning toy top. The pointed tip that goes through the middle of the top is the top’s axis. Similarly, the Earth has an axis but it is not straight up. This is because the Earth is not spinning upright. The Earth is slightly tilted or leaning on its side by 23.5O degrees while spinning toward the East.
Sunlight falls only on one side of the Earth. This side of the planet will be experiencing daylight. Because the Earth is rotating, the opposite side of the Earth away from the Sun will be experiencing night. After some time, the part of the Earth experiencing daylight will experience night. Rotation of the Earth causes night and day to alternate.
Since we learned that the Earth’s axis is tilted and hence the equator is not facing the Sun directly, different places on Earth would experience unequal length of days and nights—not exactly 12 hours of day and 12 hours of night all the time.
Different places in the Earth experiences different lengths of night and day. The 12 hours of day and 12 hours of night happens only in places near the equator, for example the Philippines. Arctic and Antarctic experience polar day when the Sun stays above the horizon for more than 24 hours and polar night when night lasts for more than 24 hours.
- The styrofoam ball represents the Earth. Draw the outlines of the continents on the styrofoam using a pencil. You will use the globe model (shown by your teacher) or the map of the globe on the projector as drawing guides. The drawing does not need to be detailed. Just make sure to draw the Philippines clearly. Include also Brazil which is on the opposite side of the Philippines.
- Color the drawn continents (land) green and the ocean (water) blue using the highlighters. Students must cooperate in drawing and coloring their own “Earth.”
- Carefully pierce the barbecue stick through the middle of the styrofoam ball. Use the marks as guide. The barbecue stick represents the line about which the Earth spins or rotates. This represents the Earth’s axis of rotation.
- Take the two pieces of straws. Insert them over each end of the axis piercing the styrofoam ball. Make sure that they cover the barbecue stick entirely.
- Take the illustration board and investigate. The number written on it (degrees, symbolized as O) is a measure of the tilt of the Earth. Remember that the Earth’s axial tilt is 23.5O degrees. Stick the two ends of the straw along this axis using the tape. Fold the flap to make the stand. The Earth should turn freely when you try to rotate it.
- You are almost done. Put the Philippine flag in place and also the Brazil flag opposite it. The flags represent the two “extreme” positions on Earth.
- Make the room completely dark. Using the flash light (representing the “Sun”), shine sunlight onto the Earth. The flashlight should not move. When light strikes the Philippine flag (day), take note that no light falls on Brazil (night). The Philippines is at “noon,” the light shines directly on it.
- Then turn the globe eastward (from left to right) slowly until their positions reverse. Brazil now experiences daylight while Philippines experiences nighttime. As the “Earth” moves, this pattern continues.
Ask students the following questions, answers given at the end. This can be created as a quiz on a free online website which will give you feedback on individual student marks.
1) The celestial objects like the Sun, other stars, and planets appear to move in the sky. We see them rise and set…
A) From North to South
B) From South to North
C) From East to West
2) What is Earth’s spinning motion called?
3) What are the similarities between the Earth and a spinning top?
A) The top is rounded
B) The top spins on its axis
C) The top spins and stops
4) How does the Earth rotate about its axis?
A) The Earth rotates upright
B) The Earth rotates while tilted on its side
C) The Earth speeds up and slows down while spinning
5) How many degrees is the equator of the Earth tilted relative to ecliptic?
B) 23. 5º
6) Every place on Earth experiences 12 hours of day and 12 hours of night always.
7) What is the explanation of your answer above?
A) Each side of the Earth receives equal amount of light
B) The Sun shines on half of the globe always
C) The axis of the Earth is tilted so some places on Earth receives more than others and some less than others
8) The Philippines experiences almost exactly 12 hours of day and 12 hours of night.
9) What is the explanation of your answer above?
A) The Philippines is near the equator
B) The Philippines is near the North Pole
C) The Philippines is near the South Pole
10) Why do we see stars shine only at night?
Answers: 1C) 2B) 3C) 4B) 5A) 6B) 7C) 8A) 9)A) 10 The stars are still there in the day time but we cannot see them as the Sun is much closer so we see it as much brighter than the stars.
UK KS3 Physics — Space Physics: The Seasons
UK KS2: Year 5 Science — Earth and Space
UK KS1: Year 1 Science — Seasonal Changes
day and night
Earth, Other, The Sun
Small Indoor Setting (e.g. classroom)
6 — 12
Asking questions, Communicating information
Type of Learning
Modelling, Simulation focussed, Structured-inquiry learning
Sese, R., 2013, Why do we have Day and Night?, astroEDU, 1310, doi:10. 11588/astroedu.2013.1.81222
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Why do we have day and night?
