Geological features on Mars' surface provide evidence of massive past flooding

Mars once had oceans and a thick atmosphere

It formed over millions of years as small clumps of matter orbiting the sun smashed together, solidified, and cooled. Geological features indicate the presence of past surface water, which evaporated away due to the planet's weak gravitational field.

While geography pertains to Earth's surface features, areography pertains to Mars

Unlike Earth, Mars lacks geological activity and oceans, though geological evidence suggests they both existed in the past. Its northern regions have far fewer craters than the southern ones, indicating that the rock in the north formed more recently.

Mars features distinct geographic contrasts between its northern and southern regions

Unlike the uniform terrains found in most rocky planets, Mars has a smooth, low northern hemisphere and a rough, high southern hemisphere with much thicker crust. This dichotomy may originate from a massive collision early in the planet’s history.

Some 19th century astronomers thought Mars was inhabited

As telescope technology advanced, astronomers became able to observe the surfaces of objects in our solar system with greater detail. The dips, valleys, and lines crisscrossing Mars, particularly, captured onlookers' imagination, leading some to speculate that the seemingly organized features could only have been created by an intelligent civilization.

Fly through the Valles Marineris, the largest canyon in the solar system

Stretching farther than the width of the continental US and with depths as much as four times those of the Grand Canyon, the Valles Marineris is believed to have formed when Mars’s crust tore open during intense volcanism in the planet’s past.

Explore a world map of Mars

The yellows spots scattered across the map indicate meteor impacts while the red regions represent volcanoes and their associated lava flows. The varying shades of brown indicate cratered highlands and midlands, which make up most of the southern hemisphere.

Dust particles on Mars can generate lightning

Through triboelectric charging, sand and dust on the Martian surface can become electrified when they rub against one another, causing friction to displace electrons and create charged particles. If this matter forms a strong enough electric field, it can overcome atmospheric insulation and produce electrical discharges, resembling lightning on Earth.

What is Mars Curiosity rover up to?

Mars continues to reveal itself through the Mars Curiosity Rover, which continues to ramble and roll across the red planet's surface. Here is NASA’s real-time portal for Mars exploration, featuring the latest news, images, and discoveries from the Red Planet. See evidence of the ancient rivers that once ran through the martian landscape, and see how Curiosity is setting the scene for possible future exploration by humans.

The Viking landers were the first spacecraft to conduct experiments on Mars

NASA’s Viking 1 and 2 missions tested soils for signs of life, captured images, and studied the Martian atmosphere, revealing evidence of ancient water flow, volcanic soil, and a thin carbon dioxide atmosphere.

A history of water on the moon

Is there water on the moon? In 2020, NASA's SOFIA mission confirmed the existence of water on the sunlit area of the lunar surface. Early astronomers mistook the dark spots on the Moon for oceans, but they are actually plains of dark, lava-produced...

Atmospheric rivers are the largest freshwater transport mechanism on Earth

Serving as highways that carry the water vapor equivalent of up to 15 times the average flow of water at the mouth of the Mississippi River, atmospheric rivers are approximately 400 to 600 kilometers (250 to 375 miles) wide and provide 30-50% of the annual precipitation of the US West Coast.

Supersonic parachutes have allowed rovers to safely land on Mars' surface

The disk-band-gap parachute design was first developed for the Viking Project in the 1970s. Since then, it has been reinforced and uses stronger materials to handle larger payloads—including the 2020 Perseverance rover—landing it a world record.

Why extremophiles may play an important role in terraforming Mars

Possessing unique biochemicals that can detoxify extreme environments and resilience against the Martian surface that is lethal to humans, scientists are exploring whether colonies of these organisms can transform small areas of the Red Planet into future habitats for humans. Extremophiles may also be best equipped to serve as microscopic factories for the fabrication of essential polymers.

What can be found underneath the Saharan sands?

Watch this 19-minute video to learn more about what can be found under the Sahara Desert, which spans almost all of northern Africa and is one of the largest deserts in the world. Deep under the Sahara desert sands lies evidence of life that once...

Explore landforms that exist across America's national parks

Landforms are not just scenic vistas; they are geological storytellers that shape ecosystems, climates, and our understanding of Earth's history. In this comprehensive look at landforms from the National Park Service, you will learn not only about different types of American landforms, but you will understand how these geological features are shaped by various forces, how they reveal an area's geological history, and how they influence climate and ecology.

Supermassive black holes create pressure waves, detectable as extremely low sounds

Space is largely silent because it lacks a medium for sound waves. Some Mars rovers capture sounds of wind, though the sounds are too low to hear. Through sonification, astronomical data can be translated into hearable sounds for broader engagement.

