by Ann » Tue Sep 27, 2022 5:16 am
I applaud NASA for doing this experiment to actually deflect an asteroid - and they apparently succeeded, too.
At the same time, I'm reminded of what happened back in 2013, when NASA had told us that an asteroid would pass between the Earth and the Moon, really very close to us. However, it would not hit us. So when, on the day of close passage of the asteroid, newsflashes started talking about an extremely bright meteor over Russia, I just assumed that this had something to do with the passing asteroid.
Not so. It was the largest meteor to hit the Earth since
Tunguska event back in 1908. Both the Tunguska event and the new meteor event over Chelyabinsk, also in Russia, were caused by large rocky objects exploding in the Earth's atmosphere, creating enormous shock waves.
Wikipedia wrote about the Chelyabinsk meteor:
The Chelyabinsk meteor was a superbolide that entered Earth's atmosphere over the southern Ural region in Russia on 15 February 2013 at about 09:20 YEKT (03:20 UTC). It was caused by an approximately 20 m (66 ft) near-Earth asteroid that entered the atmosphere at a shallow 18.3 ± 0.4 degree angle with a speed relative to Earth of 19.16 ± 0.15 kilometres per second (69,000 km/h or 42,690 mph). The light from the meteor was briefly brighter than the Sun, visible up to 100 km (62 mi) away. It was observed over a wide area of the region and in neighbouring republics. Some eyewitnesses also felt intense heat from the fireball.
The object exploded in a meteor air burst over Chelyabinsk Oblast, at a height of around 29.7 km (18.5 mi; 97,000 ft).[7][8] The explosion generated a bright flash, producing a hot cloud of dust and gas that penetrated to 26.2 km (16.3 mi), and many surviving small fragmentary meteorites. The bulk of the object's energy was absorbed by the atmosphere, creating a large shock wave with a total kinetic energy before atmospheric impact estimated from infrasound and seismic measurements to be equivalent to the blast yield of 400–500 kilotons of TNT (about 1.4–1.8 PJ) range – 26 to 33 times as much energy as that released from the atomic bomb detonated at Hiroshima...
The object approached Earth undetected before its atmospheric entry, in part because its radiant (source direction) was close to the Sun.
...
The earlier-predicted and well-publicized close approach of a larger asteroid on the same day, the roughly 30 m (98 ft)
367943 Duende, occurred about 16 hours later; the very different orbits of the two objects showed they were unrelated to each other.
Here is a video where ABC News talked about the Chelyabinsk event:
Click to play embedded YouTube video.
To me, three things about the Chelyabinsk event stand out. It was the largest meteor to impact the Earth since 1908. It struck us at almost the same time as the world was waiting for a near-Earth asteroid to make its closest approach to the Earth. And it appeared "out of nowhere", completely undetected until it showed up brilliantly in the skies over southern Ural.
My point is this:
Will we detect a dangerous rocky object in time to be able to send up a probe to deflect it?
Ann
P.S. And of course... As I googled the Chelyabinsk meteor, I was struck by the pictures of Russia barely ten years ago, when the country was not at war, and Russian men were not being rounded up on the streets to be forcibly sent to Ukraine to be a part of Vladimir Putin's brutal unprovoked war against another country. You really have to wonder what was worse, the Chelyabinsk meteor or Vladimir Putin - and I think I know the answer to that. 
I applaud NASA for doing this experiment to actually deflect an asteroid - and they apparently succeeded, too.
At the same time, I'm reminded of what happened back in 2013, when NASA had told us that an asteroid would pass between the Earth and the Moon, really very close to us. However, it would not hit us. So when, on the day of close passage of the asteroid, newsflashes started talking about an extremely bright meteor over Russia, I just assumed that this had something to do with the passing asteroid.
[img3=""]https://www.universetoday.com/wp-content/uploads/2014/02/Chelyabinsk-fireball-dashcam-best.jpg[/img3]
[clear][/clear]
Not so. It was the largest meteor to hit the Earth since [url=https://en.wikipedia.org/wiki/Tunguska_event]Tunguska event[/url] back in 1908. Both the Tunguska event and the new meteor event over Chelyabinsk, also in Russia, were caused by large rocky objects exploding in the Earth's atmosphere, creating enormous shock waves.
[quote][url=https://en.wikipedia.org/wiki/Chelyabinsk_meteor]Wikipedia[/url] wrote about the Chelyabinsk meteor:
The Chelyabinsk meteor was a superbolide that entered Earth's atmosphere over the southern Ural region in Russia on 15 February 2013 at about 09:20 YEKT (03:20 UTC). It was caused by an approximately 20 m (66 ft) near-Earth asteroid that entered the atmosphere at a shallow 18.3 ± 0.4 degree angle with a speed relative to Earth of 19.16 ± 0.15 kilometres per second (69,000 km/h or 42,690 mph). The light from the meteor was briefly brighter than the Sun, visible up to 100 km (62 mi) away. It was observed over a wide area of the region and in neighbouring republics. Some eyewitnesses also felt intense heat from the fireball.
The object exploded in a meteor air burst over Chelyabinsk Oblast, at a height of around 29.7 km (18.5 mi; 97,000 ft).[7][8] The explosion generated a bright flash, producing a hot cloud of dust and gas that penetrated to 26.2 km (16.3 mi), and many surviving small fragmentary meteorites. The bulk of the object's energy was absorbed by the atmosphere, creating a large shock wave with a total kinetic energy before atmospheric impact estimated from infrasound and seismic measurements to be equivalent to the blast yield of 400–500 kilotons of TNT (about 1.4–1.8 PJ) range – 26 to 33 times as much energy as that released from the atomic bomb detonated at Hiroshima...
[b][color=#FF0000]The object approached Earth undetected before its atmospheric entry, in part because its radiant (source direction) was close to the Sun. [/color][/b]
...
The earlier-predicted and well-publicized close approach of a larger asteroid on the same day, the roughly 30 m (98 ft) [url=https://en.wikipedia.org/wiki/367943_Duende]367943 Duende[/url], occurred about 16 hours later; the very different orbits of the two objects showed they were unrelated to each other.[/quote]
Here is a video where ABC News talked about the Chelyabinsk event:
[youtube]https://www.youtube.com/watch?v=gRrdSwhQhY0[/youtube]
To me, three things about the Chelyabinsk event stand out. It was the largest meteor to impact the Earth since 1908. It struck us at almost the same time as the world was waiting for a near-Earth asteroid to make its closest approach to the Earth. And it appeared "out of nowhere", completely undetected until it showed up brilliantly in the skies over southern Ural.
My point is this:
Will we detect a dangerous rocky object in time to be able to send up a probe to deflect it?
Ann
[size=85]P.S. And of course... As I googled the Chelyabinsk meteor, I was struck by the pictures of Russia barely ten years ago, when the country was not at war, and Russian men were not being rounded up on the streets to be forcibly sent to Ukraine to be a part of Vladimir Putin's brutal unprovoked war against another country. You really have to wonder what was worse, the Chelyabinsk meteor or Vladimir Putin - and I think I know the answer to that.[/size] :cry: