The greatest danger asteroids pose to us is not from the impact

By Leah Crane, New Scientist

Wind kills. The most casualties from an asteroid impact won’t come from the impact itself. The wind, pressure and heat caused by the crash are far more dangerous, no matter where the asteroid hits.

Clemens Rumpf at the University of Southampton, UK, and his colleagues have calculated the mortality risk, should an asteroid hit a residential area. They considered asteroids that burn up completely, those that hit the ground, and those that strike in water. Surprisingly, the airborne side effects were the ones that cost the most lives.

As an asteroid hurtles towards the ground, it deposits a huge amount of energy into the atmosphere, resulting in a powerful shockwave, tornado-like winds and a plume of fire trailing behind it. When it crashes down, it forms a crater, shaking the ground around the impact and hurling debris into the air.

If the asteroid hits water (which is twice as likely as hitting land), it would create a tsunami, with waves reaching dozens of metres high. The farther from shore the impact is, the deeper the water and the taller the waves.

asteroid impact tsunami wind planetary defence

Credits: Getty Images

Far-reaching effect

In the past, people have shown that tsunamis posed the greatest risks from an asteroid impact, but the events are notoriously difficult to model. Rumpf and his colleagues have worked out that the continental shelf helps protect the shore by dissipating waves both at its steep edge and over its gentle beachward slope.

“What sets tsunamis apart is that they’re really the most far-reaching effect of all the impact effects,” says Rumpf. A pressure wave or heat plume can’t travel very far, and craters only form right at the impact site, but tsunamis can traverse hundreds of kilometres of ocean to hit coastal communities.

A tsunami caused by the impact of a 200-metre-wide asteroid 130 kilometres off the coast of Rio de Janeiro, for example, could cause more than 50,000 deaths, with 75 per cent of those being directly caused by the tsunami and the rest due to high winds.

But an asteroid over or in a city would kill millions. Most of those deaths would be due to wind as well, even if the asteroid did crash to the ground instead of exploding in the air.

For an airburst, about 15 per cent of casualties would come from heat. In a direct impact, the effects of gusting wind and surging temperatures are joined by pressure waves, which can rupture internal organs.

Only about 3 per cent of casualties would be caused by the actual impact or the earthquakes and debris that result, says the team. The group plans to discuss the results with disaster managers to come up with suggestions for preparedness.

Very rare events

Luckily, large asteroids don’t hit Earth often: an impact by a 200-metre asteroid is expected only once every 40,000 years. And an asteroid could fall anywhere, and most of the planet’s surface is unpopulated.

“Chances are that an asteroid hits the water, and even if it hits land it’s much more likely that it will hit away from populated regions,” says Rumpf. “These are very rare events, but with potentially high consequences.”

In case you are starting to worry, there are lots of projects dedicated to planetary defence against asteroids: telescopes have spotted most of the big ones, and there are several potential ways to avoid an asteroid impact if we see it coming.
“We are in the business of detecting asteroids well in advance of an impact, so this kind of work is only really important if we totally fail to do our jobs,” says Erik Christensen, director of the Catalina Sky Survey at the University of Arizona.

Journal reference: arXiv:1702.05798

Original article here.

NEOShield-2 note:

NEOShield-2 is a collaborative R&D project as part of the EU’s Horizon 2020 programme aimed to develop technologies necessary to implement space missions that could divert an asteroid from its path, thus preventing it from colliding with us, and also to refine Near Earth Object (NEO) characterisation through astronomical observations to improve our understanding of their physical properties, and to identify further objects suitable for missions for physical characterisation and NEO deflection demonstration.

Get to know more about us here.

