Asteroids. My fear is real.

As if I don’t already have enough to worry about here on Earth. I also worry about what is happening in the outer regions of the solar system.

The fear exists because not only am I blessed with anxiety, I also like to have control of things. I know I sound like a dream, right? Luckily, I have found people who love me anyway.

It is really the lack of anyone having control over asteroids that creates my fear. I am just a sitting duck to whatever happens, or rather a sitting dinosaur since it was an asteroid impact that lead to the demise of that long-surviving genus.

Every so often we hear about a meteor that took everyone by surprise. An unexpected, unbelievably bright streak across the sky with a loud shockwave following it. How scary would that be? Enough to set hearts seriously aflutter, I’ll bet.

It just starts the brain running with so many questions. Why didn’t we know about it? What if it was bigger? What if it hit a densely populated city? What would I do if I was in that area and survived?

In this article, I will take a look at a few of the questions surrounding asteroids and their impact on us. See what I did there?


What is an asteroid?

Asteroid means star-like. Also known as planetoid, minor planet, or protoplanets.

There is often confusion about terms, so here is a beautiful poster by the American Meteor Society that sets the record straight.

Meteor and Asteroid Terminology

Meteor Terminology (Poster concept & design by Vincent Perlerin and Mike Hankey) Credit: American Meteor Society

Other abbreviations often used in discussions of Earth collisions…

Near-Earth Object (NEO) is an asteroid or comet with a closest orbital distance less than 1.3 AU.

Potentially Hazardous Asteroid (PHA) is an asteroid that is close to Earth (within a minimum orbit intersection distance, MOID, of .05 AU) and large (an absolute magnitude larger than 22.0, ~550 ft. in diameter).


Where do these asteroids come from?

There are several places in our solar system that house asteroids or comets that could venture our way.

1. Asteroid Belt

Obviously, the first on the list is the asteroid belt. It contains billions of asteroids. Despite this fact, if you were positioned next to one, you would be lucky to see another one. So forget about the Star Wars scenes where you have to dodge asteroids in order to pass through. Unless you are going lightspeed, but then you likely have the technology to avoid them anyway.

The asteroid belt was formed during the creation of the solar system. It originally had about 4 times the material used to create Earth. However, Jupiter had other plans. Its gravity cleared a lot of the material from that area to less than that of our moon, and also prevented it from coalescing into another planet.

Just a fun fact you might not know about, in addition to the space between the asteroids there are even larger gaps in the orbital path called Kirkwood gaps. Kind of like the many rings of Saturn, these rings are relatively free of asteroids. They occur at certain ratios of mathematical relationship with Jupiter.

Upon approaching Jupiter, the gravitational pull will either speed up or slow down the asteroid. This kind of kicks the asteroid to a larger or smaller orbital path. It is easy to slip into the thinking that items in orbit move in a circular path on their own, but they don’t. It is easier to understand these forces by remembering that without a gravitational force on them, the orbiting objects would move in a straight line.

2. Jupiter’s Lagrange points

Have you ever heard of Lagrange points? They are 5 specific points of gravitational equilibrium between 2 larger masses, like the Sun and Earth.

lagrange points

Lagrange points. Credit: NASA / WMAP Science Team

Depending on a number of factors such as mass, the points may be quite stable or require regular corrections for satellite to maintain position.These points make a nice home for natural and manmade satellites.

This is especially handy for scientists. Lagrange points allows them a view of our solar system and universe without the interference of our atmosphere. They can observe the Sun and solar weather. (See related: Beyond the basics of the Sun: 10 things you didn’t know) But, they may also observe the broader universe.

There are quite a few bodies that reside in the Lagrange points of Jupiter. They are called the Trojans and the Greeks. See the image below for their location.


Asteroid belt and Jupiter asteroids

The Jupiter trojans in front of and behind the planet along its orbital path, the asteroid belt between Mars and Jupiter, and the Hilda asteroids. Credit: Mdf at English Wikipedia, Public Domain


3. Kuiper belt

We don’t often hear about the extended reaches of our solar system. But there are other things beyond Pluto that are still a part of our system.

Have you heard about the Kuiper belt? The Kuiper belt is a collection of objects orbiting the sun beyond Neptune. It orbits on the same plane as the planets and consists mostly of comets along with other solar system debris.

