The moon may have formed in as few as five hours after the cataclysmic collision between Earth and a long-lost protoplanet, new simulations suggest. The surprising findings could help shed light on other historic impacts throughout our cosmic neighborhood and beyond.

Experts strongly suspect that the moon was created when a Mars-size space rock called Theia smashed into an early version of our planet, back when the solar system was young and extremely unstable. This colossal impact likely would have turned the once-neighboring worlds into spinning clumps of molten rock that eventually coalesced and cooled into the versions of Earth and the moon we see today. Without this collision, which also may have left chunks of Theia buried deep within our planet, many scientists think that life may have never existed on Earth.

Lunar rocks collected during NASA's Apollo missions have provided evidence to support this theory, dubbed the giant impact hypothesis. These samples also tell us that the moon is around 4.5 billion years old, meaning the collision occurred roughly 100 million years after the sun was born. But although scientists have previously simulated the impact event, it has been tricky to ascertain exactly how the moon formed and how long it took to emerge after the Earth-Theia collision.

In the new study, published Sept. 1 in The Astrophysical Journal Letters, researchers conducted a series of simulations focusing on the varying potential geological properties of both Earth and Theia prior to their collision. This factor has been relatively understudied until now.

"When you simulate the Earth and the moon as colliding bodies with [different] geologic properties, it changes how the moon forms out of that impact — that's something we considered unnecessary before," study first author Adeene Denton, a geologist and planetary scientist at the Southwest Research Institute in Boulder, Colorado, said in a statement.

Until now, simulations of the Earth-Theia impact have focused mainly on the masses of the colliding neighbors. But in the new study, the researchers were most interested in the material strength of the two bodies, particularly the hardness of their exteriors.

"Models have evolved to include material strength, something that's really important when you're studying collisions between smaller bodies like asteroids," Denton said. "We weren't sure if it would matter for the moon or not. When we did the simulations, we found it actually matters quite a bit."

The main factor in the strength of colliding bodies is temperature. Both Earth and Theia were very young when they smashed together, so they were still hot and had soft or molten surfaces. These properties would have cushioned the collision, allowing the debris to stay largely intact and enabling the moon to form more quickly. But when the giant impact hypothesis was first proposed (in 2001), researchers initially thought the collision occurred much later, meaning that the bodies would have cooled and become more brittle. In this case, their collision would have created a larger field of rocky debris that would have taken longer to coalesce.

Researchers simulated the collision using a range of potential temperatures and found that under the most extreme scenario — where the pair were at their hottest — the moon could have formed in just five hours. However, this is just one potential outcome, and there is no way of knowing exactly how hot — and, therefore, how strong — Earth and Theia really were when they smashed together.

When the moon took shape, it was initially covered with a magma ocean that took hundreds of millions of years to solidify. Even then, its increased proximity to Earth meant that it was likely a volcanic hellscape. However, over time, it moved away from our planet, cooling further, and it is now assumed to be geologically dead. (The moon is continuing to slowly move away from us and could eventually escape our planet's gravity entirely, if the dying sun doesn’t destroy it and us first in around 5 billion years.)

The new simulations highlight the importance of material strength in planetary impact modeling, which could change what we know about other ancient collisions, like the one that knocked Jupiter's moon Ganymede off its axis or the one that birthed Saturn's moon Titan.

Additionally, the findings could have implications in the search for exomoons — the hypothetical moons of distant exoplanets, which have so far remained elusive, according to Live Science's sister site Space.com. Until now, one of the main ways astronomers have been hunting for these alien satellites is by looking for debris fields around exoplanets. However, if the moon is anything to go by, these debris fields could be very short-lived and difficult to identify.

This iconic photo, captured by an American astronaut on board the International Space Station (ISS), shows a lengthy trail of thick smoke pouring across New York City in the immediate aftermath of the 9/11 attacks. A quarter of a century later, the image is as haunting as ever.

On the morning of Sept. 11, 2001, members of the terrorist group al-Qaeda hijacked four passenger airliners and crashed two of them into the twin towers — a pair of 110-story skyscrapers at the heart of the World Trade Center in lower Manhattan. The impact of these collisions, which occurred roughly 17 minutes apart, eventually caused both buildings to collapse.

