What is the Kuiper Belt?

There may be over one trillion comets in the Kuiper Belt

Named after Gerard Kuiper, who theorized the existence of a band of icy objects beyond Neptune in 1951, direct evidence for its existence did not arrive until 1992, when the first trans-Neptunian object, besides Pluto and its moon Charon, was observed. Comets with periods of less than 200 years originate from this belt.

Comets in Pluto's orbit contributed to its demotion from planetary status

In 2006, the International Astronomical Union formally defined a planet as an object in orbit around the sun with a nearly spherical shape and an orbital path clear of significant debris. Because Pluto shares its neighborhood with comets from the Kuiper Belt, it was reclassified as a dwarf planet.

The Oort cloud, our solar system's theoretical icy shell

Recurring comets lead astronomers to believe they originate from an extremely distant, icy shell encapsulating the solar system. They call it the "Oort cloud," and this giant swarm of icy objects is as fascinating as it is is massive. Home of comets and a tremendous number of planetesimals, this NASA site introduces you to the Oort.

Categorization of celestial objects has changed over history

Once classified as planets, Ceres and Vesta are now considered a dwarf planet and an asteroid, respectively. The discovery of many similarly sized objects led to the creation of the asteroid belt category.

An interactive look at Neptune, the distant planet

Dark, cold, and whipped by supersonic winds, Neptune is a gas giant made of hydrogen, helium, ammonia, and methane, and was the first planet discovered through mathematics rather than direct observation. It's also the smallest of the gas planets on the periphery of the solar system. Learn more about the last planet in the solar system through the NASA site.

Asteroids are the rocky remains of the solar system's formation

These celestial bodies were not integrated into the precursors of planets about 4.6 billion years ago and instead continue to orbit the sun, primarily within a band between Mars and Jupiter—the asteroid belt.

Evidence for a ninth planet in our solar system

Is there a massive ninth planet on the edge of our solar system? Many of our solar system's most distant objects tend to swing out in one direction, hinting at evidence for a previously unknown ninth planet potentially larger than Earth. This theoretical planet's orbital period is estimated to be roughly 20,000 years, revolving around the sun at a distance of 60 billion miles. Experts break down the evidence in this quick video.

Ice found in another star system for the first time

NASA's James Webb Space Telescope has discovered frozen water in a young star system. The ice is similar to that found in Kuiper Belt objects in our solar system, and provides insights into planetary formation processes.

Hot Jupiters are giant planets that orbit very close to their host star

Discovered in 1995, hot Jupiters are a class of exoplanets—planets orbiting stars other than the sun—with size and mass similar to Jupiter. They are most commonly found orbiting metal-rich stars and have become essential for testing theories of planetary system formation.

The rare exoplanets orbiting distant pulsars

Pulsars are ridiculously volatile, massive, and super-dense. These objects are spread out around the universe, and their spinning magnetic fields blast out radioactive pulses. Rarely, some have planets orbiting them. There's not much hope for life there—pulsars emit regular deadly radiation—but they're still fascinating from a scientific perspective. This article further explores these amazing exoplanets.

NASA monitors potentially hazardous asteroids and comets

Established in 2016, the Planetary Defense Coordination Office characterizes and tracks asteroids and comets passing within 30 million miles of Earth. Over 40,000 near-Earth asteroids have been discovered, although estimates suggest that about 14,000 more such objects remain to be found.

Are there any planets in the universe that aren’t round?

We think of all planets as spheres, but do they have to be spheres? To be classified as a planet, an object has to be sufficiently massive to reach a spherical shape through gravity. However, this doesn't mean they're perfectly round; for example, Earth has a slight equatorial bulge caused by centrifugal force from its rotation. Other observed planets feature tear-shaped formations while theorists posit donut-shaped planets. Read more here.

The most mysterious (known) star in the universe

Something massive, with roughly 1,000 times the area of Earth, is blocking the light coming from a distant star known as KIC 8462852. One of astronomers' more intriguing theories: Alien technology. Discovered via NASA's Kepler space telescope and a...

Studies show the asteroid that killed the dinosaurs was from the outer asteroid belt

Isotopic evidence confirms the rock was a carbon-rich asteroid, likely born beyond Jupiter and later knocked into Earth's path after billions of years of orbital drift and gravitational nudges. Its path spanned over 4 billion years and ended in the extinction of 75% of life, including all nonavian dinosaurs.

A map of every object in our solar system

The infographic from 2020 illustrates the complexity of our solar system, mapping over 18,000 objects including asteroids, comets, planets, and moons. Created by biologist Eleanor Lutz using data from NASA, it shows the non-linear distribution of objects due to the sun's gravitational pull. Objects nearer to the sun are more numerous, forming tighter orbits, while those farther out are fewer and more widely spaced.

