GPS satellites are programmed to account for their faster passage of time in space

Earth's core is about 2.5 years younger than its surface according to relativity

Due to differences in where objects are located within gravitational fields, time will run at different rates, which has major impacts on technology that relies on synchronization. For example, GPS satellites run about 38 microseconds faster every day than clocks on Earth's surface, resulting in GPS discrepancies of about six miles, were it not for software corrections.

The extreme precision of atomic clocks highlights gravitational time dilation

Scientists at the National Institute of Standards and Technology have constructed clocks made out of stacked strontium atoms, which show differences in the passage of time across just a millimeter of height consistent with predictions from general relativity, where atoms closer to Earth's center tick off time more slowly.

Gravity Probe B verified that rotating objects drag spacetime

The experiment involved attaching four freely floating gyroscopes to a telescope aimed at a distant star for a year. The observed angular shift of the gyroscopes as a result of Earth's rotation pulling on spacetime was approximately 0.0000012 degrees from the amount predicted by general relativity.

Where you are located in a gravitational field affects how quickly you age

The closer something is to the center of a massive object, the greater the strength of the massive object's gravitational field as a result of space-time being depressed more severely. Time passes more slowly the deeper an object is in this gravitational depression, meaning objects in the universe naturally seek to age more slowly.

Gravity assists are crucial for space travel beyond Mars

By traveling near a moving celestial object, a passing object can gain or lose speed and change direction due to the acceleration provided by their mutual gravity. Some missions are planned around spacecraft performing multiple assists, or slingshots, to reduce fuel requirements for long-distance travel.

Photons do not experience distance or the passage of time

According to special relativity, the speed of light is the cosmic speed limit, and the faster an object moves through space, the less it moves through time. As a result, particles of light only move through space and have no velocity through time, perceiving all locations they travel through simultaneously.

The moon is moving 3.8 centimeters farther away from Earth each year

Driven by tidal forces, the effect is minimal and slow, ensuring stable tidal patterns and lunar cycles. Earth's rotation slows down as the Moon gains orbital momentum, slowly lengthening the day over time.

Uncertainties in measurements make finding gravity's Newtonian limit unclear

Although Newton's "universal" law is unreliable in strong gravitational fields when compared with the field equations of general relativity, it is still taught for its accuracy on everyday scales. However, gravity's effect on small scales is too weak to be measured reliably, its accuracy at atomic scales remains unknown.

Differences in seismic wave speeds let scientists determine an earthquake’s location

Because primary waves are faster than secondary waves, seismic stations will detect longer gaps between these waves’ arrivals the farther an earthquake is. Calculating the distance to the earthquake from three stations allows its origin to be triangulated.

Five surprising things your GPS can do

You’d be surprised at all the things that GPS—the global positioning system that underlies all of modern navigation—can do. Here's a quick breakdown.

Geodesists define sea level using gravity rather than the ocean's height

The sea level is not the same everywhere because the Earth isn't perfectly spherical or has a uniform composition and density. Earth's gravitational field is carefully measured to determine where the sea level would be, even in places with no water.

Explore how far you've traveled through space while living on Earth

Using the "Cosmic Odometer," users can enter their birthday and learn how far they have moved through space due to the combined effects of Earth's rotation around its axis, the planet's orbit around the sun, the solar system's trajectory through the Milky Way, and the galaxy's motion through the universe.

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

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

Potential LIGO sites were selected in pairs, approximately 3,000 kilometers apart

The 1,864-mile distance meant gravitational wave signals would be detected no more than 10 milliseconds apart, ruling out many background signals. The sites needed sufficient plots of nearly flat land, proximity to infrastructure (e.g., electricity), and adequate distance from urban areas and geologically active areas to reduce environmental noise.

Great circles provide the shortest path between two points on a sphere

On Earth, a great circle is formed by slicing through the planet, such that one cuts through the center alongside the two locations from which the shortest distance needs to be found. The resulting arc along the Earth's surface is responsible for curved routes on flight maps, rather than straight trajectories.

Railroads and long-distance communication led to the development of time zones

Noon had been determined independently at each location based on when the sun was highest in the sky, but this became impractical for standardizing transportation. British star-mapping and navigation advancements established Greenwich as the prime meridian through Greenwich Mean Time, or GMT.

