This Asteroid Will Come Eerily Close to Earth on Halloween
Yes, it’s true: a rather not-so-tiny near-Earth
asteroid SKULL-SHAPED ZOMBIE COMET (see below) 2015 TB145 will make a relatively close pass by our dear planet Earth on October 31, aka Halloween — the day when certain beliefs profess that the veil separating the worlds of the living and the dead is at its thinnest, allowing spiritual and even physical interaction to occur between both.
Of course there is no scientific evidence that the latter is at all true but it makes for good scary stories around the light of a campfire. And as the first-world campfires of today are the stark lights of computer monitors and smartphone screens, some are trying to weave scary stories about the passing of this asteroid as well. Should you be afraid? Certainly not. (But there is a cautionary tale to be told.)
While there isn’t anything to be concerned about from 2015 TB145, it will pass relatively near to Earth, coming as close as about 500,000 kilometers (310,000 miles) at 17:05 UTC on Oct. 31.* And it is of considerable size — somewhere in the range of 290-650 meters (950-2,133 feet) in diameter, which isn’t enormous for asteroids BUT you certainly wouldn’t want it landing in your back yard (especially considering that it’s traveling an “unusually high” relative velocity of almost 35 km/s… that’s over 78,000 mph!)
If you’re thinking that seems like a big size range for an object like this to “possibly” be, there’s a reason (and thus the cautionary tale) — 2015 TB145 was just discovered this month.
The NEO 2015 TB145 was identified on Oct. 10, 2015 via the PanSTARRS I (Panoramic Survey Telescope & Rapid Response System) survey telescope, located atop Mount Haleakala in Hawaii. The goal of PanSTARRS is specifically to locate objects like this, so it accomplished exactly what it should. But it also reminds us that there are still as-yet undiscovered objects out there orbiting the Sun in the vicinity of our planet, and it’s important that we maintain vigilance and continue supporting global efforts to find and study them.
As it passes Earth 2015 TB145 will be observed with some of the best radar telescopes on the planet — NASA’s DSS-13 at Goldstone, California and NRAO’s Green Bank Telescope in West Virginia (and possibly also with the Arecibo Observatory in Puerto Rico.) Because TB145 is so dark (absolute magnitude currently listed as 19.8) optical observations won’t reveal much, but radar can help scientists “see” the asteroid and determine its size, shape, and rotation and better plot out its orbital trajectory into the future…especially where it concerns its encounters with our planet.
According to a news statement on NASA’s Goldstone site, “The flyby presents a truly outstanding scientific opportunity to study the physical properties of this object.”
(Who knows… they may find that it has a little moon of its own. There are plenty of asteroids that do.)
NASA won’t be the only ones watching this object’s pass either — plenty of amateur astronomers around the world will have their ‘scopes set on 2015 TB145’s path, especially in the Middle East where it will still be dark during its closest approach. Find out how to view TB145 here, and you can watch a live broadcast of the viewing on the Slooh site here starting at 12:30 p.m. ET (16:30 UTC) on Oct. 31.
There is some significance to this pass too: this will be the closest known approach by an object this large until the 800-meter asteroid 1999 AN10 approaches at about 1 lunar distance in August 2027. (Source)
And, based on TB145’s orbit and high velocity, it’s suspected that it might even actually be a comet.
“The asteroid’s orbit is very oblong with a high inclination to below the plane of the solar system,” said Lance Benner of JPL, who leads NASA’s asteroid radar research program. “Such a unique orbit, along with its high encounter velocity — about 35 kilometers or 22 miles per second — raises the question of whether it may be some type of comet. If so, then this would be the first time that the Goldstone radar has imaged a comet from such a close distance.”
So while NASA isn’t spooked by 2015 TB145 (and you shouldn’t be either) we should all still be aware that we’re certainly not the only ones traveling on this road around the Sun… there’s always the chance of running into the occasional traffic. It’s important that we spot them — especially the big ones — first.
“We as humans are living on a planet that’s in a sort of celestial shooting gallery, and there are lots of objects out in space, primarily asteroids, that come close and do hit us from time to time.”
— David Morrison, Senior Scientist at NASA Ames Research Laboratory (Ret.)
*2015 TB145 will also pass closely by our Moon, coming within about two-thirds that distance two and a half hours prior.
UPDATE 10/30: radar observations from the Arecibo Observatory have been used to create an image of the quite-dark 2015 TB145 and, if it wasn’t spooky enough that the asteroid is passing on Halloween, it even bears an uncanny resemblance to a giant skull and it might really be a comet — a dead one. Read more here.
Just for fun (whee!) I ran some of the known values for 2015 TB145 through an online impact calculator developed by Dr. Andrew Scott at the University of South Wales. Assuming that TB145 is composed of mainly porous rock (if it’s a comet it could even be less dense; if a stony/iron asteroid more) then a totally direct strike on Earth at a 90º angle in, say, New York City would leave a crater 9,767 feet (2,977 meters) wide and 2,080 feet (634 m) deep — bigger than Barringer Crater in Flagstaff, AZ. Luckily impacts of this magnitude are 1-in-75,000-plus year events (and don’t specifically target major cities!) But needless to say it would be a very bad day in the Big Apple.