Shortly after the second tower was hit, the third hijacked plane crashed into the Pentagon, the headquarters of the Department of Defense in Arlington, Virginia. Another attack — likely intended for Washington, D.C. — was thwarted when the passengers of a fourth plane fought back against their hijackers, causing the aircraft to crash near Shanksville, Pennsylvania. In total, 2,977 people were killed across the different attacks, according to the 9/11 Memorial and Museum.

NASA astronaut and ISS commander Frank Culbertson — the only American not on Earth at the time of the attacks — passed over New York City shortly after being told about what was happening back home. He photographed the thick plume of smoke blowing away from Manhattan, at an altitude of roughly 250 miles (400 kilometers) above Earth's surface.

If you look closely, you may be able to see what Culbertson described as an "odd bloom" around the base of the column of smoke rising from the towers. This is likely a sign that the image was captured "around the time of, or shortly after, the collapse of the second tower," Culbertson said.

Culbertson wrote several letters in the days following the attacks, sharing his unique perspective of the events. "It's horrible to see smoke pouring from wounds in your own country from such a fantastic vantage point," Culbertson wrote on Sept. 13. "The dichotomy of being on a spacecraft dedicated to improving life on the earth and watching life being destroyed by such willful, terrible acts is jolting to the psyche."

While in space, Culbertson learned that the pilot of the plane that was later hijacked and crashed into the Pentagon was his former flight school classmate Charles "Chic" Burlingame. When the ISS later passed over the Pentagon, the astronauts could see the large gash in the side of the building where the third plane had crashed. "Tears don't flow the same in space," Culbertson wrote while discussing his friend.

In 2017, Culbertson revealed that there was another striking thing he and the rest of his crew noticed in the wake of the attacks, according to Live Science's sister site Space.com. "One of the most startling effects was that within about two orbits, all of the contrails that are normally crisscrossing the United States had disappeared because they had grounded all the airplanes," he said.

However, there was one exception. The astronauts noticed a single contrail moving eastward across the Midwest. "That was Air Force One headed back to D.C. with President Bush," Culbertson said. It was a "very sobering" sight, he added.

See more Earth from space

When Blue Origin's New Glenn rocket suddenly blew apart on a Florida launchpad earlier this year, it sent sound waves racing more than 1,000 miles (1,600 kilometers) across the U.S., new data reveals. While imperceptible to human ears, the subtle vibrations have helped researchers analyze the blast in surprising detail.

New Glenn is the largest and most powerful of Blue Origin's commercial rockets. It stands at 320 feet (98 meters) tall, roughly the same size as NASA's Space Launch System (most recently used during the Artemis II mission), and is designed to compete with SpaceX's supersized Starship rockets. New Glenn has launched into space three times: first in January 2025; then again in November 2025, when it launched a pair of NASA spacecraft to Mars; and finally in April this year, when it reached space but failed to deploy a giant communication satellite. During the second launch, Blue Origin successfully landed the rocket's reusable booster on Earth, making it the second company to achieve this feat, after SpaceX.

But on May 29, during a static "hotfire test" at Cape Canaveral Space Force Station, shortly before New Glenn's planned fourth launch, the rocket's booster violently exploded without warning. The blast shot bits of flaming debris into the air and unleashed a massive mushroom cloud that briefly lit up the night sky. On Aug. 5, Blue Origin revealed that a faulty oxygen valve likely caused the explosion, according to Live Science's sister site Space.com. (The company has not attempted to launch another New Glenn rocket since.)

The fiery failure is believed to be one of the most powerful prelaunch explosions ever seen. The damage caused to the launchpad alone could take at least a year to fix, according to Ars Technica. This not only affects Blue Origin's ability to launch rockets but could also delay NASA's proposed moon base, which will rely on New Glenn to launch some of its components.

Nobody was hurt by the explosion. But thousands of locals reported hearing a thunderous boom as they were hit with the resulting shockwave, which reached up to 135 miles (217 kilometers) from the launchpad, Florida Today previously reported. However, in terms of the sound produced by this event, this was just the tip of the iceberg.

