The fortunate factors that make life on Earth possible

The key ingredients to life on Earth—and elsewhere

Life can only arise in incredibly specific conditions, an abundance of certain substances like water and phosphorus, lots of time, and the right proximity to a heat-and-light-providing star. These two experts on evolution of life say above all, life requires luck. Here's a list of eight ingredients to life.

Why the existence of extremophiles greatly improves the odds of life beyond Earth

The conditions for life have long been thought to include liquid water, an energy source, and the essential elements for organic molecules within environments on or near Earth's surface. However, because extremophiles thrive in far more inhospitable environments, astronomers now analyze exoplanets whose characteristics indicate environments that fall within a broader range of possibilities when searching for signs of extraterrestrial life.

Humans have existed for just 0.004% of Earth’s history

Born from the remains of the molecular cloud that birthed the sun, Earth experienced planetary-scale collisions, asteroid impacts, and lava seas. Life became possible after the planet cooled and formed a thin crust, atmosphere, and oceans.

Earth is the only planet in our solar system with fire

And while the sun seems like fire, and other planets have volcanoes, the sun and lava aren't the same thing as fire. To produce fire, a planet needs three ingredients: oxygen, fuel, and heat. No other planet has all three.

How Earth's 'greenhouse effect' works

The so-called "greenhouse effect," where various gases in Earth's atmosphere trap heat from the sun, is a crucial factor in our planet's ability to sustain life. It's also pivotal in discussions over humanity's impact on changes in the Earth's...

Besides Earth, Mars is the only possibly habitable planet in our solar system

Sending humans to Mars in the following decades poses significant challenges, from the vast distance covered to get materials there to powering technology during weekslong dust storms. Research is ongoing to develop life support systems that can regenerate or recycle consumables.

Earth is the only terrestrial planet with a magnetic field

Its magnetosphere emerges from a complex interior process of electrical conduction, heat, and motion known as the geodynamo. The magnetic field shields the Earth from unsafe cosmic radiation, providing one of the many conditions required for life.

There may be as many as 300 million potentially habitable planets in our galaxy

The estimate comes from a study using data from the Kepler space telescope—a project aimed at finding exoplanets—and considers exoplanets similar in size to Earth around sun-like stars. These have a greater potential to possess liquid water.

Panspermia, the theory that cellular life came from a different planet

One of the most profound mysteries of human life on earth is the presence of living cells: organic, self-organizing, reproducing creatures with a drive to survive within given set conditions. Traditional theories posit life came from divine...

A chemical overview of water, whose uncommon properties help sustain life on Earth

The uneven distribution of charge in water molecules allows them to bond to each other and to surfaces, enabling them to move against gravity, including up plants through roots and stems. These bonds also keep water in a liquid state over a wider temperature range and make it less dense as it freezes. This causes ice to float and form an insulating layer for underwater ecosystems, from which all life originated.

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.

Asteroids are artifacts of water's presence in the solar system

Asteroids contributed to planet formation and carried water from the solar system's outer reaches toward the center. They were also early providers of the necessary elements and conditions for life to evolve on Earth.

An overview of the sun, from its formation to its role in fueling and protecting life on Earth

With a surface gravity almost 28 times Earth's, the sun's mass exerts enough pressure to raise temperatures in its core above 15 million degrees Celsius (27 million degrees Fahrenheit) and enable nuclear fusion. These reactions produce the energy that sustains Earth's photosynthesis-dependent food chains, while the sun's magnetic field protects the solar system from cosmic ionizing radiation.

The cycling of carbon via tectonic activity may have facilitated life on Earth

Plates sinking into Earth’s mantle pull carbon from the surface, helping stabilize the atmosphere and climate by removing greenhouse gases from volcanic eruptions. At the same time, magma is a significant contributor of heavy metals and other crucial minerals for life to the surface.

Moon 101: NASA's complete overview of our lunar companion

From modulating our tides to impact our climate, Earth's lone natural satellite plays a key role forming the planet's habitat. Before diving into the rest of the resources on this page, check out NASA's overview of the basics of the Moon—how it got its name, its size and distance from Earth, its structure, and much more.

View the 55 ECVs used to describe Earth's atmospheric conditions

Essential climate variables include physical, chemical, and biological variables that meaningfully contribute to Earth's climate and how it changes with time. Many of these variables influence one another through feedback mechanisms across Earth's atmosphere, hydrosphere, cryosphere, biosphere, and geosphere.

