Problem 17 Why do all planets orbit the Sun... [FREE SOLUTION]

Chapter 1: Problem 17

Why do all planets orbit the Sun in roughly the same plane? (E)

Short Answer

Expert verified

All planets orbit the Sun in roughly the same plane because they formed from the protoplanetary disk, a flat, spinning structure that resulted from the conservation of angular momentum during the collapse of the Solar Nebula. The planets inherited their orbital plane from the disk, ensuring that they all orbit the Sun in approximately the same plane.

Step by step solution

1. Formation of the Solar System

The Solar System was formed around 4.6 billion years ago from a giant cloud of gas and dust called the Solar Nebula. The process of formation began with the Nebula collapsing under its own gravity. As the cloud collapsed, it started to spin due to the conservation of angular momentum.

2. Disk-shaped structure

As the cloud continued to collapse and spin, its spinning motion caused the cloud to flatten into a disk-shaped structure called the protoplanetary disk, with the Sun forming at the center. This disk-shaped structure is a result of the conservation of angular momentum and the balance of forces acting on the particles in the cloud. In this flattened structure, both gravitational force and centripetal force play a crucial role.

3. Conservation of angular momentum

Angular momentum is a measure of the motion of an object that is rotating around a specific axis. In the case of the Solar System, the angular momentum was conserved as the cloud of gas and dust collapsed. Due to this conservation, the spinning motion of the cloud became faster, and the particles in the cloud remained in roughly the same plane as they orbited the center (where the Sun would eventually form).

4. Formation of planets

Within the protoplanetary disk, small solid particles started to collide and stick together, forming larger clumps. Over time, these clumps grew in size, accumulating more and more material, eventually forming the planets that we see today. Since the planets formed within the protoplanetary disk, they inherited the same orbital plane, which explains why their orbits are roughly in the same plane around the Sun.

5. Conclusion

The orbits of all planets in the Solar System lie roughly in the same plane because they formed from the protoplanetary disk, which was a flat, spinning structure. This flat structure was a result of the conservation of angular momentum during the collapse of the Solar Nebula. The planets inherited their orbital plane from the disk, which ensures that they all orbit the Sun in approximately the same plane.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Protoplanetary Disk

The protoplanetary disk is a key element in the formation of our Solar System. It began as a large, rotating cloud of gas and dust, known as the Solar Nebula. When this cloud collapsed under its own gravity, it didn't just contract into a ball.
Instead, due to the rotational motion, it formed a flattened disk-shaped structure. This is known as the protoplanetary disk. The conservation of angular momentum ensured that as the nebula contracted, it spun faster and flattened into a disk.

The Sun formed at the center of this disk.
Particles within the disk moved around the center, much like skaters around an ice rink.
The swirling motion of the disk was crucial for planetary formation.

The protoplanetary disk's flat shape is critical in explaining why the planets orbit the Sun in nearly the same plane today.

Angular Momentum

Angular momentum is a property of rotating systems, like our solar nebula. It is a measure of an object's tendency to continue rotating around a central point or axis. As the nebula collapsed to form the Solar System, it spun faster, similarly to how a figure skater spins faster when they pull their arms in.
This momentum is conserved, meaning the total angular momentum of the system remains unchanged unless acted upon by external forces. For the Solar System:

The original nebula was vast and moved slowly.
As it collapsed, the conservation of angular momentum caused it to spin faster and flatten.
This process helped organize the material into a thin, rotating disk.

The preservation of angular momentum is why the planets formed in a disk and continue to orbit in a relatively flat plane.

Planetary Orbits

The nearly circular paths the planets follow around the Sun are called orbits. These orbits lie mostly within the same flat plane, a direct inheritance from the protoplanetary disk. As small grains within the disk began to collide and coalesce, they formed larger bodies鈥攑lanetesimals.
These planetesimals then attracted more material, eventually growing into planets. This process occurred within the constraints of the protoplanetary disk, meaning:

Planets formed from the same disk of materials.
This disk was flattened due to angular momentum conservation.
Planets, therefore, inherited a shared orbital plane.

Understanding planetary orbits and how they came to be in alignment enhances our comprehension of both our Solar System and other star systems beyond.

91影视

Why do all planets orbit the Sun in roughly the same plane? (E)

Short Answer

Step by step solution

1. Formation of the Solar System

2. Disk-shaped structure

3. Conservation of angular momentum

4. Formation of planets

5. Conclusion

Key Concepts

Protoplanetary Disk

Angular Momentum

Planetary Orbits

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