Solar Nebula Forms
A concentration of hydrogen
gas and dust swirling around
our young Sun.
Formation of Earth's Early
Atmosphere and Oceans
Volcanos spewed gases —
including water vapor — into
the atmosphere. When
things cooled down enough
the water vapor condensed
as liquid water in our oceans.
Solar System Cleaned Up
“Leftovers” in the solar
nebula are blown into the
outer solar system when
nuclear fusion gets going in
our Sun.
First Stable Continental
Crust
In other words, things were
calming down on Earth and
stable land was forming.
Gas Giants Form
Jupiter, Saturn, Uranus, and
Neptune form in the cooler,
outer solar system
Impacts Events Dramatically
Reduced in Number
Asteroids continue to strike
Earth and the other planets,
but not as frequently
Pluto Forms
Pluto, our ninth planet, is
considered by some to be
more related to the objects
in the Kuiper belt, a band of
rocky icy bodies that lie b
.eyond Neptune's orbit.
Formation of Dirty
Snowballs in Space . . .
Comets
Initial Crust on Earth
Early Earth was HOT.
Eventually the molten outer
layers cooled, forming a
crust. This crust was probably
a bit like our ocean crust
today.
0Formation of Earth's Moon
Earth was hit by a Mars-sized
planet. Debris blown into
space around Earth
eventually coalesced and
formed our Moon
Mercury Chills Out
This small planet became
geologically inactive
Planetesimals Form
Baby planets less than a few
kilometers across form.
Terrestrial Planets Form
Mercury, Venus, Earth, and
Mars form in the hot inner
solar system.
Formation of Rocks in
Space . . . Asteroids
Planetesimals Grow Up to
Form Protoplanets
Planetesimals are large
enough to attract material
through gravity