About 99% of Earth's atmosphere is made of nitrogen and oxygen

At 78% and 21% respectively, the two elements are followed by argon with almost 1%. Trace amounts of other molecules, including greenhouse gases such as methane and carbon dioxide, and particulate matter such as dust and pollen, make up the remainder of the atmosphere's contents.

How do planets form? An interview with a planetary scientist

Dr Farzana Meru, assistant professor and planetary scientist, shares how planets come to be in this interview. Protoplanetary discs are swirling, dusty, and gaseous formations that form and revolve around stars. Some 4,000 extra-solar planets have already been discovered, and through these protoplanetary discs more are on the way.

The beauty of the Earth in 80 photos

The world is full of beautiful landscapes, creatures, and scenes. Here's a gallery of 80 incredible photos with explanatory captions to deepen your appreciation for the diverse wonders of Earth.

Ten everyday NASA inventions (likely) in your home

As a public agency, NASA's goals aren't just in space, but for life on Earth, too. That's why so many everyday objects including memory foam, cordless tools, and golf balls are rooted in research first developed by space-faring engineers and scientists. Peruse this quirky list of some of those everyday objects destined for space that are also probably somewhere inside your home.

A scientist debunks theories for why aliens might invade Earth

While TV and films offer common tropes for why aliens would invade Earth, many of those reasons aren't actually feasible. For example, a species with technology advanced enough to allow it to travel between planets likely doesn't need to enslave flawed humans to carry out its labor.

Protecting astronauts against space radiation

Outside the protective atmosphere of Earth, astronauts are constantly bombarded by radiation, which, among other dangers, increases the risk cancer. While those of us on Earth can mitigate the effects of similar radiation by limiting exposure,...

Environment and genetics explain why animals have widely different lifespans

Both environmental conditions and genetic factors shape how long various animals live. For some creatures, colder conditions allow for less energy use and slower aging. Larger animals have fewer predators. While humans don't live the longest, we are a rare species that successfully lengthened its average lifespan over time.

View a breakdown of the identified species on Earth

Over 2 million species have been documented by scientists, but there may be as many as a billion distinct species. The vast majority of the species on Earth are insects, while mammals form the smallest group.

Voyager mission's Golden Record captures Earth’s essence for alien discovery

Housed aboard Voyager 1 and 2, each record serves as a time capsule of human culture and a peaceful introduction to any intelligent life. Even if never played, the records can outlast humanity and travel through space for a billion years.

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.

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.'

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.

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.

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.

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.

SpongeBob exemplifies Aristotle's philosophy for living well because he understands that happiness doesn't come from external factors like money, recognition, or power.

Learn how your body is, scientifically, like a firework with its own slow, controlled burn.

In 2026, Finland was named the world's happiest country for the ninth consecutive year based on its wealth, social safety network, and high life expectancy, among other factors.

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.

Massive blooms of microscopic plankton called dinoflagellates produce the neon blue light seen in glowing tides.

According to the physics of black holes, our 4D reality may be a hologram—a projection of information coded on a 2D surface on the edge of the universe.

Explore the history, structure, and species of Australia's Great Barrier Reef with this interactive journey narrated by Sir David Attenborough.

The US Constitution is widely regarded as the longest-standing written national constitution still in force—see how it has influenced rights worldwide.

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

Explore fun facts from the USPS, including unique post office buildings, a stamp that traveled past Pluto, and more.

In 1939, baseball star Lou Gehrig delivered his inspirational 'Luckiest Man' speech after retiring due to the health condition that now bears his name.

Some Pokémon have been named after real and fictional organisms, while some real-world species have been named after Pokémon, such as Chilicola charizard and Binburrum zapdos.

Indefinite cloning of some endangered species may not sustain their longevity because cloning success rates decrease as genetic mutations accumulate.

Hookworm infection, though risky, may help fight certain autoimmune conditions by tamping down the immune system's inflammatory response.

Discover the catastrophic consequences of a failure of the US electrical grid—something that is more likely than many Americans think.

Apeirophobia is an overwhelming fear of living forever, perhaps stemming from the brain's inability to conceptualize an infinite life.

Scientists have struggled to pin down Ebola's natural reservoir species for decades, but the available evidence suggests that it's very likely fruit and insect-eating bats found in Africa.

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.

Venture capital is a form of funding provided to early-stage companies with high growth potential, typically in exchange for an equity (or ownership) stake