Earth in SpaceIn order to understand how our planet works, we need to

know where it came from and its place in the universe.

If we know how the Earth was first formed and how it has changed, how life developed over time, and how humans have

impacted the planet in the recent past, we can better understand how to respond to the environmental issues we face today and in

the future.

Where is theEarth located

in space?

https://futurism.com/videos/detailed-map-date-place-universehttps://www.vox.com/2014/9/4/6105631/map-galaxy-supercluster-laniakea-milky-way

Laniakea

https://futurism.com/videos/detailed-map-date-place-universe

Where is the Earth located in space?• Earth is a terrestrial planet, unique because it holds so much liquid water due to its

strong atmosphere. It is located in the “habitable zone” around its star, which means it is far enough away to be protected from the most dangerous solar radiation yet close enough to still receive adequate light and heat energy in order to support life. Earth formed about 4.5 billion years ago along with the rest of our solar system, soon after our sun formed.

• Earth has one moon that was probably formed by all the dust, rock, and debris leftover from an ancient planet that was destroyed when it collided with Earth soon after it was formed. (This is called the “Theia Impact hypothesis.”)

• Earth is one of four inner planets and eight total planets that orbit around its sun in a solar system, surrounded by a “belt” of asteroids and dwarf planets called the “Kuiper Belt” (including Pluto).

• Earth’s solar system is about 20 billion miles across, which is just a small fraction of a light year. The solar system is located about halfway along the inner rim of one of the spiraling arms of its galaxy – the “Milky Way” galaxy.

• The Milky Way galaxy is about 1000 light years across and is made of up to 400 billion stars and their solar systems. It is one of 30 different galaxies that are grouped together in the nearby region of the universe, called the “Local Group.”

• The Local Group where our galaxy is located is just one small part of a much larger section of the Universe called a “supercluster.” Until recently, scientists thought our supercluster contained about 2000 total galaxies that made up our “neighborhood” of the Universe. Just a few years ago, new technology allowed scientists to get a much better idea of how the Universe is organized, and we learned that we are actually part of a much larger supercluster, now called “Laniakea.”

• The Laniakea supercluster – made of about 100 thousand galaxies – is still just one small part of the larger Universe. The Universe is still expanding (maybe even faster now than ever before) and has no true center. However, scientists recognize that everything we are able to see and observe out in space is from the perspective of our tiny little spot in the Universe, so we often think of our galaxy as the center of everything – the center of the Universe.

• The newest technologies are allowing scientists to understand more about the Universe and its organization. This allows us to create new, 3D maps of everything we know so far that is out there in space. Everyday, our understanding of our place in space gets a little bit better.

Where is the Earth located in space?

How did the Earthget here? Where did

It come from?How has it changed?

Between 12 and 14 billion years ago, all of the matter and energy that exists in the Universe was concentrated in one single, tiny spot – we call this the “singularity.” Then, as the singularity became less and less stable, it eventually began to grow in size at a superfast speed (like a giant, sudden explosion). This “bang” released all the matter and energy shooting out into space, and is believed to be the beginning of the development of the Universe as we know it today.

https://www.brainpop.com/science/space/bigbang/

Evidence forthe Big Bang theory:

In the early 1900s, scientists developed a better understanding of how gravity works out in space. Along with new technologies that made observing planets and stars far away from Earth much easier and reliable, scientists combined their new understanding together as evidence to support the theory that the Universe began with a “singularity” and a sudden, explosion-like change. The main piece of evidence that supports this theory is the “Doppler effect.”

When scientists use specialized telescopes to look out into space, everything that is far away from our solar system gives off “red shift.” This means that everything that is not orbiting around our sun is getting further and further away. If everything in the Universe is moving further apart, we can assume that everything used to be closer together. Based on this idea, if you imagine going back in time far enough, everything used to be so close that it was all located together in the same spot – the “singularity.”

After the “Big Bang,” as all matter was zooming through space at superfast speeds, moving further and further apart, the force of gravity began to attract small particles – specs of dust and rock – together, forming larger and larger chunks of mass. The balance between these different forces led to a swirling motion (that we still commonly see out in space today). At the center of these giant swirls would always be a giant mass like a star or a black hole; each of these giant swirls is called a nebula. The remaining energy from the “Big Bang” kept everything in the nebula moving and swirling and the increasing pull of gravity from the giant mass at the nebula’s center started to organize all the chunks into larger bodies, like planets. Over billions of years, through cooling and collisions and more swirling, solar systems are formed. This process is called “accretion.”

https://www.youtube.com/watch?v=Uhy1fucSRQI

The Earth began to form about 4.5 billion years ago, soon after our sun and solar system started forming, through the process of “accretion.” It took another 1 billion years for the planet to cool enough to form land and oceans, and eventually very basic forms of living organisms. Another 1.5 billion years passed while life developed in the Earth’s oceans, and eventually produced enough oxygen in the atmosphere for living things to begin surviving and developing on land. About 540 million years ago (half a billion years ago), tons of new organisms developed and spread around the planet, including up out of the water and onto the land. About 250 million years later, dinosaurs began to dominate the planet, until they were killed by a giant

asteroid that crashed into the Earth about 66 million years ago. That’s when the mammals took over, spreading throughout the entire globe and every type of environment, and eventually leading the development of modern humans about 100 thousand years ago. Humans have only been on the Earth for about 0.0004% of its history, but we’ve certainly made a big impact in our short time. Welcome to the “Anthropocene” – “the age of humans.”

