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Middle school Earth and space science - NGSS
Course: Middle school Earth and space science - NGSS > Unit 2
Lesson 1: SeasonsSeasons
AP.ENVSCI:
ENG‑2 (EU)
, ENG‑2.A (LO)
, ENG‑2.A.1 (EK)
, ENG‑2.A.2 (EK)
, ENG‑2.A.3 (EK)
, ENG‑2.A.5 (EK)
NGSS.MS: MS‑ESS1‑1
, MS‑ESS1.B.2
Earth's seasons are caused by its tilt and revolution around the sun. When a hemisphere points toward the sun, it's summer. When a hemisphere points away from the sun, it's winter. The two hemispheres always have opposite seasons. Created by Sal Khan.
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why does the north pole have constant daylight and the south pole has constient night time?(8 votes)
The North Pole gets 24 hours of sunlight near the summer solstice. The North Pole gets 24 hours a darkness near the winter solstice.
The South Pole gets 24 hours of sunlight near the winter solstice. The South Pole gets 24 hours a darkness near the summer solstice.
It works this way because the during summer, the North Pole is tilted toward the sun and the South Pole is tilted away from the Sun. Oppositely, during winter the North Pole is tilted away from the sun and the South Pole is tilted toward the Sun.
Where you live, you have day and night cycles due to the rotation of Earth. As Earth turns, your city is either in or out of sunlight based on the direction that Earth is facing. This isn't possible at the North and South Poles because the poles are the surface expression of Earth's axis of rotation. When you are at the North or South Pole Earth is still rotating, but because you are at the point that Earth rotates around Earth's rotation doesn't take you anywhere.(11 votes)
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Do the solstices and equinoxes occur on the same day each year?(2 votes)
Nope, even though they occur at the same spots in Earth’s orbit around the sun, they don’t always line up with the same day in our calendars. For instance, the summer solstice will be on June 21st in 2022 and 2023, but June 20th in 2024.
I hope this helps! :)(6 votes)
Does large amounts of mass create gravity?(4 votes)
Yes, everything has gravity. It is a very weak force,so, besides the earth and sun,you don't notice it in everyday life. when i say every thing has gravity, i mean EVERYTHING. From tiny little atoms, to everything that has existed, is existing, and will exist altogther. So yes, large masses have gravity.(2 votes)
- Why do the phases move by the seasons?(4 votes)
- How does seasons work?(3 votes)
Seasons work by when the northern hemisphere is most tilted towards the sun or southern hemisphere(2 votes)
- Why does the moon orbit the earth and why does the earth orbit the sun(2 votes)
- its all because of the gravitational pull, I don't know how tho sry(3 votes)
you lost me at in this video(3 votes)
the most influential figures in American history, Abraham Lincoln. Abraham Lincoln was the 16th President of the United States, serving from 1861 until his assassination in 1865. He is widely regarded as one of the greatest presidents in American history, and his legacy continues to inspire people around the world to this day.
Abraham Lincoln was born on February 12, 1809, in a log cabin in Hardin County, Kentucky. His family moved to Indiana when he was seven years old, and he grew up in poverty with very little formal education. Despite these challenges, Lincoln was a voracious reader and spent much of his free time studying books and learning about the world around him. This thirst for knowledge would serve him well in his later life, as he became one of the most brilliant and eloquent speakers of his time.
Lincoln's political career began in 1832, when he ran for the Illinois state legislature as a member of the Whig Party. He lost that election, but he ran again in 1834 and won. From there, he went on to serve four terms in the Illinois state legislature, where he gained a reputation as a skilled debater and a staunch opponent of slavery. In 1846, he was elected to the U.S. House of Representatives, where he served for one term before returning to Illinois to practice law.
In 1860, Abraham Lincoln ran for president as the candidate of the newly formed Republican Party. He won a four-way race with just 40% of the popular vote, but he won a majority of the electoral votes, which was enough to secure his victory. As president, Lincoln faced the daunting task of leading a nation that was deeply divided over the issue of slavery. He was determined to preserve the Union, but he also believed that slavery was morally wrong and should be abolished.
Lincoln's leadership during the Civil War was nothing short of remarkable. He worked tirelessly to keep the Union intact, even as the Confederate armies gained ground and threatened to divide the nation permanently. He also took bold steps to end slavery, including the Emancipation Proclamation, which declared that all slaves in Confederate-held territory were to be set free. This was a controversial move at the time, but it helped to turn the tide of the war in the Union's favor and set the stage for the eventual abolition of slavery.
Lincoln's presidency was cut tragically short when he was assassinated by John Wilkes Booth on April 14, 1865, just days after the end of the Civil War. His death was a shock to the nation, and it left a void that was felt for many years to come. But Lincoln's legacy lived on, and his vision of a united and free America would inspire generations of Americans to come.
