Gravity & Orbit
Draw a simple model showing a planet orbiting a star. Label the planet, star, and the force keeping the planet in orbit.
Gravity pulls the planet toward the star, keeping it in orbit.
Draw a model showing the relative sizes of the Sun, Earth, and Moon.
The Sun is the largest, Earth is medium, and the Moon is the smallest.
What is a solar eclipse?
A solar eclipse happens when the Moon moves between the Earth and the Sun, blocking the Sun's light.
What is the Big Bang Theory?
The Big Bang Theory is the idea that the universe started as a small, hot, and dense point about 13.8 billion years ago and has been expanding ever since.
Sketch a model comparing the orbits of an inner planet and an outer planet. Which moves faster? Explain how gravity causes this difference.
Inner planets move faster because the star's gravity is stronger the closer a planet is.
Two planets are the same distance from a star, but Planet X has twice the mass of Planet Y. Draw a model of their orbits and explain which planet experiences a stronger gravitational pull.
Planet X feels a stronger pull because gravity increases with mass.
What is a lunar eclipse?
A lunar eclipse happens when the Earth moves between the Sun and the Moon, causing Earth’s shadow to cover the Moon.
According to the Big Bang Theory, what was the universe like before it began expanding?
The universe was a tiny, hot, and dense point containing all the matter and energy.
Create a model showing how the Sun’s gravity affects a comet’s path. Use evidence to explain why the comet’s speed changes as it gets closer to the Sun.
The comet moves faster as it gets closer because the Sun’s gravity pulls it in more strongly.
Draw two objects in space: one with a small mass and one with a large mass. Add arrows to show the gravitational force between them. Use scientific reasoning to explain how mass affects the strength of gravity.
The larger object has a stronger gravitational pull because gravity increases with mass.
Use three objects from the basket to model a solar eclipse. Explain the position of the Sun, Moon, and Earth.
The Sun is the largest object, the Moon is in the middle, and the Earth is behind the Moon. The Moon casts a shadow on Earth.
What happened immediately after the Big Bang?
The universe started expanding rapidly, and particles began forming as it cooled.
Two planets have the same mass, but one is twice as far from the Sun as the other. Draw their orbits and explain which planet experiences a stronger gravitational pull.
The closer planet feels a stronger pull because gravity weakens with distance.
Sketch a model showing how gravitational force changes as distance increases. Write a short argument explaining why gravity is stronger when objects are closer together.
Gravity weakens as distance increases because the force spreads out over space.
Why don’t we have a solar or lunar eclipse every month?
The Moon’s, the Sun, Earth, and Moon have to line up perfectly.
How does the Big Bang Theory explain the formation of galaxies and stars?
As the universe expanded and cooled, gravity pulled gas and dust together to form stars and galaxies over time.
Model how the force of gravity would change if the Sun's mass doubled. Use scientific reasoning to explain how this would affect the planets' orbits and their speeds.
If the Sun's mass doubled, gravity would be stronger, pulling planets into smaller, faster orbits.
Why do gas giants like Jupiter have so many moons compared to Earth?
Gas giants have stronger gravity due to their large mass, so they can capture more moons and hold them in orbit.
Model a lunar eclipse using objects and explain why the Moon looks red during a total lunar eclipse.
The Sun, Earth, and Moon form a straight line with Earth in the middle. The Moon looks red because Earth’s atmosphere bends some sunlight, allowing only red light to reach the Moon.
What does the Big Bang Theory suggest about the size of the universe when it first began?
It suggests the universe started as a single, extremely small and dense point, sometimes called a "singularity."