The importance of the mesosphere, the coldest part of Earth's atmosphere

A breakdown of Earth's atmospheric layers, including why it can get colder or hotter with altitude

Gases in the troposphere—the atmosphere's lowest layer—cool with increasing height as they get farther from the thermal energy emitted by Earth's warm surface. In the next layer—the stratosphere—ozone is increasingly heated by the sun's ultraviolet radiation with height. Because cooler air sinks and hotter air rises, the cooler troposphere and hotter stratosphere form a natural boundary keeping Earth's weather in the lowest layer.

A 101 on the science and history of meteor showers

Bits of rock, ice, and dust flying through space called meteors burn up in a spectacular display when they hit our atmosphere 60 miles up at an average of 30,000 mph. Some of these are isolated objects, but others are recurring phenomena caused by...

Why the edge of Earth's atmosphere varies depending on which property is considered

As the distance from Earth's center increases, the planet's gravitational force weakens, causing it to gradually lose its ability to retain gases at the farthest edge of its atmosphere—the exosphere. At a height of approximately 200,000 kilometers (124,000 miles)—halfway to the Moon—the exosphere has so little density that it is indistinguishable from interstellar space.

Shooting stars, or meteors, are fragments of asteroids and comets that burn up as they enter Earth's atmosphere, creating streaks in the sky called meteor showers.

Understanding why the thermosphere feels cold, despite exceeding 2,000 degrees Celsius

High-energy solar radiation can raise temperatures above 2,000 degrees Celsius (3,632 degrees Fahrenheit), but the air density in this layer is so low that there would be insufficient collisions between energized molecules and a person's skin to cause them to experience this warmth. Variations in the level of solar radiation reaching the layer cause it to swell and shrink.

View the transparency of Earth's atmosphere and how it blocks most forms of light

The gases that make up Earth's atmosphere block most harmful forms of electromagnetic radiation from reaching the planet's surface, except for some ultraviolet light. Their transparency to radio waves means this form of light can reach Earth's surface, which is why most radio telescopes are ground-based rather than space-based.

Breaking down the ionosphere, which reflects radio waves from Earth's surface

Made up of ionized regions within the mesosphere and thermosphere, the ionosphere contains charged particles produced when solar radiation knocks electrons free from atoms and molecules in the atmosphere. Before satellites, radio operators would bounce signals off these regions to wrap around the planet and extend the range of transmissions.

Explore Earth's atmosphere and what its layers contain in this interactive adventure

In this interactive, users can move from Earth's surface up through its atmosphere, exploring the natural phenomena found in each layer, including atmospheric rivers, auroras, and meteor showers. Artificial structures such as weather balloons and the International Space Station can also be found on the adventure.

Stars appear to twinkle because turbulence in the motion of molecules in Earth's atmosphere causes light to bend and wiggle rapidly on its way to the surface—a phenomenon called scintillation.

Stars appear to twinkle because turbulence in the motion of molecules in Earth's atmosphere causes light to bend and wiggle rapidly on its way to the surface—a phenomenon called scintillation.

Earth is constantly bombarded by material from space

Most of this matter is composed of small particles, with any smaller than 33 feet in diameter burning up in the atmosphere. Larger asteroids can reach the ground, and those larger than several thousand feet cause global damage, including earthquakes and tsunamis.

Atmospheric greenhouse gases trap thermal energy and make Earth habitable

The moon and Earth are at the same distance from the sun, but the moon experiences large fluctuations in surface temperature because it lacks an atmosphere to insulate it. Gases such as water vapor, ozone, carbon dioxide, and methane can intercept about 90% of the infrared radiation emitted by Earth's surface.

Why Earth's atmosphere constantly loses the universe's lightest elements to space

The masses of hydrogen and helium are too small for these gases to be held by Earth's gravitational force, particularly when these atoms are given energy from collisions with high-speed particles from the sun. Although the planet loses a meter-wide balloon's worth of hydrogen every second, it will still take billions of years to exhaust the planet of this element.

The boiling temperature of water decreases with increasing elevation because the molecules need less energy to overcome the lower atmospheric pressure associated with thinner air.

The sun and Earth's liquid outer core help create the northern and southern lights

Earth's magnetosphere, generated by the movement of molten iron deep within the planet, consists of a magnetic field that deflects charged particles north and south. Some of the particles released by the sun in the solar wind become trapped in this field and are propelled toward the poles, where they produce auroras through collisions with atmospheric particles.

Atmospheric composition and temperature impact the color of lightning

Just as fire ranges from red to blue with increasing temperature, lightning's blueish-white comes from the superheating of air. The emission of light from the predominantly nitrogen- and oxygen-rich atmosphere produces a purple tint, with additional color caused by light scattering from humidity, hail, dust, and ash.

How the loss of Earth's atmosphere would cause oceans to boil at freezing temperatures

Many phenomena requiring air pressure, from the flight of birds and aircraft to the act of breathing, would no longer be possible. Because sound travels through vibrating air molecules, the loss of the planet's atmosphere would also create a silent environment. Even during daytime hours, the sky would resemble a clear night sky.

Martian skies and sunsets resembled Earth's hundreds of millions of years ago

Evidence suggests that Mars has had a thicker atmosphere, which included greenhouse gases, and a magnetic field in its past, resembling Earth's current composition. After losing its magnetic field—the protection from solar wind—the atmosphere and its associated atmospheric phenomena gradually disappeared.

Tidally locked exoplanets experience extreme atmospheric temperatures

On worlds like WASP 76b, which orbits its host star approximately 3% the Earth-sun distance, temperatures on its day side can vaporize iron. Winds more than 14 times the speed of sound blow this material to its night side, where it condenses and falls as liquid metal.

