For some of my friends and family, somewhere between the youthful excitement at the prospect of costumes and candy and the responsibilities of adulthood, Halloween went from innocent fun to an evil rite. The objections to the quasi-holiday come almost exclusively from where they always do: Right-wing ideologues wrapped in the flag and wearing a cross. Satan is a powerful demigod, you see, so powerful that its one true opportunity to overthrow the good gods and rule mankind from Hell is mysteriously dependent on 9-year-olds donning Avengers costumes, thus allowing the Prince of Darkness access to this mortal realm by way of Twizzlers and M&M's.
Be that as it may, there is an interesting threat of sorts heading our way. It poses no real danger, but it will be a cosmic close call. And if it did strike with its full force, we'd definitely enjoy at least a taste of what Armageddon might be like. How would the Imperial USA, indeed the whole world, respond to such a trick? Join us below, guys and ghouls ...
253 Mathilde, a C-type asteroid measuring about 50 kilometers (30 mi) across, covered in craters half that size. This one is far larger than TB 145. Photograph taken in 1997 by the NEAR Shoemaker probe
The space rock is known by the designation
TB 145 and it will make its closest pass next Saturday, on Halloween. TB 145 is estimated to be roughly 500 meters or about 1500 feet in diameter, although how its shaped and precisely how big it is in any direction is unknown. Relative to Earth it's moving at over 20 miles per second, or about three times faster than the Apollo command module at maximum velocity just prior to re-entry. Assuming an average rocky density of 3000 kilograms per cubic meter, it would do some serious damage if it were to strike the surface.
Using this impact effects calculator, we can gauge how bad it could be. Just the fireball moving through the sky would be many times larger and brighter than the fiercest summer sun. One glance and you would be blind for life. It would be so hot and so bright that anyone within 50 miles would be burnt to a crisp, and clothing would ignite. If it went on to hit land, the resulting glowing crater would be more than five miles wide. Ejecta would slam down like red hot bowling balls for dozens of miles around, lighting everything on fire that survived the initial fireball and subsequent artillery barrage. A blast wave that could knock down trees and buildings would scour the surface for a hundred miles in either direction. If it hit shallow sea, all the above would still happen, and then a tsunami as high as 200 feet would slam into coastlines the world over.
Watching movies about impact threats, it seems simply blowing them to tiny pieces with large thermonuclear devices would be relatively easy. But it actually doesn't work that way because, in space, no one can hear you scream! One of the things that makes a nuke so destructive on the Earth's surface is the shockwave. It's the supersonic blast of hot, moving air that blows over buildings and lights everything close by on fire. Without an atmosphere to conduct it, there is no blast wave and the power of the bomb is greatly reduced. Even if it did work like it does on the big screen, it would only amplify our problems by turning one largish impact devastating many square miles into dozens or hundreds of smaller ones all over the planet.
The best way to intervene would probably be what astronomers call a gravity tractor. This method involves putting a spacecraft near the object and moving it slowly, incrementally, over many months by the power of mutual gravitational attraction until the asteroid is no longer on a collision course. But that method only has a chance if the object is seen years in advance. TB 145 was first seen a few weeks ago.
Which brings up a good question: How would our political system react to such a threat? Given past performance and the current crop of GOP frontrunners, there's a real possibility they might dismiss it. Trump and Carson in particular might well call it a NASA hoax, or at least insist the U.S. not get involved in shouldering the cost to save any undeserving Third World residents who might be in the crosshairs.
In reality, no one need worry this Halloween. This asteroid won't get inside the orbit of the moon. It's so small and it will pass so far away that you won't be able to see it, even with a large pair of binoculars. Observing this bad boy will be the purview of large telescopes in proper observatories run by professional astronomers. Even then it will be a point of light at best. So if you want to watch what they see, check out the online Virtual Telescope here!