What If Recent Near-Miss Asteroid 2011 MD Had Hit the Earth?

News of the relatively close fly-by of asteroid 2011 MD on Monday has generated quite an interest in the hornet's nest of cosmic debris that constantly circles the sun and sometimes finds rather large pieces of space rock hurtling toward the Earth. But what if 2011 MD had hit Earth instead of whipping past 7,600 miles out in space?

The asteroid, according to NASA's Near-Earth Object Program Office at NASA's Jet Propulsion Laboratory in Pasadena Calif., measured some 16 feet by 66 feet, or somewhat larger than a massive tour bus. It was traveling at just over 4 miles per second and passed by Earth at 1:14 p.m. EDT, some 15,000 miles closer than orbiting geosynchronous satellites.

Although seeming somewhat large (a large rock the size of a big tour bus is rather large in comparison to the average human), scientists noted that there was little danger from an impact of an asteroid the size of 2011 MD, according to Space.com. Space rocks of that size generally burn up upon entering the Earth's atmosphere and have a small chance of hitting the Earth, although, if such an event occurred, the result would be that of a small meteorite.

Scientists note that asteroids the size of 2011 MD make close fly-bys of the Earth about every six years.

Fly-by asteroid traffic is more common than many realize. The Near-Earth Object Program regularly tracks around 800 asteroids and comets that have near-Earth trajectories. But some, like 2011 MD, are recent discoveries. In fact, 2011 MD was only discovered on June 22.

As for other hurtling rocks that might or might not ultimately end up on a collision course with the Earth, one came even closer to hitting the Earth in February. Asteroid 2011 CQ1 passed within 3,400 miles of the planet. However, the small object measured only about 3 feet in diameter.

The Earth hasn't been so lucky in the past. It is believed that a large meteorite caused what is commonly referred to as the Tunguska Incident. It is theorized that a rock 120 feet wide blazed across the Siberian sky before plowing up terrain in detonation the equivalent of 185 Hiroshima atomic bombs.

It is also theorized that an asteroid six miles wide hit the Earth 65 million years ago in the Yucatan Peninsula area of Mexico, creating a crater 24 miles deep and 125 miles wide, the impact and detonation precipitating cast-off and debris that heralded the demise of the dinosaurs and a mass die-off of thousands of then extant species.

The Near-Earth Objects Program lists dozens of asteroids and comets that will travel in Earth's vicinity in the next few months.