Explosion reported near the Nicaraguan capital attributed to meteorite impact, but experts, including NASA, cast doubt on claims
Tuesday, September 9, 2014, 10:42 AM - (Update: The story has been updated to reflect new evidence and analysis from experts.) News has been circulating about a potential meteorite strike near Managua, Nicaragua late Saturday night, just 13 hours or so before the close flyby of 20-m asteroid 2014 RC, leading some to suggest that the two events are related. However, according to experts who have been examining the evidence, including those at NASA, the two events are completely unrelated, and the explosion in Managua may have nothing to do with objects falling from space.
According to the Nicaraguan news site el19digital.com, an explosion occurred around 11:05 p.m. Saturday night, in the city of Managua, which apparently produced a crater that was over 12 metres (39 feet) wide and about 1.5 metres (5 feet) deep, in a wooded area just to the west of the city's international airport, and just south of the Pan-American Highway.
The video below, from RT.com, shows military personnel investigating the crater, as well as the surrounding area, for potential debris from the explosion.
While the incident is still being investigated, officials with Nicaragua's Institute of Territorial Studies (INET), which monitors earthquake activity in the country, said that the event showed up on the agency's seismic instruments.
"We are convinced that this was a meteorite. We have seen the crater from the impact," Wilfried Strauch from INET said in a press conference, according to Agence France-Presse (AFP). "You can see two waves: first, a small seismic wave when the meteorite hit earth, and then another stronger one, which is the impact of the sound."
However, while there have been reports of people hearing the explosion, the scientists have the seismic data from it, and they have the resulting crater, there are parts of the story that just don't add up.
Connection with 2014 RC?
A 20-metre wide asteroid named 2014 RC passed by Earth on Sunday, flying underneath the planet (from the perspective of someone in the northern hemisphere), and while there is roughly a 13-hour difference in the timing of these two events, some saw a potential connection between these events. It's not entirely unreasonable to suggest this. There are over 11,000 known near-Earth asteroids flying around the Sun, and very likely millions that we haven't detected (and likely won't, because they're too small). While most of these follow their own path as they circle the Sun, not all are alone. Some asteroids have tiny moons orbiting them. Some are best described as 'rubble piles', which are groups of smaller objects only barely held together into a boulder-like shape by their mutual gravity. Others can be travelling along in 'packs' with some members preceding or lagging behind the 'pack leader' - possibly due to an impact with another meteoroid or asteroid at some point. So, if one of these asteroid 'packs' is flying by, or an asteroid that still has debris from a past impact travelling along the same orbit, it is possible that one piece could strike the atmosphere and survive to hit the ground.
However, just because two events - an asteroid flyby and a meteorite impact - happen close to one another, doesn't mean that they are related. We saw this back in mid-February 2013, when we were watching asteroid 2012 DA14 sweep by Earth and suddenly a 20-m wide asteroid exploded over Chelyabinsk, Russia. The exact timing and traced orbits of these two objects quickly showed that they were completely separate objects and the timing was a just coincidence.
According to NASA's Jet Propulsion Laboratory Near Earth Object Office, that appears to be the case for this event:
For those wondering, the event in Nicaragua (poss meteorite?) is unrelated to asteroid 2014 RC. Different timing, different directions.— Asteroid Watch (@AsteroidWatch) September 8, 2014
A meteorite without the meteor?
An interesting fact about this supposed 'impact' is that, although the explosion was heard throughout the area, apparently nobody witnessed any bright light associated with it. When a meteoroid enters the atmosphere, even if it is just a speck of dust, it is traveling so fast (typically around 17 kilometres per second or over 60,000 km/h) that it heats up the air in front of it, causing the air to glow brightly and produce the streak of light in the sky we call a meteor. Larger objects cause even brighter flashes, earning them the name fireball,or even bolide (for an exceptionally large and bright one). Some of these are so bright that they can, very briefly, turn night into day as they pass overhead.
Given the weather over Managua on Saturday night (scattered clouds and calm winds), it would have been very difficult to miss such a fireball or bolide lighting up their night sky, especially when it happened near a city of over 2 million people.
According to the Associated Press, Strauch said it was "very strange that no one reported a streak of light. We have to ask if anyone has a photo or something."
Was it something else?
This lack of a fireball is a sticking point in the story. While nearly all meteorites go through a 'dark flight' phase during the final part of their journey to Earth's surface - after it has slowed down enough that it isn't compressing the air enough to cause it to glow - their fireball or bolide stage happens far up in the atmosphere, some 20 to 30 kilometres above the ground, making them visible far and wide across the countryside.
For all who asked: I don't think the Nicaragua "crater" is real. Doesn't look fresh, no eyewitnesses, should not have rocks at bottom.— Geoff Notkin (@geoffnotkin) September 8, 2014
Also a meteorite making a crater that large would have been preceded by a gigantic fireball. No eyewitnesses? Near an airport?— Geoff Notkin (@geoffnotkin) September 8, 2014
Notkin further commented that if it was meteorite-related, he would expect there to be a very bright fireball, sonic booms during the object's dark flight and then the impact. He also said that, to produce a crater like the one seen, it would have to be an iron meteorite, as they are the densest and "have formed the majority of known meteorite craters on Earth"
In an interview with National Geographic, Donald Yeomans, the author of Near-Earth Objects: Finding Them Before They Find Us, said: "There was no obvious optical fireball or debris trail seen prior to the explosion, so it seems unlikely that the explosion in Nicaragua was related to a meteorite impact."
So, what was this, if it wasn't a meteorite? One very real possibility is that it was a landmine explosion, as there are still thousandsIn cas buried throughout the country, remnants of the war fought there in the 1980s.
While this particular event is looking more and more like a false alarm with time, it should be noted that fireballs blaze through our skies every day, as tons of material is swept up by Earth as the planet orbits the Sun. Many of these are missed because they occur during the day, or over regions of the planet that aren't heavily populated. Some countries have all-sky camera networks to capture these events, with data being reported on sites like SpaceWeather.com (U.S.) and the University of Western Ontario (Canada). As an example, there was a bright fireball that occurred just before this explosion in Managua, but it happened thousands of kilometres away across the Atlantic Ocean, over eastern Spain, as shown in this animation taken from railway camera video (note what appears to be a second object that may be a piece breaking off the primary one):