Visualize the anatomy of a comet

Comets serve as time capsules of the early solar system

The frozen objects preserve the molecular composition of the solar system's formation, dating back about 4.6 billion years. Spectral analysis of the gases they release when heated upon approaching the sun in eccentric orbits reveals this composition and helps assess solar system formation models.

The composition of comets earned them the nickname 'dirty snowballs'

The icy relics of the solar system are composed of rock, gravel, dust, and frozen molecules, such as carbon dioxide, carbon monoxide, methane, ammonia, and water. Once close to the sun, these compounds sublimate into gases, creating a fuzzy cloud that earned the comets another nickname in history: hairy stars.

A comet's tails point away from the sun, rather than trailing its motion

The ion tail, composed of gases ionized by solar radiation and pushed by the solar wind, points away from the sun. In contrast, the dust tail is pushed away by radiative pressure and curves away from the comet's motion. As the comet approaches the sun, both tails get longer.

Dark comets appear to be rocky asteroids but move like comets

Cometary orbits are known to exhibit accelerations independent of gravity that result from forces related to the release of gases. Dark comets exhibit this behavior but lack visible clouds of frozen material that have turned into a gas—the coma the comets display—indicating minor quantities of escaping subsurface ice.

Explore a guide to observing comets

Binoculars or telescopes can be used to see vivid tails, glowing comas, and brief bursts of brightness from these celestial objects. For photography, a DSLR or mirrorless camera with a wide-aperture lens, long exposure settings, and accessories such as tripods and star trackers is recommended.

Find which comets are currently visible in the night sky

Incorporating sightings reported in the Comet Observation database and information from NASA's Jet Propulsion Laboratory, this list provides a finder chart, star map, tracker, simulated orbit, and key properties for each comet, all viewable based on a user's input position on Earth.

Comets can be categorized based on their orbital period

Short-period comets orbit around the sun once every 200 years or less and are made up of Jupiter-family (less than 20 years) and Halley-type (between 20 and 200 years) comet subgroups. Long-period comets have orbits greater than 200 years, while exocomets originate in solar systems outside our own.

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.

View a gallery of notable comets

The collection features 1973's Kohoutek, which had been dubbed the "comet of the century," 1965's Ikeya-Seki—one of the brightest comets of the millennium—and 2002's NEAT, a comet that survived a coronal mass ejection as it passed near the sun.

Watch a visualization of the formation of the planets

The nebular hypothesis proposes that a swirling cloud of gas and dust coalesced into a dense center, forming a star amid nuclear fusion. Lighter elements were blown far from the star while heavier elements remained nearby, serving as primary materials for terrestrial and jovian planets, respectively.

An overview of atomic composition, scale, and structure, which is almost all 'empty' space

It takes about 500,000 carbon atoms lined up next to one another to span the thickness of human hair, and over 99.9994% of the mass of each is contained in the nucleus. About 99.999999999999% of an atom's volume lies outside this nucleus, where electrons exist in clouds of probability. Removing these clouds, the Empire State Building would be the size of a rice grain.

Read about the dangerous comet behind the Perseids meteor shower

Every summer, Earth passes through the debris trail of the Swift-Tuttle comet, producing the spectacle of the Perseids meteor shower. The phenomenon is a glorious opportunity for amateur stargazers, but astronomers have long noted the comet's orbit...

In 1994, fragments of comet Shoemaker-Levy 9 crashed into Jupiter

Hubble captured the collisions, which created massive black impact sites visible from space. It represented the first time scientists could prepare for, and observe, an interplanetary collision in real time, allowing them to gather valuable information about Jupiter's atmosphere.

The names of comets can change based on subsequent observations

The International Astronomical Union's coded naming system uses the first letter to indicate a comet's category, which can change over time. "D" represents comets that have been lost or broken up, while "A" applies to former comets that are now asteroids or dwarf planets.

As of 2025, scientific evidence strongly supports 3I/ATLAS being a comet

Claims of alien technology would require the celestial object to transmit measurable technological signals, which were not detected by the world's largest fully steerable radio telescope. Previous telescope observations identified that 3I/ATLAS's chemical composition, structure, and orbital characteristics are consistent with those of an interstellar comet.

