Over the past few days we've witnessed two celestial events involving near earth objects and one very interesting lightning strike.
In reverse chronological order, today we saw the closest approach to Earth of a medium-sized asteroid since the Tunguska event of 1908. The explosion from the latter incident occurred at about 7 am local time June 30, 1908 in a forested area near the Tunguska River in Siberia. Thank goodness for that - the force of the explosion has been estimated to be between 5 and 30 megatons, with 10-15 megatons being the most likely - about 1000 times more powerful than the atomic bomb that destroyed Hiroshima. As it was, the Tunguska detonation knocked down an estimated 80 million trees in an area of 830 square miles.
So how does today's fly-by of Asteroid 2012 DA14 compare to Tunguska? Most importantly, DA14 missed. The closest it came was 17,200 miles. Galactically speaking this is close - it's within the orbit of many of our satellites, less than 10% of the distance from the Earth to the Moon, and about 70% of the circumference of the Earth. When DA14 comes back around 2080, there is a very slight chance that it may impact the Earth. according to one of the commentators on the NASA live feed today. Size-wise, DA 14 is about half the diameter of the object that impacted Tunguska. Even at half the size, had DA14 hit (or if it hits in 2080) it still would have packed a 2.4 megaton punch.
Also interesting is how far we've come since Galileo used his telescope to view the moons of Jupiter. This asteroid was first noted by an amateur astronomy group scanning the skies in Spain just under one year ago. And today, even during the daylight here in the US, the Internet allowed transmission of live video from observatories in other parts of the world - particularly Australia.
Discovery.Com has a webpage "How to Watch Asteroid 2012 DA14 Zoom Past Earth" that is informative and even contains a link to one of my favorite questions "How do you stop an asteroid?" Among the possible answers: nuclear weapons (Note 1), kinetic nudging, vaporizing it with mirrors, netting it, painting it and several others. In the final analysis, though, what happens if it's too late to do any of these things? The website analysis: evacuation would be the only and last resort.
Okay, enough for today's asteroid. Just 16 hours before 2012 DA14 reached its nearest approach to Earth, a meteor streaked across the Russian Urals. Per the AP as reported in the Huffington Post: "With a blinding flash and a booming shock wave, a meteor blazed across the western Siberian sky Friday...injuring more than 1,000 people as it blasted out windows and spread panic in a city of 1 million... The meteor above western Siberia entered the Earth's atmosphere at a hypersonic speed of at least 54,000 kph [33,000 mph] and shattered into pieces about 30-50 kilometers (18 to 32 miles) high, the Russian Academy of Sciences said." NASA estimated that the meteor released "300 to 500 kilotons [0.3 to 0.5 megatons] of energy and left a trail 300 miles long." There is apparently no connection to DA14 but I don't think I'm going to be moving to Siberia anytime soon. The place this meteor hit is about 1500 miles from Tunguska. I know - Siberia's a big place..still...
Finally, on Monday February 11, Pope Benedict XVI announced his resignation from the Papacy. Two hours later, lightning apparently struck the dome of St. Peter's Basilica. I'm not sure what this has to do with anything but I thought it was a rather interesting coincidence also. Popes do not normally resign. The last to do so was Gregory XII, 598 years ago.
Note 1 - In the State of Dis-Union post, I recommended we keep 5 of the current 15,000 nuclear warheads around for this purpose...I stand by the figure. Asteroids of this size hit Earth about once every 1200 years or about twice as long as the time since the last papal resignation.
Note 2 - I also recommended in the State of Dis-Union that you go to sleep before Marc Rubio spoke. Actually that may have been a mistake...the apparent high point of Rubio's speech was when he took a sip of Poland Spring water. Jon Stewart had a hilarious bit on the Republican response.
Note 3 - What's the difference between a meteor, meteorite, comet and asteroid? TheBlaze website has a succinct definition of these terms.
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