From the “bigger worries than global warming” department:
Guest essay by Eric Worrall
Yet another indication that Asteroids are a far more serious threat than climate change. NASA scientists have just in the last few weeks detected a previously unknown Asteroid, a quarter of a mile across, approaching at an unusually high speed of 35km / second, which is due to narrowly miss the Earth on 31st October this year. The asteroid will only approach within 1.3 lunar distances of Earth, so this particular body poses no threat – but in terms of the scale of the solar system, this upcomming event counts as a very near miss. This asteroid is a wakeup call, a reminder of just how vulnerable we are to catastrophic impacts, and how little warning we might receive if such a threat were detected.
According to NASA;
2015 TB145 was discovered on 2015 Oct 10 by the Pan-STARRS I survey. The object will approach the Earth within 0.00326 au (1.3 Lunar distances or about 490 000 km) on 2015 Oct 31 at about 17:00 UT (10 AM PDT). The asteroid is in an extremely eccentric (~0.86) and high inclination (~40 deg) orbit. It has a Tisserand parameter of 2.937 hinting that it may be cometary in nature. Its absolute magnitude of 19.8 indicates that its diameter is probably within a factor of two of 320 meters. At closest approach the SNRs/run at DSS-14 are expected to be over 20000, so this should be one of the best radar targets of the year. We hope to obtain images with a range resolution as high as 2 m/pixel using DSS-13 to transmit and Green Bank (and possibly Arecibo) to receive. The flyby presents a truly outstanding scientific opportunity to study the physical properties of this object.
The encounter velocity is 35 km/s, which is unusually high.
This is the closest approach by a known object this large until 1999 AN10 approaches within 1 lunar distance in August 2027. The last approach closer than this by an object with H < 20 was by 2004 XP14 in July 2006 at 1.1 lunar distances.
2015 TB145 could reach 10th magnitude before sunrise on October 31 for observers in North America, but it will be close to the waning gibbous Moon and probably challenging to see with small telescopes. The asteroid will be in Ursa Major at the time of closest approach. After closest approch 2015 TB145 will be a daytime object and too close to the Sun to observe with optical telescopes.
Radar observations are planned at DSS-14, DSS-13, Arecibo, Green Bank, and elements of the VLBA. Observations may also occur with the UHF radar at Haystack.
If an unusually fast asteroid a quarter of a mile across struck an inhabited part of the world, the explosion would be many times larger than the half megaton Chelyabinsk meteor explosion, which was caused by a meteor with an estimated diameter of 55 ft. The explosion would be in the 10s of megatons, rivalling the largest atom bombs ever detonated – more than large enough to devastate an entire city.
How likely is such an impact? Thankfully really large impact events are very infrequent, though multi kiloton impact events are common – at least 26 such events have been detected since 2001, mostly in uninhabited regions. But there is no upper limit to the size of an impact event, and as this recent imminent near miss demonstrates, a serious threat could arise with very little warming.
What could be done to mitigate asteroid impact risk? At the very least better monitoring systems could be deployed, to try to provide at least some warning. Chelyabinsk received no warning when it was struck by a meteor. This asteroid was only detected a few weeks ago.
With enough warning people could be evacuated from likely impact zones. Even very large threats could potentially be addressed, if there was enough time to prepare.
In my opinion it is obscene that the world is spending countless billions chasing the imaginary perils of the climate dragon, while neglecting a far more serious threat to people’s lives.