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Researchers have discovered never-before-seen types of crystal hidden in tiny grains of perfectly preserved meteorite dust. The dust was left behind by a massive space rock that exploded over Chelyabinsk, Russia, nine years ago.

On Feb. 15, 2013, an asteroid measuring 59 feet (18 meters) across and weighing 12,125 tons (11,000 metric tons) entered Earth’s atmosphere at around 41,600 mph (66,950 km/h). Fortunately, the meteor exploded around 14.5 miles (23.3 kilometers) above the city of Chelyabinsk in southern Russia, showering the surrounding area in tiny meteorites and avoiding a colossal single collision with the surface. Experts at the time described the event as a major wake-up call to the dangers asteroids pose to the planet.

A giant asteroid’s impact is considered the likely cause of the mass extinction of the dinosaurs almost 66 million years ago.

While there is no potential harm from an asteroid on the Earth at present, it is still important to keep our defense system ready in order to prevent catastrophic consequences such as impacts by deflecting trajectories of asteroids if one is ever discovered.

With this aim, NASA launched the Double Asteroid Redirection Test (DART) mission, the world’s first planetary defense test mission, last November. DART is the first-ever mission dedicated to investigating and demonstrating one method of asteroid deflection by changing an asteroid’s motion in space through kinetic impact. In summary, it is to collide with an asteroid and deflect it from its orbit in order to provide valuable information for the development of such a planetary defense system.

One of the largest comets known is approaching our planet on the only trip through the inner solar system it will make during our lifetimes.

Five years ago, the Hubble Space Telescope spotted a large comet at the farthest distance ever, as it was approaching the sun from way out between the orbits of Saturn and Uranus. Now, that giant space snowball is coming in for its closest pass by Earth in just a few weeks.

Comet C/2017 K2 will be at its nearest point to us on its current swing through the inner solar system on July 14. Even at its closest, however, it will still be farther away from us than the average distance between Earth and Mars. This will likely make it difficult to see the comet without at least a small telescope, despite its substantial stature.