NEOShield-2 Event in Nepal, Remembering the Chelyabinsk Event

Reported by Sushil Bhattarai, Kathmandu, Nepal

We all are Homo sapiens species. Human beings most relay on one affair with a common voice, “sharing is caring,” and so we care about each other. We successfully completed the task of delivering the world’s biggest technical issue about “Asteroids”. Credit goes to all of school members and international persons who profoundly helped to complete the first NEOShield-2 activity in Nepal. I believe it was a challenging task to introduce all about asteroids that hold some story from history of impacts to upcoming possible threats in a smooth way. Seriously, they were school level kids; at such age level, they are sensitive enough to create a terrible fear inside, psychologically. Therefore, it is a critical task to provide them both the information about NEOs threats and its mitigation measures simultaneously. Staffs, students, and teachers were visiting the event, so altogether over 200 members from the school got the chance to know more about the topic. The regular participants from starting to the end were the students from grade 5 to grade 10. The venue was Mokshada School’s main hall, 2017 Feb. 15.

Background and Motivation

I am physics student and a science educator too. I had also done a similar project related to NEOs observing impact and flash in the lunar surface at B.P Koirala Memorial Planetorium, Nagarkot in 2014, using the largest government telescope in Nepal. In 2015, I organized one-month long event to detect some asteroids using the official software called Astrometrica with my students during a research sponsored by IASC, an asteroid hunt, from Nepal. I am always motivated that I have decided to go into depth of physics and astronomy forever. I love to work with public and in-group so I have been working cooperatively involved in various national and international organizations for years.


I got help from many people to this event. Those helps were from the NEOShield-2 Team, the people from the school organization and everyone who had played a crucial role to complete this event smoothly, I appreciate, and this is for the future and wellbeing of the humanity.

Before NEOShield-2 Presentation

It was the beginning of the introduction session about “Asteroids”. Students in the hall were actually already familiar with the name “Asteroids” because they have lived some years of their life somewhere inside the realm of internet and technology. It was so cute that some students said Asteroids are like a stone or rocks that are in the sky; really, Asteroids are in the sky, but how about space! Space is a far thing they could imagine. The happiest moments exploded, literally like meteors shower inside the presentation hall when they said they were already familiar to some name like Comets, Meteors, and again Asteroids. Some students from grade 8, 9, and 10 were even richer with knowledge about “Asteroid Belt” and “Kuiper belt.” It was unbelievable that some of the students suggested us to use thousands of bullets that we could target and destroy the incoming Asteroids. I was laughing from inside but hardly I controlled, what I did just listened to them for about 2 minutes. After a lecture about speed and the size of the Asteroids they got more information about the killer asteroids. Indeed, students came to know that every country need to unite against asteroids otherwise we are nothing in front of such giants.

NEOShield-2 Agent Nepal Sushil Bhattarai

Students happy to get some extra information materials provided by NEOShield-2

Wonderful theatre

All kids are happy to go to theatre, and that is even cooler when it is inside their own school. On 15 Feb. 2017 for about 2 and half hours they were happy to not have to only read their bulky books. It was a new day, straight marching from the school assembly into theatre, happy in the hall.

NEOShield-2 Agent Nepal Sushil Bhattarai

NEOShield-2 Agent Sushil Bhattarai in front of the students while getting prepared in the theatre

NEOShield-2 Slide Presentation

It was a silent moment when students saw the slide containing report from February 7, 2017 ESA’s NEOCC lists: 15,622 NEAs, 3,449 comets, and 598 NEOs are potentially in the ‘risk list’. Some of the pictures and event videos showed at the presentation about the small asteroids that disintegrated in the earth’s atmospheres since 1994 to 2013 made our students picked up to eye opened.  Later some slides contained mitigation measures from asteroid impact was somewhat a relieved from inside that I could easily see from some students.

