How did scientists discover the layers above us?

Scientists have always been curious about the atmosphere above us. But in the past, they could not just hop on a spaceship to see what was up there.

Instead, scientists hiked up mountains and rode hot air balloons to collect information at different altitudes. Over time, they noticed that the atmosphere had layers.

By the early 1900s, scientists had named layers of the atmosphere based on how the temperature changed at different heights above the sea.

Thanks to these studies, we now know there are five layers of the atmosphere. They are the troposphere, stratosphere, mesosphere, thermosphere and exosphere. Together, these layers protect us from the sun's harmful radiation.