The Event: A large asteroid will hit planet Earth and the impact will cause worldwide devastation – including the possible extinction of most of the life on the planet.
The Impact: The amount of devastation will depend on how big the asteroid is and where it lands. Every day our planet is hit with small space objects (less than 10m in diameter) but most of these break up and/or burn up in our atmosphere turning into dust and ash, and don’t cause any damage. About once a year, a larger object enters the atmosphere but they almost always explode into small pieces (due to the rapid heating caused by friction with the air) and only a few are ever located. But on rare occasions, a large object will make it all the way to our surface and it will either explode in the air or hit the ground or water.
In 1908, a large explosion leveled a forest in Russia. The most plausible explanation is that a comet measuring 10 to 20 meters in diameter exploded in the air about 5 to 10 km above the ground. The explosion would have been about 1000 times more powerful than the atomic bomb dropped on Hiroshima. The area affected was over 2000 square kilometers and over 80 million trees were knocked over. Photos taken 20 years after the event show trees knocked down in a pattern suggesting a central explosion.
Elsewhere on our planet are the distinctive craters left when one of these objects actually make it to the ground. Here is a photo of one in Arizona. It measures 1100m wide and is 200m deep. Scientists estimate that this crater was created by a meteor measuring about 30m wide and weighing 100,000 tons.
One of the theories regarding the extinction of the dinosaurs is that a massive meteor hit the earth on the Yucatan Peninsula in Mexico (stay tuned for a series of posts about dinosaurs in a few weeks). The meteor has been estimated to be 10km in diameter, and created a crater more than 180km in diameter - most of which is under water. The impact would have created a megatsunami (a wave over 1000 feet high) and sent debris so high into the air it would have blocked sunlight and completely changed the global climate.
The Science: The development of telescopes over the past century has allowed us to see farther into space, but they have also allowed us to see smaller objects such as comets. We now understand that some of these comets have settled into orbits that are consistent and therefore predictable (such as the famous Halley’s comet which enters our solar system every 75 years). We also know that many space objects are unpredictable and the gravitational pull of the sun and other planets can change their trajectory so they could end up hitting earth. Between the planets Mars and Jupiter is a large collection of asteroids referred to as the asteroid belt. Most of the time, these asteroids orbit the sun in a stable orbit, but sometimes they collide with each other and pieces may have enough energy to leave the stable orbit and head towards the sun – which means they could get close to earth.
If you have ever looked at our moon with a telescope, you will have seen that the surface has many craters which are the result of meteor impacts. Since the moon does not have an atmosphere, or water, or active volcanoes, the surface doesn’t change so we have a good view of all the impact craters.
God has given us some built in protection against meteors. Our planet has an atmosphere surrounding it, which is a 100km thick layer of various gases held in place by gravity. While we tend to think of air as something with no mass, a strong wind will quickly remind us that air can do damage. As any object moves through our atmosphere, the air causes friction which creates heat. The faster an object moves, the more heat is produced. So when a meteor enters the earth’s atmosphere, it heats up very quickly. This rapid heating usually results in the meteor breaking into smaller pieces, which break into even smaller pieces, and many of these simply burn up and become fine dust. Maybe you have seen this for yourself watching the night sky – we call them shooting stars or falling stars.
Jac’s Analysis: In 1998, two movies were released about the possibility of a big comet heading towards earth. Deep Impact and Armageddon are reasonably accurate in their scientific explanation regarding how might react to a potential “earth killer” comet. In Deep Impact, one of the large fragments of the comet hits the ocean and creates a megatsunami. There is much devastation, but mankind survives. Outside of the world of fiction, spotting and tracking “near earth objects” or neos is on-going and so far, they haven’t found any objects heading our way that we need to worry about for the next century or so. We know from looking at the moon and different locations on earth, that big objects have been in our neighbourhood in the past, and will likely visit us sometime in the future. But based on the sheer volume of space (really, really big) and the relative small size of earth (pretty small), the odds of a large space object hitting us are truly astronomical.
Our Reaction? This event is unlikely, I don’t think we need to lose sleep over it. We need to trust that our God will continue to hold us in His hands and prevent this event from happening, or equip us to deal with it if it does.
Questions and comments?
1. Have you seen craters on the moon through a telescope? Have you seen “shooting stars”?
2. If you have watched Deep Impact or Armaggedon, do you think we are capable of deflecting a comet on a collision course with earth?
Next week we look at the final event – a deadly pandemic.
Jac
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