Nebular Hypothesis and Planetary Formation

Flashcards covering the Nebular Hypothesis, the formation of the Solar System, key historical proponents, and the developmental stages and internal layers of the Earth.

Nebular Hypothesis

The theory that the Sun and all the planets of the Solar System began as a giant cloud of molecular gas and dust.

Solar Nebula

A giant cloud made mostly of hydrogen and helium, with small amounts of heavier elements, that eventually formed the Solar System.

Protoplanetary Disk

A flattened disk formed from the solar nebula as it collapsed inward due to gravity and increased its rotation.

Proto-Sun (Protostar)

The central part of the protoplanetary disk where most of the material collected before becoming a sun.

Nuclear Fusion

The process triggered by increasing pressure and temperature in the proto-Sun where hydrogen atoms combined to form helium.

Accretion

The process where dust and gas particles in the disk collided and stuck together to form larger objects.

Planetesimals

Larger objects formed via accretion that continued to grow into protoplanets and eventually became planets.

Terrestrial Planets

The group of relatively small, dense, and rocky planets formed in the high-temperature inner Solar System, including Mercury, Venus, Earth, and Mars.

Gas and Ice Giant Planets

Large planets composed mainly of hydrogen, helium, and icy compounds formed in the lower-temperature outer Solar System, including Jupiter, Saturn, Uranus, and Neptune.

Solar Wind

Strong winds from the Sun that pushed away remaining gas and dust from the inner Solar System during the final stage of formation.

Emanuel Swedenborg

The scientist who, in $1734$, first suggested that the Solar System formed from a cloud of matter.

Immanuel Kant

The philosopher who proposed in $1755$ that gravity caused the rotating cloud to collapse and form the Sun and planets.

Pierre-Simon Laplace

The scientist who expanded the Nebular Hypothesis in $1796$ by explaining that the rotating cloud flattened into a disk.

Victor Safronov

The scientist who developed the modern Solar Nebular Disk Model (SNDM) in $1972$, explaining planetary formation through accretion.

Proto-Earth

The early phase of Earth, which was extremely hot and likely consisted almost entirely of melted magma.

Planetary Differentiation

The process where Earth's materials separated according to density, with heavier metals sinking to the center and lighter rocky materials rising to the surface.

Core

The innermost layer of the Earth, made mostly of iron and nickel, which plays an important role in producing Earth's magnetic field.

Mantle

The thick layer between the core and the crust made mostly of silicate rocks containing iron and magnesium.

Crust

The thin, outermost layer of the Earth that formed when magma from the mantle rose to the surface, cooled, and hardened.

Magma

The molten rock produced when heat inside the mantle causes some rocks to partially melt.