- 20th Mar 2023
- Author: Michael Darch
What causes daytime and night-time?
To understand our day and night cycle we first have to talk about how our planet Earth spins in space on its axis. Our planet is always spinning in a counter-clockwise direction.
Earth is big! In fact its radius is 6,317 kilometres. Despite its size it only takes Earth 24 hours to complete a full spin and we call this a day.
The Sun radiates light out into space and some of that hits our planet Earth. As the Earth orbits or travels around the Sun, one side of the Earth is illuminated by its light.
But because the Earth is spinning, the side that is facing the Sun is constantly changing. The side of the Earth facing the Sun is lit up, that is our daytime! The other side, facing away from the Sun, is not lit up and is left in darkness. This is our night-time. And as the Earth spins we face towards then away from the Sun so we go from daytime to night-time and the cycle continues.
The Moon also spins on its axis – so it has day and night too! It takes 27.3 days to spins once about its axis so daytime lasts roughly two weeks followed by a fortnight of night-time. But because the Moon takes the same amount of time for it to spin once as it does to complete one orbit around the Earth, we always see one side of the Moon from Earth – the near side and it appears to go through phases. During phases like the crescent, quarter or gibbous moon we are looking at a bit of the daytime side of the Moon (the illuminated part) and a portion of the night-time side of the Moon (the dark region). Find out more about the phases of the Moon.
Why do hours of daylight change throughout the year?
The Earth isn’t just spinning on its axis once a day, it is also orbiting our star – the Sun as well. This orbit takes about 365 days, and we call it a year.
Earth is on a 23.4° axial tilt which means as Earth goes through its orbit around the Sun, one hemisphere is tilted closer to the Sun than the other. So when one hemisphere is closer it receives more sunlight for longer than the other hemisphere. The axial tilt is the reason we experience seasons on Earth.
Depending where you live on Earth, at certain times of the year you might experience 24-hour daylight and then 24-hour night-time! This happens at the highest latitudes (close to the poles) where for a few weeks of the year the Sun never rises or sets; it remains visible in the sky.
How does day and night affect life on Earth?
The fact we have a day and night cycle affects a lot on Earth. Diurnal creatures are animals that are active in Earth’s daytime while nocturnal animals are active in the night time. Not only that but you get animals who are active specifically at the in between, being active at times like dawn or dusk. We call these animals crepuscular.
Life on Earth has also adapted to the seasons as well. When the seasons change and the days shorten and get colder some animals have adapted to hibernate, where they enter a low energy state, and wait until the days get longer again. Other animals, like birds, often migrate to warmer climates when it gets cold.
What is day and night like on other planets?
Going beyond Earth you will find the day and nights of other planets in our Solar System to be very different from ours!
Jupiter has the shortest day even though it’s our largest planet, because it spins very quickly leaving it with a day of only 10.5 Earth hours long.
The longest day in our Solar System is Venus and its day is actually longer than its year! It takes longer to spin around once on its axis than it does to travel all the way around the Sun. A day on Venus is 243 Earth days long, while its year is only 225 Earth days. Another oddity Venus has is that it actually spins backwards compared to the other solar planets (except Uranus which spins on its side). This means that if you were living on Venus (and could see through the dense atmosphere) you would see the Sun rise in the west and set in the east – the opposite to what we experience on Earth.
Now Uranus is strange because it doesn’t rotate about its axis in an upright manner like a spinning top, instead it spins on its side like a bike wheel about its axle. The Earth’s axis isn’t perfectly upright, it’s tilted by 23.4 degrees whereas Uranus’ is on a tilt of 98 degrees! Theories suggest that both Venus’ and Uranus’ odd rotation is the result of huge planet-sized asteroids hitting these planets early in their formation leading to a substantial change in their axial tilt.
Imagine if life had developed on one of these planets. How different would it be to us because of a different duration and experience of day and night?
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Partsevskaya T.S. Abstract of the lesson in the preparatory group «Why day follows night»
Partsevskaya T.S. Summary of the lesson in the preparatory group “Why day follows night”
— Give the concept that the Earth has the shape of a ball, show the role of the Sun in the daily regime of living beings, their connection with the rotation of the Earth around its axis. To fix the concept of «day», «part of the day» (morning — afternoon — evening — night).
