A satellite is anything that orbits a planet or a star, like Earth, the moon, or the sun. Humans use satellites to take measurements and pictures that help us understand more about our planet.

This animation shows the radar pulse from the Sentinel-6 Michael Freilich satellite's altimeter bouncing off the sea surface in order to measure the height of the ocean. Credit: NASA/JPL-Caltech
This animation shows the radar pulse from the Sentinel-6 Michael Freilich satellite’s altimeter bouncing off the sea surface in order to measure the height of the ocean. Credit: NASA/JPL-Caltech

To collect data about the ocean, satellites use measurements called altimetry.

These altimeters work a bit like a bat using echolocation! The satellite sends a radar or laser pulse toward the ocean surface and waits for them to bounce back.

A close-up of a bat in flight with its wings fully extended against a warm, blurred background.

By timing how long it takes for these pulses to return, the satellite calculates the distance to the ocean.

To make sure the data is accurate, we use lots of satellites in space, combined with boats and instruments on the surface of the ocean to measure how the ocean changes over time.

A satellite orbiting above Earth with the planet's surface and atmosphere visible in the background.

THINK-PAIR-SHARE

What other types of data would we need to track how the ocean is changing?