The deadly asteroid Apophis is safely passing by Earth today, more than 9 million miles (14.5 million kilometers) from our home planet. Next time we won't be so lucky. On April 13, 2029, Apophis will come so close that it may destroy satellites in orbit.
The European Space Agency's Herschel space observatory has acquired new images of the asteroid and their new data is conclusive.
First, it's much bigger than NASA's previous estimation. According to the new images, this rocky beast has a diamater of 1,066 foot (325 meters), with a margin of error of ±49 feet (±15 meters). According to team leader Thomas Müller of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, "the 20% increase in diameter, from 270 to 325 m, translates into a 75% increase in our estimates of the asteroid's volume or mass."
What that means is if it hits Earth, its destructive power will be much higher than what scientists originally expected. Based on previous data, NASA estimated an impact of 510 megatons for Apophis. That's more than two times the energy released by the Krakatoa eruption of 1883, an event that changed Earth's global climate for five years.
While scientists have not released a new estimate, the 75 percent mass increase may bring its power closer to NASA's earlier estimations of 880 megatons—about 17 Tsars, the biggest nuclear bomb ever created.
The good news (!) is that Apophis is still small enough not to kill us all, but it can disrupt life on the planet for a few decades (click here to watch Neil DeGrasse talking about the effects of an Apophis impact in California). For comparison, the Chicxulub asteroid released about 100,000,000 megatons when it triggered the mass extinction event that supposedly wiped out the dinosaurs.
RELATED READING: Watch this video to see what will happen if a truly gigantic asteroid hits Earth.
In 2029 we'll be safe from Apophis mayhem too. The asteroid will not hit Earth then, say astronomers, but it "will pass within 36,000 kilometers of Earth's surface, closer even than the orbits of geostationary satellites."
This means that, while our pale blue dot would be spared, our highly populated constellation of satellites may suffer some casualties. Which will be bad if it happens, but not as bad as NASA's initial estimation of 2.7% chance of impact.
Nobody knows exactly if a satellite collision may occur. Space is awfully big, but there are plenty of satellites out there. Enough that it's not crazy to think that some of them may be wiped out as we watch Apophis marching through the night sky.
Scientists can't tell what will happen in the following pass, in 2036. According to the latest analysis, there is a 1 in 250,000 probability of impact. It's extremely low, but still higher than the odds of being hit by lightning. That's why the Russians are considering a mission to deflect it—with Bruce Willis' character played by Sean Connery as Captain Marko Ramius. [ESA]