Viisaus Science Theory
Topic: Earth and Space
12/3/2025
Objective
• 7ESs.01 Describe how planets form from dust and gas, which are
pulled together by gravity.
• 7ESs.02 Know that gravity is the force that holds components of the
Solar System in orbit around the Sun.
• 7ESs.03 Describe tidal forces on Earth as a consequence of the
gravitational attraction between the Earth, Moon and Sun.
• 7ESs.04 Explain how solar and lunar eclipses happen.
Solar system
Solar system
• All planets follow a path or orbit in the same direction
around the Sun
• Most of the moons of the planets orbit their planets in
the same direction as the planets rotate around the
Sun
• All the planets orbit the Sun in the same plane. Orbits
that are in the same plane could all placed on the
same flat surface, means Solar System looks flat
Formation of stars
• Stars formed from clouds of dust
and gas called nebula
• Some young stars can also be
seen with a flat disc of dust
around them
Formation of planets and stars
• All particle of dust and gas have their own weak gravity. The particles
was pulled to each other due to their own gravity
• As they stick together, their total mass increases, does the strength
of their gravity
• This starts to form a small ball which gradually gets bigger
• If the ball gets beyond a certain size, it will get hot enough to
become star. If not, it will become a planet
Formation of planets and stars
Early stage of star formation
Movement in space
• Since the Sun has largest mass (330 000 times greater than Earth) in
the Solar System, then it has largest gravity.
• The strength of gravity in Earth is 10 N/kg meanwhile on the Sun is it
270 N/kg. The Sun gravity gets weaker as the distance from the Sun
increases.
• The gravity of Sun holds all the planets in their orbits.
Movement in space
• The orbits of the planets including
Earth almost circular
• The force of gravity from the Sun that
acts on a planet always acts towards
the Sun. If not, the planet in a straight
line into space
• Mercury is the closest to the Sun
which has the strongest pull from the
Sun’s gravity. This cause mercury
orbit with the highest speed
Movement in space
• Air resistance is one of those forces caused by moving object having to
push against the particles in the air which acts in the opposite direction
to the movement. The faster the object, the greater the air resistance.
• No air in the space. There are very few particles in the space. A space
where no particles called vacuum. The Earth and planets also moving in
a vacuum. The only force acting on the planets is from gravity.
Tides
• The change in depth of the water called tide. The different in depth
between high and low tides is tidal range. Earth tides cause the land to
change in height.
Project (GC: hydwmq2)
• Watch the video.
• Explain tidal force, high tide and low tide in details (within 50
words).
• Answer these questions:
a) what the time between one high tide and next high tide.
b) what the time between one low tide and next low tide.
c) what the time between a high tide and next low tide.
• Due date: 14/2/2025 (FRI)@1500