A decent-sized asteroid, the 1,100-foot-wide Apophis, will pass so close to Earth it'll be visible in the sky from certain places.

Yet the internet — awash with clickbait — likes to incessantly warn of incoming threats with misleading headlines like "Asteroid heading our way day before presidential election," "Should you be worried about the 'potentially hazardous' asteroid passing by Earth today?," and "Massive asteroid will swing by Earth after Valentine's Day." .

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 (PHOs) and any potential for impact.".

Though sensationalist media stories about incoming asteroids are many, NASA hasn't ever sounded the alarm about a dangerous asteroid bound to impact Earth, or a very worrisome approach. .

"We have never actually issued a warning," said Johnson.

Yet this planetary defense office exists because, at some point, a significant impact is inevitable (unless we build technologies to successfully deflect threatening objects.) On June 30, 1908, an asteroid, some 120 feet (37 meters) wide entered the atmosphere and then blew up over forested Siberia.

Using big telescopes, NASA's Center for Near Earth Object Studies looks for asteroids and comets (called near earth objects, or NEOs) that "enter Earth's neighborhood," meaning coming within 45 million kilometers (some 28 million miles) of Earth's orbit.

The rocks of particular concern are labeled "potentially hazardous asteroids." This means they come within about five million miles of Earth.

There are generally two types of warnings: notification of a very close encounter and notification of a potential impact.

For either of these, you'll know they're legitimate because "NASA has actually said something about it," said Johnson.

A close encounter means a space rock isn't going to strike Earth, but NASA thinks it's still deserving of the public's attention, explained Johnson.

If NASA detects a possible impact — something larger than around 30 feet across (10 meters) with a greater than one percent chance of hitting Earth — things get serious.

"We can advise leadership as to what might be faced should the asteroid impact the planet."

In stark contrast, a larger asteroid (some 100 to 170 feet wide) survived the atmospheric plummet and left a 600-foot-deep crater in Arizona 50,000 years ago

"A similar-size impact event today could destroy a city the size of Kansas City," David Kring, an impact expert at the Lunar and Planetary Institute, told NASA this year

If it should pass that a sizable asteroid is destined for Earth, NASA astronomers and orbital modelers will run thousands of simulations, somewhat similar to weather or hurricane prediction, to forecast where it's likely to land