NEOShield-2 Agent Nepal Sushil Bhattarai

Sushil demonstrating actual size of the solar system and some asteroids

NEOShield-2 Agent Nepal Sushil Bhattarai

NEOShield-2 agent Sushil giving a Powerpoint presentation about mitigating measures from NEOs

Program featured

We know these kids are learning about space and asteroids, so they need to build some basic background knowledge about actual size of the solar system and its comparative study with the size of planets. In addition, the topic like planetary formation was also introduced with illustrating pictures and videos before the actual program starts. Here are some features and achievements of the event:

  1. Scale of solar system and the planet Pluto (a video documentary show);
  2. Q&A session about the previous video;
  3. Brief Asteroid Introduction: composition, size, velocity and its energy released when it strikes our planet (a video presentation);
  4. NEOShield-2 content material presentation in brief (a slide show);
  5. A compiled video documentary show about “Chelyabinsk shockwaves.” To make them realize the energy of shockwave generated by asteroid during its entry;
  6. “A brief introduction about how asteroid really had killed the dinosaurs.” Physics behind the scene;
  7. “Recreating asteroid strike that killed dinosaurs.” A lab experimental video by NASA;
  8. “Impact records from 2000 to 2013” demography was displayed so that students could figure out it is almost a daily incidents. Just bigger asteroids are dangerous;
  9. A quick overview of the mitigation measures, NEOShield-2, Civil defense and social awareness;
  10. Lastly, a discussion session. Students and teachers asked various curious and interesting questions raised in front me to answer.

Future Events and Motivation

Actually their innocence and frequent questions triggered to boost motivational level to some higher. Some of the questions were like: how the rocket and satellite move in the space? Why will not they fall into earth due to gravity? In addition, at the end of the event they asked me to describe some details about how could a single asteroid become a deadly weapon to wipeout our planet Earth. This session lasted longer period. I was not feeling tired of giving answers to them because the questions were so important that they deserved to listen to all the answers. This is a great idea of understanding the child psychology too, it can help to answer how the children of certain country are taking the science of Near-Earth Asteroids; we can understand them and such kind of public events are needed to be held in a similar way or even better in the future. But it is not enough; there are several hundred thousand of students lying in the remote part of the country. I am afraid if a real asteroid comes to destroy our planet and the news broadcasts does not satisfy the children’s queries, how they would be affected psychologically before the asteroid hit the planet. They will be killing themselves inside due to fear of asteroids before the real asteroid touch the atmosphere of the Earth.

NEOShield-2 Agent Nepal Sushil Bhattarai

Students paying great attention to information about Asteroids crawling in the vast space


NEOShield-2 Note:

The NEOShield-2 team is very glad to have Sushil as our new Agent in Nepal. We congratulate him for all his effort and great initiative of teaching all these students about asteroids, asteroids impact threat and mitigation measures. We hope to see and post more activities like this one in the close future.

Are you also interested in becoming a NEOShield-2 Agent and help us to spread awareness about an asteroid impact threat? Check more information here.

Picture Quiz: Chelyabinsk Event Anniversary

UPDATE: The Quiz is over now. Stay tuned for more quizzes and contests!

It’s been 4 years since the Chelyabinsk Event.

And we prepared a picture quiz for you!

Chelyabinsk Event Picture Quiz

About the Chelyabinsk Event

On February 15, 2013, an approximately 20m near-Earth asteroid entered Earth’s atmosphere over Russia.

With a speed of approximately 60,000 km/h, it quickly became a brilliant superbolide meteor.

The explosion released approximately 30 times as much as energy as that released from the nuclear bomb over Hiroshima.

The blast created by the meteor’s air bust produced extensive ground damage.

Around 1,500 people were injured and over 7,200 buildings were damaged.

With a total mass of 654 Kg, the largest found fragment of the meteorite was raised from the bottom of the Chebarkul Lake.

The Chelyabinsk meteor is thought to be the biggest natural space object to enter Earth’s atmosphere since the 1908 Tunguska event.

Live Stream: Asteroid Day Press Conference February 14, 2017

Asteroid Day to Announce Increased Global Support and Preview 2017 Events at February 14 Press Conference – Live from Luxembourg City, Berlin, Silicon Valley, Bucharest and London.

TIME: 2.30PM – 3.30PM CET | 08.30AM – 9.30AM EST


Luxembourg City

Berlin, Germany

Bucharest, Romania

San Jose, California, US

London, UK

  • Debbie Lewis, Asteroid Day Risk Management expert; Expert Panel Deputy Chairwoman