Atmospheric drag is causing the Hubble Space Telescope to drift toward Earth slowly

Between 1993 and 2009, Hubble was serviced for repairs and upgrades 5 times

Across 21 space walks totaling 144 hours, replacement instruments, gyroscopes, solar arrays, batteries, and computer systems have helped extend the Hubble Space Telescope's operational lifetime beyond its planned 15 years.

Space telescope development was driven by a desire to bypass Earth's atmosphere

The most important figure in the effort to create what would become the Hubble Space Telescope was Lyman Spitzer, who first proposed a telescope in orbit in 1946. The nearly 50-year endeavor led to space-based observatories, which are not limited by Earth's atmosphere absorbing or distorting most wavelengths of light.

The International Space Station is slowly falling due to atmospheric drag

To stay in orbit, the largest human-made object in space needs periodic rocket boosts to maintain its orbital speed and height. Its solar panels collect enough energy to power over 60 average US homes each year.

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.

See where the James Webb Space Telescope is in space right now

Webb travels through space in a stable orbit, but unlike the Hubble, it doesn't orbit around Earth. The Webb orbits around the sun in a way that allows it to always be in line with the Earth, as you can see in this visualization of the telescope's real-time position.

The Challenger disaster delayed the launch of the Hubble Space Telescope

The 1986 explosion of the space shuttle shortly after liftoff killed seven crew members and grounded NASA's space fleet. Scientists used the downtime to refine ground control software and upgrade telescope instrument sensitivity, but maintaining the telescope's clean room storage cost NASA approximately $6M per month.

An imperfection 1/50th the width of a human hair blurred Hubble's initial images

Not all parts of the space telescope's primary mirror focused incoming light to the same location, an effect known as spherical aberration. Because Hubble was designed to reside in low Earth orbit and be serviced by astronauts, service missions were deployed in the years after its launch to conduct repairs.

By 2030, experts estimate a 1 in 1000 chance of a plane being hit by space debris

As more satellites and spacecraft are launched, the rate of space debris re-entering Earth's atmosphere, including those that do not burn up completely, increases. International space agencies and air traffic control systems will need to coordinate to develop standardized methods and technical solutions to prevent and minimize future crisis scenarios.

Play an interactive game to explore and learn about Hubble images

Aboard the fictional USS Hubble, users can choose their own adventure to investigate the solar system, our galaxy, and the universe beyond. Each option directs users to a real image accompanied by relevant information and additional media elements, such as a time-lapse of the moon Phobos orbiting Mars.

An early burst of dark energy may resolve discrepancies in the universe's measured expansion

The Hubble tension refers to mismatches in the calculated rate of expansion of the universe derived from different methods, such as supernova data and the cosmic microwave background. By allowing dark energy to become active at a different time, models of the universe on which some of these methods depend are revised, altering the calculated values.

Why Earth's atmosphere constantly loses the universe's lightest elements to space

The masses of hydrogen and helium are too small for these gases to be held by Earth's gravitational force, particularly when these atoms are given energy from collisions with high-speed particles from the sun. Although the planet loses a meter-wide balloon's worth of hydrogen every second, it will still take billions of years to exhaust the planet of this element.

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.

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.

Understanding why suction cups rely on Earth's atmosphere to work

When pressed against a surface, air is squeezed out of a sealed volume, causing the internal pressure to drop below the surrounding atmospheric pressure, and this imbalance creates the "sticking." For this reason, astronauts do not use suction cups or related technologies to stay on spacecraft during spacewalks.

Planets' high orbital speeds prevent them from falling into their host star

Although the gravitational force attracts a planet and the star it orbits around, the large speed the planet orbits with, which is acquired during its formation process, causes it to continuously miss the star as it orbits around it. This is analogous to theoretically throwing a baseball horizontally faster and faster until it's fast enough to orbit the Earth while attempting to fall to its surface.

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

Voyager science teams still collect valuable space data using four active tools

These instruments track magnetic fields, solar wind particles, radio emissions from the heliopause, and hydrogen levels in the outer heliosphere. Even though each Voyager sends data at just 160 bits per second, NASA receives 6–8 hours of tracking data daily.

Asteroids are often unobserved until they are days away from Earth

Even those large enough to cause local or regional damage are too small, dim, and far away to be observed readily from cosmological distances. New tools, like NASA's NEO Surveyor telescope, aim to address gaps in detection systems.

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.

Voyager Station, the world's first space hotel, is planned for 2027

The structure spans 488 meters in diameter and will rotate to simulate one-sixth of Earth's gravity while circumnavigating the planet every 90 minutes. The Voyager Station is designed to accommodate 450 guests and 150 crew members, providing amenities such as restaurants, a sports hall, and a movie theater.

The Milky Way only has a 50-50 chance of merging with the Andromeda galaxy

Previously considered a near certainty, research data from Hubble and GAIA have reduced the likelihood of a collision and merger between the two galaxies. Instead, the data suggests the Milky Way will absorb the Large Magellanic Cloud, a dwarf galaxy, in the next two billion years.

Zooming out from Earth to the edge of space

For perspective on the universe's absolute massiveness, watch this four-minute video. Beginning at a facility in Germany, the "camera" pulls back revealing the surrounding countryside, Germany itself, Europe, the Earth, and so on. At one point stars form galaxies and galaxies, at a distance, become as seemingly "small" as the individual stars.

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.

Astrobee is a free-floating robotic system helping with routine tasks on the ISS

Three cube-shaped robots use electric fans to fly through the microgravity environment of the International Space Station. They are equipped with cameras and sensors that allow them to "see" and navigate their surroundings to take inventory, document experiments, and move cargo.

Some online users believe gravity will 'switch off' for 7 seconds in August 2026

Conspiracy theorists believe NASA is preparing for the gravity blackout under a classified operation called "Project Anchor." They speculate that the purpose of the secret project is to test whether Earth can survive such an event. NASA has rejected the claim. Considering the physics of a gravity blackout, the outcome would likely be chaotic but not total destruction.

The next generation of gravitational wave detectors may include a triangular design

The Einstein Telescope will use three pairs of underground detectors—each with arms separated by 60 degrees—arranged in an equilateral triangle. The European observatory will work alongside the Cosmic Explorer, a pair of new US detectors, to provide an eightfold increase in sensitivity over LIGO and extend the current detection frequency range.

Observations from Hubble contributed to Pluto's demotion from planetary status

Before the flyby of Pluto by the New Horizons spacecraft, the Hubble Space Telescope provided images of Pluto and its moon Charon, which was similar in size. Rather than a unique ninth planet, Pluto became reclassified as a dwarf planet, like many similar objects in the Kuiper Belt.

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.

The first image of a black hole was captured by creating an Earth-sized virtual observatory from a network of eight radio telescopes.

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.'

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

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

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.

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.

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

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.

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.

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

Human-to-human transmission of hantavirus remains extremely rare, so the 2026 hantavirus cruise ship outbreak doesn't mean we're facing a COVID-style pandemic risk.

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.

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.

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.

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.

In 2009, the nation was gripped by the story of a missing young boy who was believed to be floating over Colorado in a homemade balloon, until it was revealed that he was at home the whole time.

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year

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.

Electrical grids worldwide must double their power delivery capacity by 2050 to meet surging demand from AI and electric vehicles.

The Mona Lisa's celebrity status and repeated restorations have obscured what made the painting so revolutionary for its time

The United States has had a tumultuous relationship with Cuba since its 1959 revolution, highlighted by a nuclear crisis and a decades-long trade embargo.

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.