How neutron stars resemble Earth, including harboring an atmosphere and 'mountains'

These stars maintain an atmosphere of hydrogen, helium, and carbon at approximately 2,000,000 degrees Celsius (3,600,000 degrees Fahrenheit), only a few thousandths of a millimeter thick, which envelops "mountains" about a millimeter high. Its interior consists of an inner and an outer crust surrounding inner and outer cores, all held together by enormous gravitational forces despite spinning multiple times a second.

Everything with a temperature above absolute zero emits light at nearly all wavelengths

Thermal radiation results from random motions of particles that make up an object, which only theoretically cease at 0 Kelvin, or -273.15 degrees Celsius. The greatest intensity of thermal radiation, also known as blackbody radiation, is emitted at a characteristic wavelength corresponding to the object's surface temperature.

Scientists have proposed using lasers to push space trash into Earth's atmosphere

Such projects would allow most debris to burn up and no longer pose a risk to active satellites, telescopes, and astronauts on space stations. Enacting these plans would require substantial investments from private and governmental space agencies and overcoming international laws that prevent the removal of another country's space equipment.

The edge of the Milky Way may be identified by its star-forming disk

Like Earth's atmosphere and its core, galaxies become more diffuse with increasing distance from their centers, making it hard to define where they end. However, one approach focuses on where gas concentrations are no longer dense enough to support measurable star formation.

How the extended life of rapidly decaying particles supports the special theory of relativity

Muons produced in particle accelerators are known to decay into other particles after about 2.2 microseconds on average, but those produced in the atmosphere live much longer—enough to travel thousands of meters to detectors on Earth's surface. As predicted by the mathematics of special relativity, by traveling near the speed of light, muons experience time passing dozens of times more slowly, allowing them to live long enough to reach Earth's surface before decaying.

The heat death of the universe will mark the perceptive end of time

Under this scenario, all matter and energy will be scattered as far out as possible, with no stars left to produce measurable light between objects. With no way of observing changes or increasing the disorder of the universe further, events could not be distinguished from one another, and time would lose meaning.

Cloud chambers use alcohol vapor to create trails behind passing cosmic rays

As cosmic rays travel through the air, they collide with molecules to form charged fragments called ions. Vapors in the chamber condense around these ions, creating streaks of tiny droplets that mark the paths where cosmic rays or their secondary particles traveled.

Visualize the anatomy of a comet

The solid nucleus holds the frozen molecules, which are heated into a gaseous state once the comet is within three times Earth's distance from the sun. The surrounding coma, from which comets get their name, is a spherical cloud that can grow larger than Jupiter, from which tails develop.

The origin of atmospheric science while testing nuclear weapons during the Cold War

The arms race between the US and the Soviet Union saw both countries stockpiling and detonating hundreds of bombs underground, underwater, and in the atmosphere. To better predict where nuclear fallout would travel after these tests, scientists developed models that would serve as a foundation for those used to explain atmospheric circulation.

Planeterrellas create artificial auroras that mimic the atmospheric displays of light by setting up an electric field between two metal balls in a jar filled with a small amount of air.

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

Dirty lightning is a thunderstorm created from friction between rising and falling flows of ash and smoke during volcanic eruptions.

See the 25 of the best photos of auroras from around the world.

See how fireworks are made and learn how metals like magnesium and copper are responsible for different colors.

Chaos theory—informally known as the butterfly effect—is the reason why weather forecasts are presented with probabilities rather than certainties.

Most of the observable universe's volume consists of voids and supervoids—enormous regions of space with little to no galaxies, stars, or light.

While the sun's gravity keeps the planets in orbit, their gravity also pulls on the sun, causing it and everything else in the solar system to orbit around a mutual balance point called the barycenter—the true center of the solar system.

All rainbows are 'raincircles' caused by water droplets separating white sunlight into a spectrum of colors, but Earth's surface blocks the bottom half of the circle from our line of sight.

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

After NASA's Voyager 1 captured Earth as a single pixel as it left the solar system in 1990, astronomer Carl Sagan used the image to reflect on humanity's fragility and the responsibility to protect 'the only world we've ever known.'

Volcanoes 'die' when their supply of magma runs out, if they are shifted away from their underlying magma reservoir, or if they get clogged by collapsing or their magma cooling back into rock.

While El Niño moves warm Pacific Ocean waters east along the equator, La Niña moves them west, shifting where rainfall will become more common for months.

Volcanic activity may have triggered the Black Death by spewing gases that led to crop failures in Europe, thus forcing the import of grain ships with plague-infested fleas.

Before writing 'Walden,' transcendentalist Henry David Thoreau nearly burned down his hometown with a campfire that grew out of control.

View the ten deadliest tornadoes in US history.

The price of gas is a composite made up of several different factors, with the federal gas tax making up less than 20% of what drivers pay at the pump.

See photos of Meteora, a mountainous site in central Greece, home to 14th-century monasteries perched atop soaring outcroppings.

In 1984, Operation Smash Hit intentionally crashed a 239-ton train into a nuclear waste canister at 100 miles per hour to prove the canister's safety, which remained completely intact and lost just 0.29 of its 100 pounds of pressure.

A 2019 Facebook event called on attendees to "Storm Area 51, They Can't Stop All of Us," resulting in countless memes, the creation of a music festival, and eventually the arrests of those who did try to approach the area.

As of 2025, the most cited papers in science include a review of graphene, methods to improve image recognition, streamlining electron density calculations, and optimizing protein studies.

For centuries, it was common to sleep in two shifts: a few hours at the beginning of the night, and a longer period beginning around midnight