June 30 marked 110 years since the largest collision of an asteroid with Earth in modern history. Today, astronomers are readying a new telescope designed to protect the Earth from future threats from space.
The Large Synoptic Survey Telescope (LSST), currently under construction in Chile, is designed to locate and track large asteroids which could threaten our home planet.
“The scars of these past collisions are prominent on the moon, but the Earth also bears the marks of such impacts. Chicxulub crater on Mexico’s Yucatan Peninsula was created by the Chicxulub asteroid that drove the dinosaurs to extinction. The Barringer Crater in Arizona is just 50,000 years old. The question is not if a dangerously large asteroid will collide with the Earth, but when?” wrote Michael Lund of the Department of Physics and Astronomy at Vanderbilt University.
In 1908, a massive body impacted with our planet near the Podkamennaya Tunguska River in Siberia. Although no one was killed by the blast, the event levelled trees over an area of nearly 2,000 square kilometres (770 square miles), and people standing 65 kilometers (40 miles) away were knocked off their feet.
How much damage such a collision would cause is based, in part, on the size of the object impacting the Earth. Asteroids the size of cars will usually burn up in the atmosphere without causing significant damage. Larger ones can explode above the ground, creating enough heat to produce sunburn-like damage to people unlikely enough to be caught near the blast. Objects the size of houses can explode with the force of a small nuclear bomb, devastating a city. If an asteroid is the size of a skyscraper, it could destroy a large city, like New York or Los Angeles. If Earth were to be hit by an object half-a-mile across, it could obliterate an area the size of Virginia, resulting in a crater 100 miles in diameter. The effects of such a blast could include a dust cloud capable of affecting crops around the world. An asteroid the size of a large mountain, like the one that ended the reign of the dinosaurs 66 million years ago, could wipe out most life on Earth.
In 2013, an asteroid exploded over the city of Chelyabinsk, Russia, with a blast 20 to 30 times greater than the atomic bombs that destroyed the cities of Hiroshima and Nagasaki at the end of the Second World War. Approximately 1,100 people were injured during that event, and over 7,000 buildings were damaged.
Researchers are still uncertain exactly what kind of body was responsible for the 1908 event in Russia, although it was likely an Apollo-class asteroid. Astronomers know of more than 1,600 of these bodies, each over 140 meters (450 feet) in diameter, which cross the orbit of Earth. Astronomers hope the LSST will find up to 65 percent of all potentially hazardous asteroids in our solar system.
Every June 30 is now recognized as International Asteroid Day to mark the anniversary of the blast which occurred at Tunguska.