— Learn to establish temporary connections (successive change of parts of the day).
— Develop a desire to participate in a collective conversation, defend one’s point of view.
Methodical methods: Experiments, solving research and inventive problems, brainstorming, the game «Good — bad».
Material: Image of animals — a chipmunk, a bear, a picture of a flat and spherical earth, a globe, a silhouette of the Sun, a table lamp, a table.
Preliminary work: Lesson “We are the inhabitants of the Earth”, collective work on the art of the planet, the life of another planet, making collages, modeling, a complex lesson with viewing slides about space, pl. Earth, reading fiction.
— Encyclopedia “What is it? Who it?» parts 1, 3, 5, 7, 8 “Everything about everything”
— Atlas “The World of Man”
— “10 lessons in natural science” A. Gonchar
— “Everything about everything” (a fairy tale about a chipmunk and a bear)
— books “Why”, M. , 1992
— Guys, remember, recently in class we talked about our house. But not about the one in which you live with mom, dad, wooden, brick, but about our common house, where not only people live, but also trees: birches and aspens, crocodiles and fish and many other creatures. This? Our planet earth.
— What does our planet look like? (answers). And now listen to the story about what a dispute came out about this once between a chipmunk and a bear.
— Once upon a time there was a chipmunk, and he was not afraid of anyone. Once I met my friend a bear, we argued. And their dispute came out like this: who will be the first to see a ray of sunshine in the morning. So they climbed up the hillock and sat down. The bear sat facing in the direction where the sun should rise from behind the forest in the morning. And the chipmunk sat facing where the evening sun sets into the forest. They sat back to back. They sit and wait. A mountain rises in front of the chipmunk, and a flat valley in front of the bear (showing the layout and maps). And then it began to light up.
— Who do you think will be the first to see the sun? Why? Let’s wait, soon it will rise, and we will find out who won the argument.
— A bear sits and says: «Now the first ray will fall on the valley, and I will win the argument.» And there is no ray. The bear is waiting. Suddenly a chipmunk behind him screams: «I see, I see, I’m the first.» The bear was surprised: there was still a dark valley in front of him, and when he turned over his shoulder, he saw behind him…
— What did he see? (the first ray of light on top of the mountain).
— What surprised him so much?
— Why was the chipmunk happy?
— And now let’s see how the chipmunk won the argument.
EXPERIMENT #1: Here they are sitting and the sun is rising. It rises slowly, but neither the chipmunk nor the bear sees it yet. The sun is rising higher, and look what happened. Both of them are in the dark, and the first rays of the sun have already appeared on the top of the mountain.
— Where is the bear looking? (to where the sun should appear).
— And the chipmunk? (on mountain). Yes, he had already seen the rays of the sun for the first time.
— What prevented the bear from seeing the sun first? (convexity of the earth, roundness).
— So, guys, what shape does our planet Earth have? Yes, the shape of a ball.
— And once upon a time, when there were no cars, no planes, no houses, like ours, people thought that the sun could somehow rise and not rise, they did not know that the Earth was round and imagined it to be flat.
— What if the Earth were actually flat? Who would then win the argument? (children’s suggestions).
— Let’s check!
EXPERIMENT #2: Flat Earth. Lighting from under the table (table lamp) with animals sitting on the layout plane.
CONCLUSION: Yes, they would have seen it at the same time, and there would have been no winners.
— Here the sun has risen. The chipmunk and the bear rejoiced at the sun and dreamed: «If the sun did not set and it would always shine.»
— «And it will be good» — said the chipmunk.
— It will be good, warm in the forest … Children, help more, what will be good? It will be beautiful, elegant, fun from the sun. The dew will shine. How many berries will there be? Children, help them dream.
— It will be possible to swim, dry, splash, sunbathe … They dreamed, and the sun rose higher and higher, their mood began to change. The puddle near which the bear was sitting dried up, and he thought of the stream in which he liked to splash in the heat.
— What could he think? (shallows) He suddenly imagined that from the constant heat, his river, where he was fishing, could become shallow and even dry up. And I decided that the sun to always be is bad.
— What do you guys think. The sun will always be, is it good or bad? How?
— In the city, forest, there may be a fire, rivers dry up, the head may hurt. Yes, guys, when there is a lot of sun, it can be harmful.
— And how to sleep — held out the bear.
