Halloween In SPAAAAACE!

It is officially the scariest time of the year and what could be scarier than the media misusing a bit of science a ghost story to scare people with?  That’s right, today I’m going to talk about Asteroid 2015 TB145, which some press made a big deal of a couple of years ago, that turns out to be, not all it was cracked up to be.

Get a load of some of these headlines:

  • Grinning-Skull Asteroid Set to Whiz by Earth
  • A Skull-Shaped ‘Dead Comet’ Will Make Halloween Extra Spooky This Year
  • Skull-shaped Halloween close fly-by object is likely a dead comet
  • Spooky ‘skull asteroid’ whizzes past Earth on Halloween
  • NASA Says ‘Great Pumpkin’ Asteroid Will Fly by on Halloween
  • Haunted Again: Skull-Faced ‘Halloween Asteroid’ Returns in 2018
  • Spooky Skull-Shaped Asteroid Will Haunt Earth Again in 2018
  • Skull-shaped asteroid set to miss Halloween [poor fella must be out in the pumpkin patch awaiting the Great Pumpkin]
  • ‘Death Comet’ To Pass Earth Much Farther Away Than In 2015 [‘Death Comet’ is my favorite]

While this space rock may evoke King Kong’s Skull Island, the moon from The Legend of Zelda: Majora’s Mask, or, if you’re an astronomy nerd:

  • The planetary nebula NGC 246 that’s also known as “the Skull Nebula”
  • The star-forming region NGC 2467 which is called “The Skull And Crossbones Nebula”
  • “The Perseus Cluster’s X-Ray Skull,” which I’m claiming for a band name

But Asteroid 2015 TB145 is none of these things. Although, being something in space  it is still interesting.

To begin with, it has a really funky orbit that’s not a simple circle around the Sun like say the planets, but swings closer to the Sun than Mercury, and then way out past Jupiter, which defines it as a Mercury-, Venus-, Earth-, Mars-, and even a Jupiter-crossing asteroid, which is where it spends most of its time.  That elliptical orbit is also somewhat catty-corner to the rest of the big things in the solar system and carries it “below” the orbital plane. This leads scientists to believe Asteroid 2015 TB145 is an extinct (or “dead”, hence the exciting headlines) comet that’s had all of its comety ices and stuff already burned off by the Sun, leaving behind just a rock, which would also suggest it’s been fairly close to the Sun numerous times.  It’s about 2,000 feet (600 meters) in diameter and rotates about once every three or five hours, depending on which source you believe. Vishnu Reddy, a really smart guy at the Planetary Science Institute in Tucson, AZ described it “reflect[ing] about six percent of the light it receives from the sun… that is similar to fresh asphalt, and while here on Earth we think that is pretty dark, it is brighter than a typical comet which reflects only 3 to 5 percent of the light.”  So that’s another reason to think it might be a dead comet.

Asteroid 2015 TB145 was first discovered in 2015 (by the same telescope that found Oumuamua last October – huh!), just 21 days before Halloween that year, which was when it whizzed by within 301,986 miles (486,000 kilometers) of Earth, and only reached “apparent magnitude 10,” or 10m – you’d have needed a lot of luck finding it with an ametuer-level telescope.  That distance is 1.27 lunar distances from Earth, meaning it was further out by a quarter more than the moon is from Earth, which is a pretty good breathing distance; people only start to get a little worried when things pass within one lunar distance, which is about a quarter of a million miles (400000 km).

Keep in mind the Earth is only just near 4,000 miles across or just over over 6000 km – plenty of room, see?  To harp on this further, if the Sun was a beach ball five feet or a meter and a half in diameter and the Earth a blue marble-sized, uh, marble, to scale the Sun would be 590 feet or 180 meters away.  Space is big. Really big. Things can zoom by us all the time, and do, without hitting us because everything in space is so bloody far away.

When Asteroid 2015 TB145 swings by again on November 11th this year it will be as far out as 24 million miles (38 million kilometers) away, or about a quarter the distance between Earth and the Sun – that’s about 103 times further away than the Moon (it will also only be about 19m (it spends most of its time at <20m).  The next chance you’ll get to really feel justified, maybe, in worrying about Asteroid 2015 TB145 is in August 2027, when it will pass by at just 1 lunar distance.  It is an unusually fast-mover though, zipping along at 78,293 mph (126,000 km/h), which admittedly would leave a 6-mile-wide crater if it hit the Earth.

