Download a planet rotates on its own axis and revolves around

Solar System Formation and
MOTION
Process of Solar System Formation
Solar Nebula

The solar nebula is
the name of the
nebula that formed
into our own solar
system
Nebula

Gas and dust, very cold
Two forces at work

Gravity and pressure
balance each other out
to prevent nebula from
collapsing or falling
apart
Birth of a Star

The central part of the
solar nebula contained
so much mass and had
become so hot that
hydrogen fusion
began.

Outward pressure in
the center balanced
with the inward force of
gravity that the gas
stopped collapsing

Our sun was born!
Planets


Gas giants (Jupiter, Saturn, Uranus, and
Neptune) collected large amounts of dust in the
cooler, outer solar nebula
Closer to the sun, it was too hot for gases to
remain, so these inner planets are made of
rocky material (Mercury, Venus, Earth, Mars)
Planetary Motion
Everything in the solar
system moves according to
strict physical laws
 Each object follows different
time frames and patterns for
this to occur

Rotation


Rotation-Earth's
spinning on its
axis, which
happens every
24 hours or a
day.
This is how day
and night
happen
Revolution



Orbit – a planet rotates on its own
axis and revolves around the sun in
a path
Revolution- Earth completes an
orbit around the sun which
happens every 365.24 days or a
year (leap years would be 366
days)
This is how the seasons occur
How were planetary orbits
discovered?


Johannes Kepler, German astronomer
discovered this in 1601
Kepler's First Law of Motion

Planets do not move in a circle around the
sun, but in an elongated circle, or ellipse
Distances in space

Astronomical unit
(AU) – represents
the average
distance between
the Earth and the
sun

1AU
=149,597,817
km=92,955,807
mi
Kepler's Second Law

Kepler
discovered that
planets move
faster when
they are closer
to the sun and
slower when
they are further
away
Kepler's Third Law

If you know a planet's period of
revolution, you can calculate its
distance from the sun.
Law of universal gravitation


Developed by Newton, states that
the force of gravity depends on the
product of the masses of the
objects divided by the square of
the distance between them.
Gravity is always working in the
universe and it depends on the
objects size, mass and location