Deep Impact was the first mission to probe beneath a comet's surface

The NASA mission sent a probe to deliberately crash into comet Tempel 1, producing an explosion equivalent to 4.7 tons of TNT. The payload included a compact disk with more than 625,000 names of people who participated in the "Send Your Name to a Comet!" campaign.

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

Cloud formation requires water vapor and condensation nuclei to build from

The nuclei—particles like dust, salt, and smoke—act like jumpstarts that water molecules can start to accumulate onto to form clouds. Condensation nuclei are about 1/100th the size of cloud droplets, which are mostly water.

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.

Neutron stars, the remains of some massive stars after they explode in a supernova, are the densest directly observable objects in the universe.

Violent storms and crushing pressure await those inside Jupiter’s Great Red Spot

As seen from space, Jupiter’s most striking feature is an anticyclone 30% larger than Earth, with winds twice the speed of Category 5 hurricanes. The descent into the storm brings enough pressure to strip atoms of their electrons.

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

Atmospheric gases are dense enough in this region to begin burning up debris traveling toward Earth's surface, producing meteor showers, or shooting stars. Although we normally associate decreasing temperatures with increasing altitude, temperatures increase beyond the mesosphere layer due to the absorption of high-energy ultraviolet radiation and X-rays.

Take a journey to the Earth's core

This animated video takes you on a journey through the different layers of the Earth's core, with insight into what makes up each shell. Earth's outer core, which is about 1,400 miles thick, is made up of liquid iron and nickel at a blistering...

Visualizing Earth's space garbage

An unsavory byproduct of humanity's brilliant exploration of space, the Moon, and more, is the rapid production of space debris floating around in orbit. Its estimated over 25,000 objects are in orbit, a number that grows everyday as satellites are decommissioned, rockets enter orbit, and more. Now, you can visualize what this debris looks like from a zoomed-out perspective with this brief video.

Neutron stars, the remains of some massive stars after they explode in a supernova, are the densest directly observable objects in the universe.

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.

View a simulation of the dark matter filaments that make up the cosmic web

The distribution of matter in the universe is not uniform, with interconnected threads of galaxy clusters surrounded by voids of empty space. Simulations of the universe show this is only possible within 13.8 billion years—the universe's age—if a foundational network of seeds—dark matter halos—were present to gravitationally attract visible matter.

Visualize the components of fireworks

This article provides animated diagrams depicting how different parts of fireworks function. The elements work together through timed mechanisms to produce desired effects.

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

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

NASA captures image of ghostly cosmic hand

NASA's X-ray space telescopes, Chandra and the Imaging X-ray Polarimetry Explorer, have joined forces to study a hand-shaped structure in space, revealing the magnetic field "bones" of a pulsar wind nebula. Pulsars are rotating neutron stars with strong magnetic fields, creating extreme physics conditions. The combined data from these telescopes provide insight into how pulsars inject particles into space and shape their environment, with the magnetic field playing a crucial role.

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.

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.

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.

Objects can be 3D printed with light by projecting 2D computerized tomography (CT) scans onto rotating cylinders of resin, which solidify upon exposure.

Against his wishes, Albert Einstein's brain was removed before his cremation, and the pathologist responsible stored it for decades in mason jars within a beer cooler.

Browse a detailed visual analysis of over 200,000 similes—comparisons that often use 'like' or 'as'—from popular fiction to see how frequently writers the same idiomatic expressions.

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

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.

Explore chaos in this simulation of two double pendulums, where small differences in the release angles produce wildly different outcomes.

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.

Memecoins are a type of cryptocurrency—a form of digital currency with a wide variety of uses—created around popular 'memes,' or viral internet jokes.

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.

Learn how to read a prospectus, the juicy document that any company must file with the SEC before going public.

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

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.

Sunflowers have long been a symbol of nuclear disarmament because they can extract large amounts of radioactive cesium from soil.

Ebola is a filovirus, meaning it resembles a thread under a microscope, though it sometimes twists and can resemble a bowl of spaghetti.

View the ten deadliest tornadoes in US history.