Twenty years of planetary defense

On March 11, 1998, asteroid astronomers around the world received an ominous message: new observational data on the recently discovered asteroid 1997 XF11 suggested there was a chance that the half-mile-wide (nearly one kilometer) ...

Scanning in the fourth dimension

Three-dimensional (3-D) computed tomography is a widely used technology that visualizes an object's external and internal structure by assembling a series of two-dimensional images taken sequentially across or around it. ...

Unconfirmed near-Earth objects

Near-Earth objects (NEOs) are small solar system bodies whose orbits sometimes bring them close to the Earth, potentially threatening a collision. NEOs are tracers of the composition, dynamics and environmental conditions ...

Image: Tunguska devastation

Fallen trees at Tunguska, Imperial Russia, seen in 1929, 15 km from epicentre of aerial blast site, caused by explosion of a meteor in 1908 (Photo N. A. Setrukov, 1928).

What it takes to discover small rocks in space

Once every month, on average, somewhere on Earth a fireball appears out of nowhere and for mere seconds, casts a blinding flash across the sky before it blows up in a thunderous explosion. It happened last Saturday over southern ...

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