Topic 3.1 - Our Solar System

Solar System

All objects caught in the gravitational field of a star, revolving in orbital paths.

Nebular Hypothesis

Gravity pulled matter and gases together to form our Sun and planets 4.6 billion years ago.

Accretion

The process of gravity coalescing matter into celestial objects.

Chemical Fractionation

Heavier elements sink to Earth's center while lighter elements rise to form the crust.

Moon Formation Theory

A Mars-sized object crashed into young Earth, throwing debris that formed the Moon.

Inner Planets

Made of rock and metal with solid surfaces; smaller and denser.

Outer Planets

Made mostly of gases with thick atmospheres; larger with ring systems.

IAU Planet Requirements

Must orbit the sun, be mostly spherical, and clear its orbit of debris.

Dwarf Planet

Orbits the sun and is nearly round, but has not cleared its orbit of debris.

Kuiper Belt

A region of icy leftover objects located beyond the orbit of Neptune.

Comets

Small bodies of ice, rock, and dust that develop a vaporized tail near the sun.

Meteor

A meteoroid that enters Earth's atmosphere, producing a streak of light.

Oort Cloud

Immense, theoretical sphere of icy debris that surrounds our solar system.

Asteroids

Rocky objects revolving around the sun that are too small and numerous to be considered planets

Meteoroid

a small, metallic, rocky object that moves through space

First zone

Inner rocky planets which are made of rocks and metal, Mercury, Venus, Earth, Mars (Smaller and hotter)

Second Zone

Outer planets which are made of gas, Jupiter, Saturn, Uranus, Neptune (Larger and cooler)

Third Zone

The Kuiper belt, a distant, region beyond Neptune that is made up of icy bodies, rocks, and dwarf planets (Ex: Pluto)

Molecular Cloud

Dense, massive cloud of gas and dust where molecules can form and exist

Solar Nebula

Massive, rotating cloud of interstellar gas and dust that collapsed by a shockwave that caused it's gravity to overpower, to create our solar system

Protoplanetary disk

A massive, rotating, pancake-like cloud made of 99% gas and 1% solid dust (ice, carbon) where planets, asteroids, and comets are built.

How does a protoplanetary disk form?

A part of a giant molecular cloud becomes unstable (usually from a passive shockwave of a supernova) and pulls the material inward to form a protostar.

Why do protoplanetary disks spin?

Gravity pulls the cloud's gas inward, this causes it to shrink in size. As soon as it shrinks and has any slight rotation then it will build angular momentum and spin faster.

Why do protoplanetary disks appear flat?

Vertical Collapse, material falls straight to the center from the rotational poles (top and bottom of the surface) due to the gravity.

Rotational poles

Two points on the surface of a spinning object where the axis sticks out. (EX: North pole, South pole)

What is CentriFUGAL force?

Outward force. In this scenario it would be the force pulling away from the sun because of the fast forward motion of revolution

CentriPETAL force

Pulls inward. Inward force. In this scenario it would be the force pulling into the sun because of the sun's gravitational pull.

Planetesimal

A solid rock in space that has enough size for it's gravity to start influencing the space around it. (Asteroids, comets)

Tidal lock

When an object in space takes the same amount of time to rotate and revolution (ex: our moon)