Redefining "Down"
Redefining Down is a Grade 5 science concept from Amplify Science (California) explaining how Earth's gravity changes the meaning of "down" depending on where you are on the planet. Because gravity always pulls toward Earth's center, a person at the North Pole and a person at the South Pole are both pulled straight down — yet they are standing feet-to-feet relative to each other in space. Covered in Chapter 2, this concept challenges students to think beyond fixed directions and understand gravity as a force always pointing inward to Earth's core.
Key Concepts
Because gravity always pulls to the center, the direction "down" is not the same for everyone in space. "Down" simply means toward the ground beneath your feet.
For a person at the North Pole, down is toward the center. For a person at the South Pole, down is also toward the center. This means that relative to space, people on opposite sides of the world are standing feet to feet!
Common Questions
What direction is down on Earth?
Down always means toward the center of Earth, wherever you are standing. For someone at the North Pole, down points toward Earth's core in one direction; for someone at the South Pole, down also points toward the core, but in the opposite direction relative to space.
How does gravity define the direction of down?
Gravity pulls all objects toward the center of Earth, so down is defined by where gravity pulls you — always straight toward the planet's center. This means people on opposite sides of the globe both experience down as toward the ground beneath their feet, even though they point in opposite directions in space.
Would someone at the South Pole fall off Earth?
No. Gravity keeps people on Earth's surface no matter where they are. A person at the South Pole feels down as toward Earth's center, just like anyone else. Gravity holds them to the surface even though from space it looks like they are upside down compared to someone at the North Pole.
Why do people on opposite sides of Earth not fall off?
Earth's gravity pulls equally in all directions toward its center. People on the opposite side of the world are held to the surface by the same gravitational force pulling them inward toward the core. There is no wrong side of a sphere when gravity acts from the center.
When do 5th graders learn about gravity and direction?
This concept is covered in 5th grade science. Amplify Science California Grade 5 Chapter 2 challenges students to reconsider what direction means in space while studying Earth's rotation and gravity.
How is down different in space compared to on Earth?
On Earth, down is always toward the planet's center due to gravity. In deep space far from any massive object, there is no preferred direction — astronauts experience weightlessness because there is no large gravitational force pulling them in any direction.
Which textbook covers the concept of down and gravity for 5th grade?
Amplify Science (California) Grade 5 introduces this concept in Chapter 2, using the idea of gravity pulling toward Earth's center to challenge students' assumptions about up and down.