Earth's Place in the Universe Summative 1 Review

Accretion

The process by which small objects such as dust gather together to make larger objects such as chondurals, Meteors, Asteroids, and then eventually planets.

Explain accretion using examples from the accretion lab, notes, and video.

by conducting experiments on the International Space Station. One experiment was combining salt, sugar, and coffee grounds in a bag and observing accretion taking place. They noticed that through electromagnetic force, the particles started to clump together and create larger pieces. We demonstrated this with the lab using water to show the accretion through collisions and then using a paper clip to demonstrated how gravity can pull the objects together and then they would collide.

Protostar

A contracting cloud of gas and dust; the earliest stage of a star's life

Nebula

A large cloud of dust and gas in space

Protoplanetary Disk

A rotating circumstellar disk of dense gas and dust surrounding a young newly formed star

At what point does the protosun become a star?

About 4.5 billion years ago, the mass reached a critical point, and the hydrogen at the center was under so much pressure that it fused with another hydrogen atom, creating helium. This fusion was the birth of our star, the sun.

What do the largest clumps surrounding the protosun begin to form?

As a proto-star grows in size, the gases in the nebula from which it is born form a disk and spiral more and more quickly around its center. Eventually, elements on the fringe of the disk begin to form into globules with compositions that depend on their distance from the center. At smaller distances, where temperatures are higher, they are formed of heavy elements, while at greater distances they are formed of ices of water, methane and ammonia. These globules collide with each other and stick together to form larger, spherical bodies in a process called accretion. The larger bodies, with diameters of a few kilometers, are called planetesimals.

As the nebula begins to shrink and spin, what else does it begin to do?

As gravity does with everything, it began to condense the gas into varying regions of density. The denser regions began to grow into clumps of matter, which, over the course of time, would be the seeds for the formation of our sun, planets, and moons. From this collapse, pockets of dust and gas began to collect into denser regions. As the denser regions pulled in more and more matter, conservation of momentum caused it to begin rotating, while increasing pressure caused it to heat up. Most of the material ended up in a ball at the center while the rest of the matter flattened out into disk that circled around it. While the ball at the center formed the Sun, the rest of the material would form into the protoplanetary disc.

Conservation of Angular Momentum

As the spinning cloud contracts, it begins to spin faster ensures that protostars rotate rapidly and are surrounded by spinning disks of gas

How can dust become rock? Explain.

Dust through accretion adds other dust to itself. It then though Electromagnetic Force bonds together to form Chondrules. Then as accretion continues it builds to Meteoroids and so on. As soon as it becomes a chondrule it will be considered rock.

What force causes the gas cloud (also called a nebula) to begin to contract?

It's believed that before our solar system was formed 4.6 billion years ago, a nebula, which is an interstellar cloud of gas and dust, was present in our location. Then, about 4.57 billion years ago, something happened that caused the cloud to collapse. This could have been the result of a passing star, or shock waves from a supernova, but the end result was a gravitational collapse at the center of the cloud.

What evidence do scientists have to back the theory?

Large bodies in the Solar System have orderly motions. There are three types of planets. small, rocky terrestrial planets large, hydrogen-rich Jovian planets tiny, rocky/icy Dwarf planets (tends to be irregular) Asteroids & comets exist in certain regions of the Solar System We can observe stars forming in interstellar clouds of gas. The Orion Nebula shown has newborn solar systems in it.

As the newly formed planets begin to cool, what do the smaller clumps begin to form?

Once planetesimals form, collisions continue, but they tend to be destructive, and only the largest planetesimals survive. These continue to grow by assimilating surrounding material, including smaller planetesimals, to become planets. The composition of planets closer to the center of the system differs from that of those farther away. The planets within a critical distance, where temperatures are warmer, are rocky, while those beyond the critical distance have solid cores and thick, gaseous atmospheres. At the fringes of the solar system, where gravitational forces are weak, planetesimals never coalesce into planets. These icy bodies sometimes wander in eccentric orbits, and when they get close to the sun, we know them as comets.

As the newly formed planets begin to cool, what do the smaller clumps begin to form?

Planetesimals, which were early planets, began to grow in size from the clumps of matter and slam into each other as they revolved around the early forming sun. The theory of how our moon was formed lines up with this. It's believed that during the early formation of our solar system, a young Earth and an object about the size of Mars collided, sending debris into space and reforming within Earth's gravity and forming the moon.

What is the difference between a Chondrule, Meteoroids, and Asteroids?

Size is the main difference between the three. Chondrule smallest, then Meteoroids, and then. Asteroids. Also how they are made is different Electromagnetic Force bonds together to form Chondrules and meteoroids. Gravity creates Asteroids. Location is also different. Chondrules and meteoroids can be anywhere and most asteroids are in the asteroid belt.

What begins to take shape in the center?

The center of the disk of spinning gas experienced the least amount of centripetal force, which allowed a majority of mass from the nebula cloud to be attracted to the center by the force of gravity. In fact, 99.85% of all the mass in the solar system is in the sun. As gravity compacted the material in the sun, mostly hydrogen gas, pressure began to increase and heat the gas. About 4.5 billion years ago, the mass reached a critical point, and the hydrogen at the center was under so much pressure that it fused with another hydrogen atom, creating helium. This fusion was the birth of our star, the sun.

Chondrule

The mm to cm- sized spheres composed of dust that first solidified from the solar nebula

The Solar Nebular Theory

The solar nebular hypothesis describes the formation of our solar system from a nebula cloud made from a collection of dust and gas. It is believed that the sun, planets, moons, and asteroids were formed around the same time around 4.5 billion years ago from a nebula.

Explain what force causes these small dust particles to come together?

You have Electromagnetic Force for Chondrule, Meteoroids. And Gravity for anything bigger than a mountain or most asteroids.

Asteroids

rocky metallic objects that orbit the sun but are too small to be considered planets

Meteoroids

small rocky particle that moves through space, very small, friction can make meteoroid and air around it how enough to glow, burn in atmosphere