From orbit, it looks like a huge pale spider sprawled across the rugged red landscape of northern Western Australia, with a dark body and long, bent legs. The image, captured by Landsat 9 on Sept. 20 and published by NASA Earth Observatory, shows a geological feature known as Spider Crater.

The spider is not alive and is not a drawing — it is rock. It is the eroded remnant of an ancient collision between Earth and an object from space, one so old that most of the original crater has worn away.

The central spider shape is about 4 kilometers (2.5 miles) across, while the full oval impact structure measures about 13 by 11 kilometers (8 by 7 miles). It sits in the Kimberley region, one of the most remote parts of Australia.

Legs Made of Hard Sandstone

The legs are the most striking part of the picture, and they have a simple explanation. They are ridges of light-colored sandstone that resisted erosion while the surrounding rock layers wore away, NASA said.

The spider's body is thought to be what remains of the crater's central uplift. When a large object strikes the ground, the crater floor rebounds upward after the shock wave passes, much like a drop of water splashing back up from a puddle. Over hundreds of millions of years, erosion stripped away the rest of the crater and left this tougher, uplifted core exposed.

Geologists have studied that core in detail. A 2013 study by geologists Kenkmann and Poelchau, cited by NASA, focused on the central uplift itself, while an earlier 2005 paper by Abels in the Australian Journal of Earth Sciences described the impact structure on the Kimberley Plateau as a whole. NASA's account of the crater draws on both, along with Space Shuttle radar imaging.

The image was taken by the Operational Land Imager on Landsat 9, a joint NASA and U.S. Geological Survey satellite that photographs the entire Earth's land surface on a regular cycle. Landsat's long record, which stretches back to 1972, is widely used to track changes in farms, forests, cities, and coastlines, but it also reveals ancient features like this one that are hard to see from the ground.

The Clues That Ruled Out a Volcano

Not every circular scar on Earth is an impact crater — and scientists once debated this one. Some earlier researchers proposed a volcanic origin, according to NASA.

The decisive evidence came from the rocks themselves. Geologists found shatter cones, fan-shaped fractures that form only under the intense shock waves of an impact, and they are especially common in the central dome. Laboratory analysis of shocked quartz and zircon crystals from the sandstone has also helped researchers reconstruct the angle at which the impactor struck.

A 2021 study in Meteoritics and Planetary Science by M.A. Cox and colleagues, titled Asymmetric shock deformation at the Spider impact structure, examined that uneven shock damage. Research on the structure has long suggested the object struck at a low angle rather than straight down, which fits the elongated, oval outline seen from space.

Space Shuttle radar imaged the site in research published in 2002, and NASA has featured it before, including an earlier Earth Observatory close-up. The new Landsat view offers a sharp look at how its shape stands out from the surrounding plateau.

Older Than Most Life on Land

The impact happened long before dinosaurs or even complex animals. Its exact date is uncertain, but estimates based on the regional rocks place it between about 900 million and 600 million years ago, in the late Precambrian, NASA said.

At that time, life on Earth was almost entirely microbial and marine. The landscape that the impactor struck would have looked nothing like today's Kimberley, and the rock layers that now form the spider's legs lay buried beneath the surface.

Dating ancient craters is difficult because erosion removes the material scientists would normally use, and impacts can reset some geological clocks while leaving others untouched. That is why researchers can only give a broad range for Spider Crater rather than a precise age.

A Window Into Earth's Impact History

Earth has been hit by space objects throughout its history, but weather, water, plate tectonics and plant life erase most of the evidence. Old, stable continental crust and dry climates, like those in much of Australia, give ancient impact scars a better chance of surviving long enough to be recognized.

Large impacts typically form central peaks or uplifts like the one at Spider Crater, a process described in the Lunar and Planetary Institute's impact cratering resources cited by NASA. Similar features are visible on the Moon and Mars, where the lack of weathering has preserved them far better.

For U.S. readers, the closest comparison is Meteor Crater in Arizona, a much younger and simpler bowl-shaped crater about 50,000 years old. Spider Crater shows what a larger impact structure can look like after hundreds of millions of years of erosion have peeled away everything except its hardest rocks.

There is no hazard associated with Spider Crater today, and it says nothing about the odds of future impacts. Tracking near-Earth objects is the job of NASA's planetary defense program, which is separate from the Earth-imaging work that produced this picture.

The image is a reminder that some of Earth's most dramatic history is written in landscapes that are easiest to read from space. Readers can explore this and other features through NASA's free EO Explorer and Landsat image archives.

What Readers Want to Know

What is the spider shape in Western Australia?

It is Spider Crater, the eroded remains of an ancient impact structure in the Kimberley region, photographed by Landsat 9 on Sept. 20.

Why does it look like a spider?

The dark body is the remnant of the crater's central uplift, and the legs are ridges of hard sandstone that resisted erosion.

How big is Spider Crater?

The spider-shaped center is about 2.5 miles across, and the full oval structure is about 8 by 7 miles.

How old is it?

Estimates place the impact between about 900 million and 600 million years ago, in the late Precambrian.

How do scientists know it was an impact?

Geologists found shatter cones and shocked quartz and zircon crystals, features that form only under impact shock waves.

Is there any danger from it today?

No. It is an ancient geological feature and has no bearing on future impact risk.