This story was originally published in June of 2021.
Something will happen on April 13, 2029, which is Friday the 13th.
The 1,100-foot-wide Apophis will pass so close to Earth that it will be visible in the sky. The giant rock will not hit our planet. It will pass less than 20,000 miles from the surface, which is closer to the most prized weather satellites in the United States.
Big impacts are at once terrible threats to our lives and potentially the habitability of many species, but they are also extremely rare and irregular events. The internet likes to warn of incoming threats with misleading headlines like "Asteroid heading our way day before presidential election"
Many of the objects pass millions of miles away, so these stories are not about real danger. The stories are about sensationalism.
Lindley Johnson, NASA's Planetary Defense Officer, understands what will happen when a big one comes. If a serious threat to either a region on Earth, a large swathe of Earth, or perhaps the entirety of Earth is truly on its way, you will know about it.
Radar images of Apophis taken in 2012. Credit: NASA/JPL-CalTech
NASA created its Planetary Defense Coordination Office in early 2016 with a mission to provide timely and accurate information to the government, the media, and the public on close approaches to Earth by potentially hazardous objects.
NASA has never sounded the alarm about a dangerous asteroid bound to impact Earth or a very worrisome approach.
Johnson said that they have never issued a warning. They have told the public what asteroids of interest are doing.
"We have never actually issued a warning."
This planetary defense office exists because at some point a significant impact is inevitable unless we build technologies to successfully protect ourselves. On June 30, 1908, a 120 feet wide asteroid blew up over Siberia after entering the atmosphere. The resulting shock mowed down trees. The blast threw a man from his chair, 20 miles away.
It would be a serious event if that blast happened today. There is a chance that we would detect it before it happened.
NASA and other agencies detect larger objects that are more dangerous than the Tunguska rock. Using big telescopes, NASA's Center for Near Earth Object Studies looks for asteroids and comets that enter Earth's neighborhood. The rocks of particular concern are labeled as potentially hazardous asteroids, which means they come within five million miles of Earth. The moon is on average some 238,855 miles away.
A majority of the biggest boys are rocks larger than one kilometer, like the six-mile-wide monster that wiped out the dinosaurs. There are many dangerous rocks. According to NASA, there are two out of three NEOs that have not been found.
The 56-foot (17-meter) rock that exploded over Russia and blew out people's windows is proof that even smaller rocks are still dangerous.
When a threatening rock is detected, what will happen?
The "rubble-pile" asteroid Bennu, which is taller than the Empire State Building, is considered a "potentially hazardous object." Credit: NASA
There are two types of warnings, notification of a very close encounter and notification of a potential impact. For either of these, you will know they are legit because NASA has said something about it.
1. A close encounter.
NASA thinks a space rock is still deserving of the public's attention, even though it isn't going to hit Earth. It could be as small as a rock, or as large as a rock. Other people might spot the close encounter of the rock and then announce the flyby earlier than NASA. That is okay. The agency will take a few hours to verify the results.
The goal is not to be the first to announce something, but to be the ones that provide the best information.
2. There is a potential impact.
If NASA discovers a possible impact larger than 10 meters with a one percent chance of hitting Earth, things will get serious.
The White House, Congress, and government agencies will be given warnings by Johnson's office. The White House will take the lead on new information being released once public warnings have been made. If an impact on U.S. soil were likely, FEMA would have to prepare for a disaster.
NASA will be working on its own. The European Space Agency and the UN-recognized International Asteroid Warning Network will get information from them. Scientists at the IAWN didn't comment, but suggested we speak with NASA's Johnson.
"It becomes a national emergency event."
The White House and other government leadership need to be told that an impact is likely and what it will do. The size and composition of the object are some of the factors that can be considered.
The rock exploded when it traveled tens of thousands of mph through the atmosphere. A larger asteroid survived the atmospheric plummet and left a 600-foot-deep crater in Arizona 50,000 years ago.
The Meteor Crater in Arizona. Credit: USGS
The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) atop Maui surveys the sky and detects new NEOs. Credit: University of Hawaii Institute for Astronomy / Rob Ratkowski via Nasa
NASA will run thousands of simulations to forecast where the asteroid will land if it passes by Earth. Earth is an ocean world, with seas covering 71 percent of the planet, so there's a good chance many rocks won't hit land. It might not matter where a rock lands if it's big enough.
Astronomers are looking for rocks. Each year, NASA discovers about 500 asteroids over 500 feet wide that can cause major regional destruction. As of June 8, 2021, 9,677 of an estimated population of 25,000 have been found.
It's important to complete the survey. Astronomers were surprised by a football field-sized asteroid in 2019. It was within 40,000 miles of Earth.
There is still a lot of stuff out there.
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