Modified & Updated: 23 Sep 2023

Northern Lights

The thermosphere is a fascinating layer of Earth’s atmosphere that holds many intriguing secrets. Situated between the mesosphere and the exosphere, this region is characterized by its high temperatures and incredibly low density. In this article, we will delve into the realm of the thermosphere and uncover ten captivating facts about this unique atmospheric layer.

Table of Contents

What is the Thermosphere?

The thermosphere, derived from the Greek words “thermos” meaning heat, and “sphaira” meaning sphere, is the layer of Earth’s atmosphere located approximately 80 kilometers (50 miles) above the planet’s surface. It is known for its extreme temperatures, which can soar up to a scorching 2,500 degrees Celsius (4,500 degrees Fahrenheit) during the day.

Atmospheric Composition

Primarily composed of nitrogen and oxygen molecules, the thermosphere also contains trace amounts of other gases such as helium, hydrogen, and carbon dioxide. However, due to the low density, the number of molecules per cubic meter is significantly lower compared to the lower atmospheric layers.

Temperature Variation

Despite its high temperatures, the thermosphere would not feel hot to us because the molecules in this layer are so far apart. The lack of molecular density means that there is a negligible transfer of heat energy to our bodies. In fact, if you were to stand in the thermosphere without any protective gear, you would feel extremely cold due to the absence of air molecules to conduct and retain heat.

Auroras in the Thermosphere

One of the most mesmerizing phenomena associated with the thermosphere is the aurora borealis (northern lights) and aurora australis (southern lights). These stunning light displays occur when charged particles from the Sun, such as electrons and protons, collide with atoms and molecules in the thermosphere. The collisions excite the particles, causing them to emit beautiful colors as they return to their original states.

Thermosphere Aurora Borealis
Image from Unsplash

The Ionosphere Connection

The thermosphere and the ionosphere are closely intertwined. The ionosphere is a region within the thermosphere where the high-energy radiation from the Sun ionizes the atoms and molecules, creating charged particles known as ions. The ionosphere plays a crucial role in radio communications as it reflects and refracts radio waves, enabling long-distance transmissions.

Space Shuttle Orbits

The International Space Station (ISS) and other satellites orbit the Earth within the thermosphere. The thin atmosphere in this layer exerts a small drag force on the spacecraft, causing their orbits to gradually decay over time. As a result, periodic adjustments are necessary to boost the spacecraft back to its desired orbit.

Thermosphere Expansion

The thermosphere expands and contracts in response to solar activity. During periods of high solar activity, the increased intensity of ultraviolet and X-ray radiation causes the thermosphere to expand and rise in altitude. Conversely, during periods of low solar activity, the thermosphere contracts and moves closer to Earth.

The Thermosphere and Space Weather

Space weather, which refers to the conditions in the space environment surrounding our planet, can significantly impact the thermosphere. Solar flares, coronal mass ejections, and geomagnetic storms can generate disturbances that affect the density, composition, and temperature of the thermosphere.

hurricane harvey Space Weather
Image from Pixabay

Satellites’ End of Life

When satellites reach the end of their operational lifespan, they are purposely directed to re-enter the Earth’s atmosphere through the thermosphere. The high temperatures and low density of this layer cause the satellites to burn up during re-entry, ensuring that they do not pose a threat to populated areas on the ground.

Thermosphere Exploration

Although the thermosphere presents numerous challenges for exploration, scientists have developed satellites and instruments to study this elusive layer. These tools enable us to collect data on the thermosphere’s composition, temperature, and other properties, contributing to our understanding of Earth’s atmosphere and its interactions with space.


The thermosphere, a hot and rarified layer of Earth’s atmosphere, holds a wealth of intriguing facts and phenomena. From its extreme temperatures to the ethereal auroras, this region captivates both scientists and curious minds alike. By exploring the thermosphere, we deepen our understanding of Earth’s atmospheric dynamics and the intricate connections between our planet and the vastness of space.

Frequently Asked Questions (FAQs) 

How thick is the thermosphere?

The thermosphere does not have a defined thickness like the troposphere or stratosphere. Instead, its boundaries transition gradually into the other atmospheric layers. However, its average altitude ranges from approximately 80 kilometers (50 miles) to 600 kilometers (370 miles) above the Earth’s surface.

Can humans survive in the thermosphere?

Surviving in the thermosphere without any form of protection would be impossible for humans due to the lack of air pressure and extreme temperatures. The absence of air molecules to breathe and the intense heat would make it inhospitable for life as we know it.

What causes the temperature increase in the thermosphere?

The high temperatures in the thermosphere are primarily caused by the absorption of extreme ultraviolet (EUV) radiation from the Sun. The energized particles in this layer reach such high temperatures because there are very few molecules to absorb and distribute the heat energy.

How does the thermosphere differ from the troposphere?

The thermosphere and troposphere are distinct atmospheric layers with different characteristics. While the thermosphere is located higher up and is known for its high temperatures and low density, the troposphere is the layer closest to the Earth’s surface and contains most of the planet’s weather systems.

Can the thermosphere affect satellite communications?

Yes, the thermosphere, particularly the ionosphere within it, plays a crucial role in long-distance radio communications. The ionized particles in the ionosphere can reflect and refract radio waves, allowing for long-range transmissions. However, disturbances in the ionosphere caused by space weather can affect satellite communications.