The CCZ is believed to harbor trillions of dollars of valuable minerals and thousands of undiscovered species

Located between Hawaii and Mexico and spanning an area larger than the European Union, the Clarion-Clipperton Zone is the world's region with the most contracts awarded to groups seeking to extract valuable metals by collecting polymetallic nodules. Conservative estimates suggest that 21.1 billion tons of polymetallic nodules exist in this abyssal plain, but about 90% of the species in the area are unknown to scientists.

Explore the known asteroids, comets, and spacecraft involved in asteroid studies within our solar system with 'Eyes on Asteroids,' a 3D visualization from NASA.

The Kármán line is a suggested boundary between Earth and outer space

Beyond this line, approximately 100 kilometers above Earth's surface, aerodynamic lift is insufficient to keep aircraft aloft without special propulsion systems. The United Nations has historically accepted the line as delineating the boundary of space.

The missing continent that took 375 years to find

It took scientists 375 years to discover the eighth continent of the world, which had been hiding in plain sight all along. But mysteries still remain.

If the universe is infinite, it may be impossible to say what's beyond it

The universe is defined as all that exists, including space and time. If the universe is infinite, as observations currently suggest, there is no boundary from which we can ask what lies beyond.

As of 2025, over 131 million pieces of debris orbit Earth

These pieces range in size from a grain of sand to the size of a bus and orbit with an average speed of 10 kilometers per second.

Astrobiology is the study of life's origins and the search for life beyond Earth

The field incorporates observational missions to find and classify exoplanets—planets orbiting stars besides the sun—the probing of Earth's most extreme environments to learn what conditions allow life to exist, and theoretical and lab work to identify and analyze potential biochemical signatures.

Everything you need to know about Mars

The Lunar and Planetary Institute provides assorted resources about the red planet, Mars. Review this basic 101 level introduction and get to know our solar system neighbor. Learn about Mars' planet-wide dust storms, staggeringly high mountains (six of which dwarf Mount Everest), and whether there's water there below the surface.

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

Why parts of the Earth are colder when the planet is closer to the Sun

The Earth orbits the Sun in an elliptical shape, and winter in the Northern Hemisphere occurs when the Earth reaches the point in its orbit closest to the Sun, known as perihelion. The lower temperatures result from the hemisphere tilting away from the Sun.

The X-37B is America's secretive long-duration space plane

The second iteration of the Space Race is already heating up between the US and China, with both countries working to develop technologies for space superiority. Among those, the X-37B has stoked fears in Beijing that the vehicle could one day deliver powerful weapons from space.

Launched in 2020, NASA's Perseverance rover was equipped with a deployable helicopter

Nicknamed "Percy" and designed as the successor to the Curiosity rover, the vehicle has covered more than 36 kilometers (22 miles), collected dozens of samples, and taken hundreds of images while searching for signs of ancient microbial life.

Track the location of the Voyager probes, currently between 13 and 15 billion miles away from Earth.

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

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.

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.

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.

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.'

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.

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.

Watch how deep-sea mining equipment collects and processes polymetallic nodules—metal-rich, potato-shaped rocks—from the ocean floor and creates environmentally damaging plumes of sediments.

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.

In 2025, four executives from large tech companies were given positions in the US Army Reserves—including Palantir Chief Technology Officer Shyam Sankar, which reinforced Palantir's ties with the US military and its role as a leading defense partner.

Hurricanes, which rely on air consistently spinning in the same direction, cannot cross the equator because air curves in opposite directions north and south of it.

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

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.

The American cockroach is actually from Africa, an apparent hitchhiker aboard ships carrying enslaved people, with evidence suggesting the bug may have arrived in the New World as early as the 1600s.

In 1963, a basement renovation in Turkey revealed a passageway to a hidden, multilevel underground city that once housed as many as 20,000 people

Corals are themselves not coral reefs—the term refers to the tiny marine invertebrates that build the rigid reef.

The hormonal disorder PCOS was renamed PMOS in 2026, a move designed to improve care and research by shifting the focus to the hormonal causes of this condition that affects 1 in 8 women.

'Saturday Night Fever,' the 1977 film that introduced disco to the mainstream, was based on a fabricated magazine story.

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.

Georgia O'Keeffe's flower paintings are often assumed to be sexual, though the artist claimed she was simply interested in highlighting the beauty of flowers that most people neglect

About 2,000 US babies are born annually without some portion of their limbs, potentially leading to a lifetime of pricey prosthetics.

Hedge funds, the private investment firms that trade a wide swath of financial assets, make money by imposing steep fees on investors and from the fund's investment performance.