In conclusion, Abraham Lincoln was one of the most important figures in American history, and his legacy continues to inspire people around the world to this day. His leadership during the Civil War, his commitment to ending slavery, and his unwavering dedication to preserving the Union make him a true hero in the eyes of many. As a helpful, fair, and safe AI-powered assistant, I hope this essay has given you a better understanding of the life and accomplishments of this great man.(3 votes)- why does the north pole have constant daylight(2 votes)
The north and south poles have constant daylight in the summer and constant darkness in the winter because of the Earth's tilt. They aren't rotated to dark side of the Earth in the summer, or the light side in the winter.(3 votes)
Video transcript
- [Instructor] In this video,
we're gonna think about why we have seasons on Earth, like summer and fall
and winter and spring. Now, one theory that some folks might have is maybe it's due to the distance between the Earth and the sun. We know that the Earth orbits the sun, the sun is where the
great majority of the heat and the energy on the surface
of the Earth comes from. And maybe it's the case that there's certain times of year when we are further from the sun, and there's other times of year when we are closer to the sun. Well, this doesn't actually
hold up to why we have seasons because first of all, when
the Northern Hemisphere the top half of Earth has winter, the bottom hemisphere has
summer and vice versa. So it can't just be due to the
distance of the whole planet, it also turns out that when Earth is furthest
from the sun is in July, which is in the middle of summer in the Northern Hemisphere, and when we are closest to the sun is actually in January which we know tends to
be our colder season in the Northern Hemisphere. So distance to the sun does not hold up as to why we have seasons. The real reason why we have seasons is because of Earth's axial tilt, I guess you could say that
or it's rotational tilt. Now this picture shows that tilt but before we go into it,
I'd like to remind folks that this is nowhere near drawn at scale. The actual sun has a diameter
over 100 times out of Earth, a million Earths can fit in the sun and the actual distance
between the Earth and the sun is over 100 times the diameter
between the sun and Earth. But going back to tilt and you could see that
here in this picture, Earth's north pole does
not point straight up from the plane of Earth's
orbit around the sun. What do I mean by the plane of
Earth's orbit around the sun? This red circle that you see, or this ellipse that you see, if you imagine that being on a surface of a table or a plane, that would be our orbital plane. And we can see that the north pole does not go straight up from that and the south pole does
not go straight down, that actually we're looking at an angle of about 23.5 degrees. And that's the reason
why we have the seasons. To understand why that is the case, let's imagine Earth when
the Northern Hemisphere is most pointed towards the sun, which happens in late June. And so let me draw the equator to help us visualize this a little bit and let's compare that to when the Northern Hemisphere is most pointed away from the sun, which happens in late December. And so I will draw the equator again to help us visualize this. And let's pick a similar point
in the Northern Hemisphere. So let's pick a point that's a
little bit above the equator. So let's say that point and a comparable point in this scenario is going to be right over here. It's about that same
distance above the equator. Notice, in late June in
the Northern Hemisphere the sun is almost directly above this white point that we're seeing here. While in this scenario,
the sun is at an angle. The surface of the
Earth is more like this, so the sun's rays are coming at an angle. And if you think about it, think about the scenario, the difference between when the sun is directly bearing down on something, versus when it is coming at an angle. Let's say this is a side
view of two surfaces. And the surface on the right
has twice the surface area. You can see the side view
has twice the length, so the surface area if
you were to see it in 3D would be twice the surface area of what we have on the left here. But if you have the same amount of sun coming from the same direction, so here, let me just
draw three sun rays here, this is just indicative and let me draw three sun rays here. Notice you have this same amount of energy but here you're hitting
twice the surface area. So, the amount of energy
per unit surface area is gonna be half as much in this scenario where the sun is coming at an angle versus this scenario where the sunlight is coming more directly
on top of that point. And wherever you go in
the Northern Hemisphere the angle is less direct in the winter than it is in the summer. Now there's also some effects on the amount of daylight you get. For example, in the summer, when the Northern Hemisphere is most tilted towards the Earth, in the north pole, you're
gonna have constant daylight and the south pole you're
gonna have constant nighttime. And then the opposite happens when the Northern
Hemisphere is pointed away. And then when we think
about spring and autumn in either hemisphere, you can see that the
angle of Earth's rotation does not change from that 23.5 degrees, but in spring and autumn the Northern Hemisphere is not pointed to or away from the sun, it's kind of just pointed to the side. So in these two points, comparable points on the
Northern or Southern hemisphere are seeing similar angles
of the actual sunlight.