How did Earth form?

Collapsing Interstellar Clouds Stars and planets

form from clouds of gas and dust, called interstellar clouds

Consist of gas: Hydrogen and Helium

Usually low density, can condense due to gravity and form a star or a planet.

At first the collapse is slow, but it accelerates and the cloud soon becomes much denser at its center.

It will spin faster and faster as it contracts (ice skater pull arms to body to spin faster)

Eventually slows and cloud becomes flattened, becoming a rotating disk.

Sun and Planet Formation

The disk of dust and gas that formed the Sun and planets is known as the solar nebula.

Dense concentration at center became the Sun.

Temperature differed, Hotter at center and cooler at edges of disk

Due to temp differences different compounds were able to condense depending on distance from Sun

Condensed material accumulated to from larger bodies.

Planetismals – Space object built of solid particles that can form planets through collisions and merges

Overall result was the planets

Early Planets

Jupiter formed first, using much of the material around it

This is why Jupiter is the largest Planet

The sun took most of the gas from the inner planets

This is why they are solid with few moons

Debris

Most collided into planets or was sent out of the solar system.

The remnants remain in the asteroid belt between Jupiter and Mars.

Jupiter's gravitational force prevents them from forming into a planet.

Asteroids

Rocky remnants of the early solar systemMost are less than 1 km in diameter, move

slowly

C – Type (Carbon) S – Type (Silica) M - Type (Iron-Nickel)

Asteroid Belt (Between Mars and Jupiter)

Meteoroid – asteroid that begins to fall towards Earth

Meteor – Meteoroid that begins to burn up in Earth’s atmosphere

Meteorite – A meteor that does not complete burn up in atmosphere and strikes Earth’s surface

Less than 100 m in diameterMove at fast speeds

Comets

Small bodies of rock and ice that have highly eccentric orbits

Periodic Comets – repeatedly return to inner solar system Halley’s Comet (76 Years, last seen

1985) Kuiper Belt – Located Beyond Neptune

Come very close to Pluto in Aphelion, near sun at Perihelion

Parts of a Comet

Coma Extended volume

of glowing gas Nucleus

Small solid core of the comet

Tail

Comet tails ALWAYS point away from sun When come within 3 AU of the sun begin to

evaporate Gas and dust pushed away by radiation from

sun Meteor Shower – Earth intersects cometary

orbit. Particles burn up in atmosphere