Astronomers use a set of scaffolding methods to measure distances across the universe

Different methods are used depending on how far away an object is—from radar for nearby planets, to parallax for stars, to redshift and supernovae for distant galaxies. These tools allow scientists to chart the universe across unimaginable scales using astronomical units (AU), light-years, and parsecs.

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.

Lagrange points offer energy-efficient orbits for telescopes

Lagrange Points are special locations where gravitational forces let spacecraft "park" without constant course corrections, making them ideal for science missions. NASA’s James Webb Telescope uses Lagrange Point 2 to stay aligned with Earth while orbiting the Sun.

Why do some people always get lost?

Using GPS, anthropological data, and VR, scientists have learned that one's sense of direction is largely influenced by upbringing. A person's wayfinding ability can be measured by how accurately they point toward an out-of-sight location, a challenge further complicated by imagining they're somewhere else and pointing toward a third location. Anxiety, safety concerns, and dislike of wandering can negatively impact one's sense of direction, which can improve with practice.

Rising satellite numbers pose increased risks of planes being hit by falling debris

Projections of more than 100,000 satellites in space by the 2030s—eight times the number in 2025—highlight a growing threat to aviation. Experts suggest the odds could reach seven in 10,000 annually by 2035, alongside higher risks to people on the ground.

Deep Space Network sites enable nonstop communication with distant spacecraft

Each DSN complex has multiple large, sensitive antennas that can receive weak radio signals from far-off spacecraft and send commands back to them. Their amplifiers are cooled to just above absolute zero to reduce electronic noise.

Climate data is monitored globally using tools from satellites to backyard gauges

Scientists use satellites, balloons, ocean buoys, and land-based instruments to track climate variables like temperature, precipitation, and wind. These tools gather data from deep ocean waters to the upper atmosphere.

Watch a livestream of Earth from the International Space Station

The feed is made possible by the SpaceTV-1 camera system, which is live over 20 hours a day. Video replays are shown during routine loss of signal communications with the inter-satellite link relaying the video data.

Why are all maps of the world wrong?

This 5-minute video explains why all maps to date are verifiably wrong. While globes can provide an accurate map and scale of the various continents, flattening that sphere has historically meant something will be distorted, whether land, sea, or...

What are pulsars?

Pulsars are neutron stars created as part of stellar evolution and emit radiation beams visible from Earth. These beams pulse like a lighthouse's light due to the star's rotation, creating periodic high-energy emissions. Pulsars were first discovered as radio sources; it was also discovered they emit gamma rays. NASA uses its Fermi Gamma-ray Space Telescope to retrieve and analyze data from pulsars.

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.

Astronauts have repaired genetic damage in space using CRISPR—a molecular tool that can make precise changes to DNA and is used in single-celled organisms to attack invasive viruses.

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.

Stanford built a Google Maps for the Roman Empire, revealing how much it cost to travel in the ancient world

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

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.

Visualize the path of every solar eclipse from 1900 to 2099 and see what each looks like when observed from different locations on Earth.

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 USPS spent $3.97B in 2024, accounting for .058% of the federal budget.

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.

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

Watch how algorithms can be designed to train themselves and self-improve without human input, to the point where the optimized code is too complex for programmers to understand.

Coral polyps reproduce via broadcast spawning, where entire reefs simultaneously release reproductive cells for about one hour, once a year.

US housing costs have risen by roughly 175% between 1991 and 2026—but a growing number of Gen Zers are becoming homeowners anyway. In 2025, 4% of homebuyers were Gen Z, up from 3% the year before.

Some renewable energy sources may weaken the resiliency of electric grids by removing outage buffers provided by coal- and natural gas-fired plants, which provide the system with more time to find a new power source if a plant goes down.

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

Domino's Pizza's 30-minute delivery guarantee was responsible for the chain's 1980s surge, but it was discontinued after the company was found liable for delivery driver accidents.

Recent research found that the brain doesn't seem to massively rewire following amputation—upending earlier beliefs about the cause of phantom limb pain.

Telehealth demand for GLP-1s for weight loss is booming as consumers seek easier access.

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.

While the first exchange-traded fund (a 'basket' of different assets that can be bought and sold on a stock exchange) in the US only launched in 1993, the global ETF market has grown to more than $10T in the short time since.

Long before Major League Baseball began allowing instant replay for balls and strikes, an umpire reluctantly used the technology to determine whether a hit was a home run, a move that inadvertently ushered in a new era for the sport.

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.