https://www.youtube.com/watch?v=gTsJubN68WE https://earthlymission.com/wp-content/uploads/2019/02/history_of_planet_earth.pnghttps://earthhow.com/earth-timeline-geological-history-events/ https://www.smithsonianmag.com/videos/category/science/what-is-the-anthropocene/cc

How does the Earth move in space? What is its relationship with

the sun and moon?

Earth’s orbit around the sun

The Earth’s orbit around the sun is elliptical, meaning it is oval- shaped rather than circular. This was discovered by a scientist named Kepler in the early 1600s. “Kepler’s laws of planetary motion” were one of the most important scientific discoveries ever made.

Earth’s motions around the sun• The Earth is held in its place in space by the force of gravity of our solar system’s star –

the sun. Earth’s motions are controlled by the balance between the remaining energy from the “Big Bang” and the force of gravity attracting all things to one another (especially BIG things, like the sun).

• The Earth’s orbit around the sun is not a perfect circle. It is elliptical (oval) due to the way gravity impacts bodies as they move through space. This means that the Earth is notalways the same distance from the sun throughout the year. (The closest point is called “perihelion” and the furthest point is called “aphelion.”) These differences in distance from the sun have nothing to do with the changes in Earth’s seasons.

• The Earth orbits around the sun (revolution) once every 365.25 days. The Earth is tilted on its axis which causes different parts of the planet to receive different amounts of direct sunlight throughout the year, causing the Earth’s seasons. (This is also why the Northern and Southern hemispheres experience opposite seasons at the same time.)

• The Earth also rotates on its axis once every 24 hours. As a region of the world rotates toward the sun, it experiences daytime, and then experiences nighttime as it rotates away again.

• Since different areas of the world experience daytime and nighttime at different times, the international community has created time zones aligned with lines of latitude and longitude. This is why the hours associated with daytime are the same everywhere.

Barycenter

The barycenter between the sun and Earth is actually insideof the sun. This is why the Earth feels the pull of the sun’s gravity so strongly. Because of how close the barycenter is, the sun controls the movements of the Earth and all the other planets. This is why the Earth has a very consistent orbit around the sun that rarely changes.

BarycenterA really important note

about barycenters:Planets don’t in fact orbit their

stars! They actually orbit the barycenter between them and their star. This is why so many planets throughout our solar system and the universe have strange orbits that work differently than Earth’s works. It also explains why so many planets undergo changes in their orbits much more frequently than Earth. Planets AND their stars are actually all orbiting the barycenter they share. But, because this point is often very close to or even inside of the star (due to huge difference in mass), it seems like the planets are orbiting around the star.

Earth’s 4 motions:

•Revolution – orbiting around the barycenter,

once every year (365.25 days)

•Rotation – turning on the axis,

once every 24 hours (1 day)

•Precession – “wobbling” axis changes direction,

once every 26,000 years

•Nutation – “rocking” axis slightly changes

angle of tilt, once every 18.6 years

Earth’s motions around the sun• Due to the fact that gravity has some special impacts on the way objects in motion

continue to move (like a planet on an orbit around a star), astronomical bodies move in many different ways. Earth’s movements are also influenced by the gravitational force of the moon as well. For this reason, in addition to revolution and rotation, the Earth also moves in two other less noticeable ways – precession and nutation.

• The Earth’s axis actually “wobbles” as it revolves around the sun, but so slowly that we can’t notice the difference. Since the axis of the Earth moves about one degree every 72 years, and makes a full cycle once every 26,000 years. This means that the Earth’s tilt changes over time. In fact, the planet is about half way through a cycle of this “axis wobble” right now. This changing in the tilt of the planet’s axis is called “precession.”

• The Earth’s axis also “rocks” or “sways” as it moves over time. This means that the planet’s axis actually increases and decreases by a slight amount about once every 18-19 years. This “rocking back and forth” of the Earth’s axis is called “nutation.”

• The moon also influences the way the Earth moves aroundits orbit. The moon revolves around the Earth on its angled,elliptical orbit once every 29 days, which is what causes thedifferent shapes (phases) of the moon throughout themonth. This also causes tides and the tidal “bulges.”

The Earth is actuallynot round…

Earth in Space• Earth’s location in space – our solar system, our galaxy, the entire Universe• The “Big Bang” theory• The nebular theory• How Earth has changed and developed over its 4.5 billion year history• Earth’s motions in space

• Barycenter and its connection to Earth’s motions• Revolution• Rotation• Precession• Nutation• Why each of these occurs and how long they each take• How do all these motions and forces impact the Earth?

• How the moon impacts the Earth