— The sun should shine, since everyone needs it, and it should not shine, since a lot of sun is also bad. How to be? Let’s think. (Answer options are to build awnings, use umbrellas, hats on your heads, a cloud will cover the sun…)
— That’s right, you need to make sure that the sun does not interfere. Guys, is it convenient to walk everywhere under an umbrella, sit under a canopy, sleep? This is a good idea, but in fact, we do not have to do any of this.
— Why? That’s right, as the evening comes, the sun itself leaves. Let’s remember the beginning of the lesson. The chipmunk and the bear were sitting and waiting for what? (when the sun rises). First, they saw a radiance in the place where the sun was supposed to rise. Do you know what this phenomenon is called? (dawn). (Show picture). With the dawn comes the morning, in the morning there is a shadow. Then the sun rises higher and higher above the earth and the day comes (picture display). Here is a mountain, and there is almost no shadow here. The sun has risen and continues its path, slowly begins to sink, the shadow from the mountain becomes longer and sharper, evening comes. And when the sun ends its journey, dusk sets in, and when it completely sets, night comes.
MORNING — EVENING — DAY — NIGHT — DAY OFF
— Do you want to see how it really happens?
EXPERIMENT No. 3: globe, animals, lamp.
— Earth — a ball, the Sun — a fireball. We know that the earth is round. And it is not the Sun that revolves around the Earth, but the Earth revolves around itself like a top and turns to the Sun in different directions. So the day replaces the night, and the night — the day (showing animals on the globe — illumination). Here the Earth turned around — a day passed. That’s how nature works.
— And who can say what night is? (I want to sleep, it’s dark).
— But didn’t the bear say that it’s «bad» when it’s always light, and night means «good»?
— Why is the night good? (the sun does not interfere with sleep, it is not hot, animals can hide from enemies, everyone is resting, people, animals, and plants are gaining strength in order to work well during the day).
— Is everyone good at night? For example, a chipmunk? The bear is big — he can scare. And the chipmunk? He can’t see in the dark, if a fox crawls into a hole, where to run?
— Who else has a hard time at night? (for people who work at night, it is harder, more energy is wasted, it is scary to go home at night, you will get lost in the forest at night, it is also scary …)
— But even a terrible night ends and morning comes, then everything becomes visible, everyone is heard.
— It is good for all living earthly beings that there is day and night, that day turns into night, and the night ends when the sun rises. And the chipmunk and the bear were no longer arguing, but each was busy with his own business.
PRODUCTIVE ACTIVITIES: Drawing in different ways parts of the day («day», «night»).
Why there is a change of day and night
01/29/2023 / Leave a comment / The world around us / By admin
Today we will analyze why there is a change of day and night on our planet.
Every day we watch how morning, afternoon, evening and night succeed each other. During the day we see the Sun in the sky, and at night we see the Moon and stars.
Sun is the closest star to our planet. Stars are incandescent, huge celestial bodies that radiate their own light. Moon is a satellite of the Earth.
The sun gives heat and light, without it there would be no life on our planet.
Our Earth revolves around the Sun. It makes one complete revolution around the Sun in a little more than 365 days (per year). We discussed in detail about the rotation of the Earth around the Sun in a separate article, read here.
In addition, our planet revolves around its own axis . An axis is an imaginary line that runs through the center of the earth.
Let’s do an experiment
Take a globe, find your city on it and mark it. Place a table lamp next to it, let it be our Sun. Now the lamp-Sun illuminates the city in which you live, and you have a day. And now we rotate the globe around its axis, and as soon as the city in which you live is on the other side of the lamp, there will be night.
Thus, as a result of the rotation of the Earth around its axis, morning, afternoon, evening, night pass, that is, day . In a day, as we know 24 hours .
Important!!! Night + morning + afternoon + evening = day. There are 24 hours in one day.
Important!!! The change of day and night occurs as a result of the rotation of the Earth around its axis. On the side that is turned to the Sun, there is day. On the opposite side, which is not illuminated by the Sun, at this time it is night.
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We have analyzed why there is a change of day and night on our planet.
We invite you to answer questions for self-examination:
- The sun is?
- Axle is this?
- What causes the change of day and night?
- Earth makes one revolution around its axis in …?
- Earth makes one complete revolution around the Sun in …?
1. Which celestial bodies emit their own light?
2. What axis does the Earth rotate around?
4. What does the Sun illuminate when it is night?