In a new study, published Aug. 12 in the journal The Seismic Record, researchers analyzed data from special listening stations across the U.S. for signs of infrasound — ultra-low-frequency sound below the range of human hearing — that coincided with the blast. At least 36 stations picked up infrasound signals from the explosion, the farthest of which was located in northeast Texas, about 1,046 miles (1,684 km) from Cape Canaveral Space Force Station.

Detecting such distant low-frequency sound waves not only highlights the scale of the blast but also provided researchers with "a very rare opportunity to study [the] large real-world energetic event" in more detail, study first author Elizabeth Silber, a physicist and planetary scientist at the Sandia National Laboratories in Albuquerque, New Mexico, wrote in a statement.

Based on the frequency and travel distance of the sound waves, the researchers estimated that the explosion had the equivalent power of 0.131 kilotons (144 U.S. tons) of TNT, which is slightly higher than the initial blast that destroyed the nuclear reactor at Chornobyl in 1986, according to a 2009 study.

The team also worked out how much of the rocket's fuel was consumed in the initial explosion. Although the exact amount of fuel in the booster is unknown, they estimate that between 3% and 6% of the rocket’s cryogenic propellant was used up in the initial blast. This may seem low, especially considering the size of the fireball, but it lies within the expected range, researchers said.

"In a large propellant accident, the fuel and oxidizer do not necessarily mix and react all at once," Silber said. "Some material can contribute to the initial blast, while other material can burn more gradually in the fireball and the plume."

The researchers believe that infrasound is an underutilized and potentially valuable tool for tracking spacecraft accidents or other large explosions across the globe.

The same team has also previously used the low-frequency sound waves to track meteors and spacecraft as they enter Earth's atmosphere, including the return capsule of NASA's OSIRIS-REx mission in 2023.

This striking satellite snap shows a series of ghostly green lakes that merged into a single murky entity after several years of unusual weather in the Australian outback.

The entwined lakes are located in Barkly Tableland, an area within Australia's Northern Territory, which lies between the states of Queensland, South Australia and Western Australia. The largest section of the conglomerate is Tarrabool Lake (on the left side of the photo), which stretches around 55 miles (90 kilometers) across at its widest point. It is dark green due to the dense vegetation and algae in the water.

The smaller half of the merged lakes (on the right side of the image) is made up of three lakes: Lake Sylvester, Lake Corella and Lake Deburgh. This section has a paler and chalkier hue due to high levels of suspended sediment. This is likely because the lakes have overflowed and mixed together, whipping up the dust and topsoil that once surrounded them. (Several other, smaller lakes of various sizes and shades of green can also be seen throughout the image.)

All of these lakes are ephemeral, meaning they have no constant inflow or outflow of water, much like most of Australia's other lakes. As a result, they almost completely dry out during prolonged periods of sunny weather, as high temperatures cause the water inside them to evaporate, and then reappear as heavy rainfall refills the basins.

However, across the two years prior to this image, there was so much rain that the lakes never dried out. Instead, they continued to grow year over year, as you can see from additional satellite imagery (see below), which shows the same area between 2022 and 2024.

The Northern Territory's rainy season lasts between October and April. Both the 2022-2023 and 2023-2024 rainy seasons, which preceded the 2024 satellite photos, were ranked among the top 10 wettest since 1990, according to NASA's Earth Observatory, which released these images.

Although this is extreme, it is not that surprising, considering that annual rainfall in the Barkly Tableland rose by around 14% between 1989 and 2018, according to a report from the Australian Bureau of Meteorology. This is likely due to the effects of human-caused climate change.

On top of the general increase in rainfall, Tropical Cyclone Megan dumped a massive amount of rain on the region in March 2024. The resulting flash flooding was so great that fish were seen swimming across a nearby road, Australia's ABC News previously reported.

In the winter, Tarrabool Lake and Lake Sylvester are important breeding sites for birds, including the straw-necked ibis (Threskiornis spinicollis) and the Australian pelican (Pelecanus conspicillatus), and BirdLife International lists both lakes as important bird areas. At its fullest, Tarrabool Lake also floods the surrounding Eva Downs Swamp system, creating Australia's largest wooded swamp.

See more Earth from space