I set a snare and captured my asteroid this morning. 2012 KT42, a space rock estimated at 10-30 feet across, blew by Earth earlier today at a distance of only 8,700 miles, well below the altitude of geosynchronous satellites we rely on for communications around the globe.
Although it sounds Hollywood-movie-scary, the chance of a random asteroid hitting a satellite is extremely remote. If one were to be hit, the smack-down would far more likely come from one of the thousands of much smaller and more common meteoroids that occasionally arrive on Earth as meteorites.
I’ve seen near-Earth asteroids before but nothing like 2012 KT42. Sure they all look like moving stars, but this one took my breath away. In 40 years of sky watching, I’ve never witnessed anything beyond Earth move faster. My snare consisted of two parts: a chart with two possible paths and passage times and a telescope. After pointing the scope at where 2012 KT42 was predicted to arrive at 1:29 a.m. I sat and waited.
The glowing numbers on my watch dial indicated 1:23 a.m., then 1:26 and 1:28 a.m. No asteroid yet. But seconds later, there it was – a “star” moving like a flung rock entered the field of view stage right (east) and never slowed down. Interestingly, the asteroid showed up a minute early, possible due to a change in its orbit by Earth’s gravity.
I timed the asteroid’s passage. At 1:30 it moved the span of two full moons (one degree) in one minute. By 1:53 a.m., its speed had doubled to one degree every 30 seconds. At 64x in the scope, 2012 KT42 moved about as fast as the space station does when viewed with the naked eye.
My particular telescope and eyepiece combination gave me a field of view of one degree, so you can imagine how often I had to push the scope to keep track of the asteroid. If I’d taken my eye away from the eyepiece for a minute, I would have lost it for good.
While tracking the speedy missile, I happened to look up toward my garage, and it occurred to me that if it were possible to lasso 2012 KT42 and bring it down to Earth, I could park it there with room to spare.
With that image in mind, I returned to the eyepiece and tried to comprehend seeing something that small move so quickly across the sky. A few miles closer and it would be a shower of meteorites.
One other interesting aspect of watching the flyby was the change in the asteroid’s brightness. It was never constant for long. At 1:30 a.m. it varied between 12th and 13th magnitude in an irregular way; by 1:50 a.m. it was varied from about 11 to 12th. I assume this was because it had an irregular shape and was rotating. For the sake of explanation, let’s assume 2012 KT42 were shaped like a cigar.When brightest, we’d be seeing the cigar broadside with a maximum amount of surface exposed to sunlight; when faintest we’d see only the butt of the cigar. The brightness variations may also have been due to the changing angle of sunlight on 2012 KT42 as it zoomed across the sky.
Nothing escapes the clouds. Not even asteroids. By 1:53 a.m. the morning’s clear sky quickly turned overcast and I finally lost the asteroid as it flitted between ribbons of white mist. It was a wonderful ride, those 25 minutes.