Sky Fragments

November 8, 2013

meteor-shower-1833-grangerSkies up along California’s north coast this afternoon makes seeing anything celestial a bit dicey, not there’s any reason specifically, other than more space-rock news, and ‘one strange asteroid:’ The Hubble Space Telescope has discovered a six-tailed asteroid in the asteroid belt between the orbits of Mars and Jupiter. Scientists say they’ve never seen anything like it. Incredibly, the comet-like tails change shape as the asteroid sheds dust. The streams have occurred over several months.

Interesting, but won’t directly impact my life, that’s a telescope scene far, far away in the ether of the solar system — the space-rocks to be concerned about are those humping into close range with our own little planet.
And, not having a shit’s worth of warning, like that Russian meteor last February, undetected until its scorching arrival.

(Illustration found here).

Three reports came out this week on the fireball that blasted the skies over the Urals region of Russia, near the city of Chelyabinsk, which became a disaster movie for a few minutes. A wealth of data came off the event and the reports indicate not only was the incident pretty massive, it could have been worse, and even more-worse, other similar rocks might be headed our way.
Via Discovery:

In the new three papers (two published in the journal Nature and one published in Science), asteroid investigators used the wealth of eyewitness data to determine that as the space rock traveled through the atmosphere, it began to fracture and disintegrate at an altitude of between 45-30 kilometers (28-19 miles).
As it entered the atmosphere, it was traveling at the breakneck speed of 19 kilometers (12 miles) per second.
The main mass of the meteor burst into a cloud of gas, dust and debris at an altitude of 27 kilometers (17 miles) with the energy thirty times that of the atomic bomb that was dropped on the Japanese city of Hiroshima in 1945.
It was at this altitude that the devastating shockwave was generated.
“Luckily, most of the kinetic energy was absorbed by the atmosphere,” said Ji?í Borovi?ka, an asteroid researcher at the Astronomical Institute, at the Academy of Sciences of the Czech Republic in Ond?ejov, near Prague.
“A more solid rock that might have blasted closer to the ground would have caused considerably more damage.”

As Discovery News reported in August, astronomers voiced the possibility that the Chelyabinsk meteoroid may be a part of an asteroid “gang” orbiting the sun on a common trajectory, possibly fragments from another, larger asteroid. According to the three publications, this is cited as a distinct possibility.
According to one of the Nature papers, the modeled orbital trajectory of the Chelyabinsk meteoroid is strikingly similar to the 2 kilometer-wide asteroid (86039) 1999 NC43.
“This is hardly a coincidence,” says Borovi?ka. (In August, however, astronomers had identified “the most probable parent body” for the Chelyabinsk meteor as 150-330 meter-wide asteroid 2011 EO40.

Previously, models predicted the impact frequency of Chelyabinsk-sized meteors to be approximately one every 150 years, but as Brown points out, from the data collected around this Russian meteor event and other small recent atmospheric impacts, this estimate is likely inaccurate.
The upshot from this new research is that, on average, we should expect a Chelyabinsk-sized event once every 25 years at least.

Well, that’s nice to know, ‘at least.’
And also small comfort in the human blind spot (via NBC News):

That Nature paper noted that the Chelyabinsk rock couldn’t have been detected before the blast.
“The Chelyabinsk asteroid was simply too small to be seen at large distances from the Earth with current technology,” Jiri Borovicka of the Astronomical Institute at the Academy of Sciences of the Czech Republic, told NBC News in an email.
“It approached the Earth from the direction of the sun, but even if it came from the opposite direction, there would be high chance that it would have been missed by the current survey telescopes during the few days before the impact when it would be observable.”

These rocks gotta go somewhere.

The artwork above is a depiction of the Nov. 13, 1833, Leonid meteor shower, which is scheduled to come around again next Wednesday.
Debris dashing about above our heads.

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