T̶h̢in̡k ̵h͘ap̨py thǫug͘hţs, t̶̢h̀i̷̡͟ǹk̕͜ ̸̀͟h͘a̧p̢py͏̢͜ ̨͡t̡́͜h̨͞ou͞g̷h̸̢t̕͏͢s̴, t͠͏̢͕͚̝̱̬h҉̵̴̥͚̯̪͙̕͞i̵̛̟͍̤͈̯͈̠̺͇̩̝̲͔̳̟̣̩͝͠ͅn̨̡̪̬͔͈͔̹̦͍̦̪̝͍͕̩̤̳ͅk̷͓͈̱̮͕̫̻͍̩̠̟͓̘͈͚̝̪͚̫̀͟ ̶̸̴̰͉̫̮̱̞̭̠̹̀͞ḩ̷̛̤̯͔̱̪̳̰̫͙̟̘̩͘a̸͏͍̝̪̺̥̘̥͉̝̥̫̩̗̟͞p̴̢̗͈͖̦̹͚̠̣̮̯̞̻̮̮̲̭̯̀p̧̧̤͙͉̭̙͕͍͖̲̩̖͚̩͙̕͢ỳ̛̹͇̣͔͙͓̺̱͈̀ͅ ̵̻̻̬̥̘̟̗͙̟̬͉͝͠ͅt̶̵̠͚̩̻̰̺͖̬̝̭̦͇͢͞h̶҉͓̪͎̙̤͖͈̤̞̗͕͉͚͉͓o͏̨̪̦̞̣̤͘͜u̸̧̬͍̮̖̖̘̞̳̜̖̯̙̠͕̗̕͟͡g̵̣͍̥̼̳̞̕h̢̻͕̩͔͔͉͔̮̻͕̘̝͢t̴͚͍̘͓͔̜̜̥̱̪̀́͡s̸̖͍̦͓̜͙̺̫̠…


The first radar images of Asteroid 2015 TB145 came from the National Science Foundation’s 305-meter (1,000-foot) Arecibo Observatory in Puerto Rico and this is where everyone got all excited about this space rock, take a look:


fig. 1:  Well that’s not alarming.

Whoa, it is a skull!  Or is it?  I mean, that’s one grainy blurry picture taken from a gif of about five or six frames, so what about some others?


fig. 2:  It’s a… spinny thing.  [You can see the skull still in the very first frame though].


fig. 3:  I lost my poor meatball.

Well.  I guess it’s not, really – Asteroid 2015 TB145 apparently only has one good side to view it from if you want fear it as a giant skull in space.  And it’s not even a “grinning skull”, I mean, look at the picture, there’s no lower jaw, no teeth to grin!  This is just another example of “pareidolia,” or “a psychological phenomenon in which the mind responds to a stimulus, usually an image or a sound, by perceiving a familiar pattern where none exists.“  This is no more a skull than that Face On Mars is a face.  But people keep sharing that artist’s rendering I shamelessly used for the header photo, which is, shall we say, hopeful at best.  The photos I’ve posted above are literally the best ones we have of this asteroid, so making it look more skull-like in that illustration was just sensationalism.  But hey, anything that gets the public interested in science is probably a good thing, as long as it’s not mere fear-mongering. Which… I guess this kinda was.  But it’s also Halloween which is all about fear-mongering, isn’t it?

If you still insist upon worrying about space rocks bringing death to us all, you can focus on the fact Asteroid 2015 TB145 was only discovered it that 21 days before it swung by, ha ha!  On the other hand, NASA guys are smart cookies who know we need to keep an eye out for potentially dangerous rocks coming our way, so they set up the NASA’s Asteroid Grand Challenge in 2013 and also helped develop some software you can download to help search for them, which probably beats just hiding under your bed or behind the couch: http://asteroids.topcoder.com/

💀   💀   💀

Megara Justice Machine fears the specter of space-death as much as the next guy, but understands something about the vast, yawning distances of nothingness out there in space… which come to think of it, doesn’t really help any.  Still, you could search The Avocado to read some other, less frightful stuff he’s written about astronomy as well, not mention pumpkin spice and cats.  Cats are much nicer to think about, don’t you agree?  Brrr.