Perhaps you have heard about the Kuiper belt with all the media buzz that came about when Pluto was “demoted” from planet to dwarf planet. The news often cited other Kuiper belt items of similar size as to the reason for the demotion. It was quite a heated debate. I guess there is no such thing as bad PR as long as attention is on space-related topics in the news.

4. Oort cloud

Beyond even the Kuiper belt is the Oort cloud. The Oort cloud is similar in composition to the Kuiper belt but it is further yet and it is in the shape of a sphere encasing the entire solar system.

It is thought that the objects in the cloud actually originated closer to the Sun than the asteroid belt. The objects were thrown far out due to the gravitational effects of the large planets. It is believed that long-period comets may be a part of the Oort cloud. Maybe they just want to return home?

It is difficult to prove its existence because the objects are so far, so small, and don’t reflect light. That makes them nearly impossible to observe.

Here is an artist’s rendering of what it probably looks like.

Kuiper Belt and Oort Cloud

Kuiper Belt and Oort Cloud. Credit: ESA


Another asteroid fun fact: If you are a space buff like me you have likely heard about binary stars. Binary stars are actually quite common. Apparently, asteroids may also be binary. Meaning that 2 similarly sized asteroids orbit a common center. This is different from when an asteroid as its own moon, another much smaller asteroid that orbits around the larger asteroid.


Why study them?

I would imagine that obliteration of the human race is a good enough reason.

However, while asteroids and comets are a threat to Earth, there is another side to them. They may benefit us. How?

First off, studying them can tell us more about the makeup of the solar system and add to our knowledge of how our solar system evolved.

Secondly, they could be a potential resource for colonization in our solar systems. If not to exist on, then to harvest resources from such as water and metals.


What would happen if an asteroid hit the Earth?

Actually, around 100 tons of space debris does hit the Earth’s atmosphere every day. Every day!! Thankfully, most stony meteoroids up to about 33 feet in diameter will be destroyed by the atmospheric entry.

Of course, there is a huge range of possible outcomes for things that survive the atmosphere. From us never noticing the dust in the air to global climatic disruption. Let us take a look at a couple scenarios…

  • Size of asteroid: a house
    • Energy: about 20 kilotons (~one Hiroshima)
    • Diameter of devastation: at least 3 miles
  • Size of asteroid: a 20-story building
    • Energy: about 25-50 megatons
    • Diameter of devastation: at least 10 miles
  • Size of asteroid: a mile wide
    • Energy: about 1 million megaton
    • Diameter of devastation: at least 200-400 hundred miles and beyond

Depending on where the asteroid struck makes a big difference as well. The majority of the Earth is water-covered. In that scenario tsunamis could cause massive devastation along coastlines.

If the collision occurred on land, nearby populations would clearly be affected. If it was large enough, dust and debris would be thrown into the atmosphere blocking the sun. This would result in widespread crop failures.

If people were lucky enough to live through a massive impact, society would be in danger. When people are desperate, they will do what they need to do to survive.


How likely is it that an asteroid will hit the Earth?

It is very likely to happen, eventually. So it isn’t a question of if, it is a question of when.

(See related: Predicting the future series: Who are futurists and is it a hoax?)

This is where it gets difficult. We need to use evidence of past collisions on Earth and evidence of collisions on our moon and other solar system bodies. With situations like that, it is like winning the lottery.

On the scale of global disruption, the best estimate is once every few hundred thousand years on average.

On a more local disruption, the best estimate is once every few hundred years on average.

Now, you need to consider the geography of Earth. Most of the Earth is covered in water. Much of the land is uninhabited or with smaller populations. So considering the average lifespan of humans today, it should ease some of your concerns.


How can we avoid this fate?

