Ancient impact crater 'with legs' spotted in Australian desert by NASA satellite

NASA has released a satellite image showing a mysterious structure hidden in the Australian desert.

The agency's Landsat 9 recently passed over the Kimberley region of Western Australia, capturing what it called 'an impact structure with legs.'

While the structure may look otherworldly, NASA noted it is aptly named Spider Crater, a meteorite impact followed by hundreds of millions of years of erosion.

Close to the ground, sparse patches of green vegetation appear throughout the image, contrasting with the red rocks. 

Vegetation is especially thick along the banks of the thin stream that meanders diagonally across the crater. 

Spider Crater’s unusual shape left geologists puzzled over its origins for years, until evidence emerged in the 1970s.

Researchers identified grooved, cone-shaped fractures in rock, telltale signs of a meteorite or asteroid impact.

Severely distorted layers of sedimentary rock strengthened the case, revealing evidence of the immense forces unleashed when an object from space slammed into Earth. 

The oval-shaped impact structure is eight by seven miles, with a spiderlike central portion measuring 2.5 miles across. 

But while scientists have established what created Spider Crater, exactly when it formed remains a mystery. 

Estimates place the collision between 600 million and 900 million years ago.

For years after its discovery in the 1950s, the crater baffled scientists, who struggled to explain how its unusual shape had formed.

The site’s rugged terrain and remote location make it difficult to reach, with its distinctive pattern best seen from the air or in satellite images.

Some experts suggested the strange formation had a volcanic origin. But a closer look revealed signs of a far more violent past.

Geologists found fractures, known as shatter cones, scattered across Spider Crater’s central dome. These distinctive cracks form only when intense shock waves tear through rock, providing telltale evidence of an impact.

Laboratory analysis of shocked quartz and zircon crystals in the sandstone has given researchers further clues that could help reconstruct the angle at which the meteorite struck.

Australia is also home to the world's oldest impact crater.

Scientists had long suspected that the North Pole Dome in Western Australia's Pilbara region was the site of an ancient catastrophe.

In July, researchers uncovered the first rock–solid evidence that provides an exact date for the impact.

Using advanced mineral dating techniques, they show that the crater was formed when a space rock smashed into Earth 3.02 billion years ago.

While billions of years of erosion have wiped away much of the evidence, this impact was substantial enough to leave a lasting legacy on Earth.

Lead author Professor Chris Kirkland told the Daily Mail that this meteor could have been a 'kilometre–scale' object, although its precise size is impossible to determine.

He said: 'At North Pole Dome, the impact appears to have generated a long–lived fractured system that was later reused by fluids.

'On the early Earth, that kind of process could have influenced chemical exchange between rocks and an early ocean, causing mineral alteration and potentially modifying the environments available for microbial life.'

The key piece of evidence was zircon, an extraordinarily resilient mineral that can hold its shape for billions of years.

When the researchers took samples from the rocks around North Pole Dome, they found that some zircon crystals had strange branching or 'skeletal' shapes.

Professor Kirkland believes that these are 'impact–modified crystals' formed when old zircon in the rocks was disrupted and partially recrystallised by the intense heat of an impact.

Critically, they were also able to date the formation of these crystals to an event around three billion years ago.