Continental drift is supported by matching evidence across disconnected continents

Mesosaurus fossils are found in South America and Africa, but these freshwater creatures could not have travelled across the ocean between continents. Rock layers in the Appalachian Mountains match those seen in Europe, indicating that the mountain belts were once connected.

Sinkholes form when underground cavities cause the surface above to collapse

These openings are typically carved by acidic water, which often forms in limestone-rich areas. However, leaking pipes, groundwater removal and extreme weather or geological activity increases the frequency of sinkhole appearances.

Niagara Falls flows over 400-million-year-old layered rock

The falls cut through distinct layers of ancient rock: a hard cap of Lockport Dolomite sits atop softer layers of Rochester and Queenston Shale. This structure allows the falls to maintain a steep vertical drop as erosion undercuts the caprock.

Could water scarcity cause future wars in the Middle East?

The MENA region is facing a looming water crisis that could lead to future conflicts. While water scarcity isn't new in the Middle East, the region is among the most water scarce in the world. Home to only 1% of the world's fresh water...

Explore and visualize AI-driven global flood forecasts in 'Flood Hub'

Google's tool provides water trends, real-time flood forecasts, local inundation maps, and flood alerts, using AI models and available data to help people and institutions take action up to 7 days before a flood.

How humans are engineering the planet

One fact about our time is becoming increasingly well-known. No matter how far you travel, no matter in which direction you point, there is nowhere on Earth that remains free from the traces of human activity.

View colorful flowers that grow on cacti and succulents, popular xerophilic organisms

These dry-loving organisms are able to retain the water they need to grow and reproduce in deserts and arid grasslands through a suite of adaptations, including thick, fleshy stems that store abundant water, a waxy coating that helps prevent water loss, and an uncommon form of photosynthesis that loses less water.

Lidar's discoveries: 32 forts revealed by the laser tech

Lidar is a cutting-edge tool using lasers from an aircraft to map the elevations of huge swaths of land across the world. This technology has been especially effective in archaeology. It has revealed dozens of lost major historical sites concealed beneath overgrown brush and forests. From Canadian forts to Mayan settlements, check out these 32 significant finds from lidar.

Why water towers are built that way

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.

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.

Waves off the coast of Nazaré, Portugal, can reach over 100 feet and are caused by the area's deep underwater canyon geography

Graffiti dates back to at least ancient Pompeii, where citizens scrawled messages to one another on public walls

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.

For centuries, Niagara Falls has been a magnet for daredevils seeking to conquer one of nature's most powerful wonders, with its 200-foot drop and water rushing at 32 feet per second with 280 tons of force.

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.

'Grand Canyon of the Yellowstone,' a work by American painter Thomas Moran, inspired Congress to establish Yellowstone National Park.

Explore our favorite visualization of the immense scale of space, from an astronaut to the size of the observable universe

Apollo astronauts left items in the moon's 'toss zone,' including golf balls, family photos, and bags of human waste, to make room for lunar rocks.

SpaceX's S-1 or 'prospectus' revealed many previously unknown details about the company, including its unprofitability despite doing $18.7B in revenue in 2025, exactly how many voting shares Elon Musk will have in the company (roughly 85%), and more.

The use of fungi to detoxify land and water—a process known as mycoremediation—has been used to clean up natural resources affected by the 2025 California wildfires.

The Great Salt Lake's distinct dual coloration results from high-salinity organisms that only live in the northern portion and produce a purple protein.

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.

See a 3D reconstruction of Tenochtitlan, the Aztec capital that was home to an estimated population of 200,000 to 400,000.

Massive 3D printers have been used to build homes by stacking layers of 'concrete toothpaste,' a fire-resistant material that effectively insulates against outside noise.

Take a 3D tour of the Hajj, Islam's annual pilgrimage to Mecca, undertaken by over 1.5 million Muslims.

Planarian flatworms are small, aquatic worms with exceptional regenerative capabilities. When cut, the worms can regenerate multiple bodies in a matter of weeks.

Gerrymandering works through two techniques: cracking opposing voters across districts to dilute their power, and packing them into a few to waste their votes in lopsided majorities.

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

The American Society of Civil Engineers' infrastructure report card gave the US a C in 2025, its highest grade since the project launched in 1998.

Fear or disgust related to clusters of holes and cracks, called trypophobia, may stem from evolutionary processes to help us avoid pathogens.

Researchers believe the brain consolidates memories, processes emotions, and plans for the future during dream states

View the ten deadliest tornadoes in US history.

Iran's Revolutionary Guard Corps is independent of Iran's regular army and is one of the most powerful and influential military-political organizations in the Middle East.