In order to solve a problem, we need to fully understand it. After we understand it we need to make a plan and act. So, how does this look…

  1. Detect it. We can’t fight it if we don’t know it is coming. Even if we are looking, we can’t see things in our blind spot which is in the direction of the Sun. That was the case with the incident in Chelyabinsk on February 15, 2013. The Sun essentially blinded us from seeing anything from that direction. Think driving at night with a car coming at you with their brights on. (See related: A save the sky guide: What is light pollution and what you can do about it)
  2. Understand it. Learn everything we can about it. Size, speed, spin, composition, lead time, trajectory, etc. We are making great strides with this ESA’s Rosetta mission landed a probe on a comet. NASA has landed a probe on an asteroid. These are enormous steps and are very promising for future missions.
  3. Make a plan. This is loaded with political issues. It has been identified as one of the bigger issues. Who acts? Who pays for it? What if the impact is in an area with no governing bodies? or no resources to give to the problem? Who will execute the plan? Who is responsible if something goes wrong?
  4. Execute the plan. There are several options of how to deal with incoming objects.
    1. Deflect it. This currently looks like to best option to date. The earlier the interception, the easier it would be. Small changes and long distances mean big changes. Suggestions for how to do this include: strategically placed bombs, rocket motors, sails, changing the volume/density with lasers, kinetic impactors, or gravity tractors. There is no shortage of creative ideas.
    2. Break it up. This is a more undesirable option. It would turn a single impact into multiple impacts across a larger area. It could also be very difficult with a disastrous risk of failure. Can you imagine those tasked with the job? Talk about pressure. Literally, saving the human race! Ugh.
    3. Evacuate the planet. Can you imagine our rocket attendants trying to calmly guide panicky people to their escape pods? This is assuming we wait until the last minute to exit as opposed to gracefully saying our goodbyes to Earth well before this happens. (See related: Do you wonder if there is life beyond Earth? Consider the Drake equation)


What is being done to watch and protect us from asteroids?

As it turns out, there are numerous agencies with their eyes to the skies. This provides for a necessary second opinion on any potential hazards. Not to mention, that is a large area to keep watch on.

Many of these organizations have information available online for the public. So you can look at the data for yourself. This did put my mind at ease. The process for observation is clearly identified and the data is organized. Missions have been completed and are planned for the future to further our understanding. Scientists are so awesome.

If you want to look at it for yourself, here are just some of the sites I found.

  1. NASA NEO program They “coordinate NASA-sponsored efforts to detect, track and characterize potentially hazardous asteroids and comets that could approach the Earth.
  2. E.A.R.N. They “...provide a means for easy and fast communication, exchange of data and other information in both observational and theoretical research on asteroids.
  3. Minor Planet Center They are “…responsible for the designation of minor bodies in the solar system: minor planets; comets; and natural satellites.”
  4. International astronomical union NEO page They are charged to “…liaison with SpaceGuard Foundation, advise on coordination of NEO activities worldwide, advise on reporting of NEO hazards, and advise on research relevant to NEOs.
  5. Pan-STARRS “A major goal of Pan-STARRS is to discover and characterize Earth-approaching objects, both asteroids & comets, that might pose a danger to our planet. “
  6. Spaceguard Central Node They “…promote and co-ordinate activities for the discovery, pursuit (follow-up) and orbital calculation of NEOs at an international level.


Does that quell some of your fears?

Reading about the work being done did make me feel better. You?

At least we have some information. Fear of the unknown and uncertainty is awful. Now we need to get with the program and determine some good processes. Develop the what if scenarios and put some money behind it. That way we don’t waste precious time when the need arises.

It sounds like a lot of it boils down to politics. Hopefully, scientists can overcome those issues for the greater good.

What is the boy scout motto…always be prepared? Sounds applicable to me.

I still don’t want to watch any of those end-of-the-world movies featuring asteroids. Especially close to bedtime. But for now, I will sleep a little better being more informed on the subject.



American Meteor Society

Asteroid Belt: Facts & Formation from

Asteroid Belt vs. Kuiper Belt vs. Oort Cloud from The Solstice Blog

Barnes-Svarney, Patricia L. Asteroid: Earth Destroyer or New Frontier? New York: Plenum, 1996. Print.

Burrows, William E.. The Asteroid Threat: Defending Our Planet Frrom Deadly Near-earth ObjectsComplément Du Titre. New York: Prometheus, 2014. Print.

Miller, Ron. Asteroids, Comets, and Meteors. Minneapolis, MN: Twenty-First Century, 2006. Print.

Near Earth Object Program from NASA

NASA EDGE: Planetary Defense from NASA

NEODyS-2 from ESA

The Lagrange Points from WMAP NASA

The Probability of Collisions with Earth from NASA JPL

Touchdown! Rosetta’s Philae Probe Lands on Comet from NASA

What if an asteroid hit the Earth? from How Stuff Works Science