How to Survive a Comet Hitting Earth

Co-authored by wikiHow Staff

Last Updated: February 1, 2023 References Approved

While the chances of a large comet hitting the earth in the next several hundred years is improbable according to scientists,^{[1]
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Research source} it doesn’t mean that it can’t happen. 65 million years ago, an asteroid hit earth, which many scientists believe caused the extinction of the dinosaurs.^{[2]
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Research source} While 100 tons of material enter our world everyday, much of the debris is small and most of it burns up in our atmosphere.^{[3]
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Research source} However, if a large comet did hit earth, the destruction would be catastrophic. That's not to say that all humans would perish, however, as there are ways to use survival tactics in order to stay alive.

Part 1

Part 1 of 3:

Preparing For Impact

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Pay attention to astronomers’ predictions on any possible collisions with earth. NASA currently has astronomers that track comets that are flying in our solar system.^{[4]
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Research source} As a result, there’s a very good chance they will know if there is a large object about to collide with us. By listening to their predictions, you can develop a real sense of how much time you have to prepare.
- Check back with the NASA website, as they constantly update close calls.
- Make sure to prepare well in advance. Sometimes astronomers know about potential impacts on the earth only a couple months beforehand.
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Move away from coastal areas. Because the earth is made up of 71% water, there’s a greater likelihood that the comet will hit a body of water.^{[5]
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Research source} If this does happen, it could mean that giant tsunamis would be created by the initial impact and they would likely destroy our coastal cities. Additionally, there would be an increase in water vapor entering our atmosphere which would cause heavy rain, which could cause landslides and flooding.^{[6]
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- The tsunami in India in 2004 killed 150,000 people in a single day with many more left missing. The results of a tsunami from a large comet impact would be even worse.
- Even if you had an impenetrable bunker near the coast, massive flooding would mean you could never leave it.
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3
Move into a bunker or fortified structure and outfit it with an energy source. An underground bunker isn’t only the best for the time of impact; it will also protect you from environmental hazards after the comet has hit. When the comet hits, dust, soot, and water will shoot up into our atmosphere, making it cold for months to years.^{[7]
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Research source} For that reason, make sure you also outfit your bunker with an energy source for heat, like a generator and enough fuel to last while the dust in the atmosphere settles. If you're unable to get a bunker, make sure to fortify whatever structure you're going to be staying in so that it can withstand the blast. Buildings that have strong foundations and are lower to the ground are better.
- If you can't find a bunker, try to find another location that's going to be unaffected by the impact. This could be a cave or another natural structure that would shield you from the initial blast.
- There are many different bunker options available, but the best ones for a comet impact will have an air filtration system and be made of strong material.
- Bunkers can be expensive and range from anywhere from $20,000 to a million dollars and upwards.
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Purchase enough food, water, medicine, and other supplies. If the comet does hit on land, dust and rock particles flying into our atmosphere will make it too dangerous to go outside for months to years. Make sure that you have enough food that’s able to stand the test of time. A radio, handheld transceiver or walkie-talkie, and flashlights are other important pieces of gear you should stock up on.
- Make sure to stock your hide-out with canned food, dried goods, non-perishable foods, and bottled water.
- If there is more than one person staying in your location, make sure that you increase the amount of food you are storing accordingly.
- The average calorie intake for men is 2,500 calories a day and 2,000 calories for women.^{[8]
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Buy weapons and ammunition for after the impact. You may be more concerned with withstanding the destruction of the comet impact itself, but you also need to be conscious of the possible dangers of other people after the dust settles. If you are fully prepared for a comet impact and others are not, people may want to steal your resources. You should be ready to defend them unless you have enough to go around.
- Don’t go overboard on purchasing guns - make sure that you have things like food, water, and shelter before spending money on protection.
- A semi-automatic rifle and a pistol with enough ammunition should be more than enough firepower.

Part 2

Part 2 of 3:

Surviving After Impact

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Ration your food and water. The amount of time that the repercussions of a comet impact would negatively affect the outside environment depends on a variety of factors, like how large the comet was, where it impacted, and how close you are to the site of impact. Because of this, rationing your food and water may be crucial for your survival, as there’s no concrete amount of time you will need to sustain on your food stores.
- Dried legumes, canned beans, and dried meat products provide the most protein and can be stored for a very long time. Nutrient-rich grains and potatoes can also provide needed calories, so make sure to be stocking up on these kinds of food.^{[9]
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- As a rule of thumb, try not to dip below 500 calories a day. While humans are capable of surviving without food for up to 40 days while hydrated, not eating enough will deteriorate your body and mind.^{[10]
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- Make sure you are eating the right kind of foods so you don’t suffer from malnutrition.
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Limit your generator usage and only use it if necessary. Your generator will be a lifesaver for many things while you are in your bunker. You can use it to produce heat, cook food, and power lights. However, because most generators run on fuel, it’s important that you limit its usage because you will likely have a limited amount of fuel in your bunker. If you aren't in a bunker, a generator may still work, but there's a good chance that the main power grid will be down.
- It’s a good idea to have more than one generator in case your primary generator breaks.
- Equip your hide-out with generator repair kits for possible repairs that will be needed.
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Listen to the radio to stay in communication with society. There may be efforts from the government to try to help people during this catastrophe. Make sure to listen to the radio to see if there are any updates or initiatives that can benefit you. If there are people on the radio, they will likely be able to give reports on the environment outside.
- Don’t believe everything you hear. Early reporting is notoriously inaccurate at times, so wait it out until you hear unified reports.^{[11]
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- The National Weather Service broadcasts emergency broadcasts on the VHF public service band, which require a special radio receiver. These channels range from 162.400 to 162.550.^{[12]
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Keep yourself physically healthy. Any physical ailment while you are hiding out can develop into a life-threatening illness because of the lack of medical care available. A small cut could get infected, or a cold could develop into a chest infection. For that reason, you should attend to any medical issues as soon as they arise.
- While you ration your food and water you’ll probably want to keep physical activity low, but you should also make sure not to become frail while in your bunker and try to get exercise in if your food stores will allow it.
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Keep your mind active and stay mentally healthy. It will be very easy to be negative during such a catastrophe, so make sure that you keep an active mind. Solitary confinement has been proven to have negative physiological effects on people, so it's important that you use what you have around you to stay mentally acute. Reading books, talking to other people, and doing activities will ensure you aren't stagnating and keep your mind healthy.
- Isolation has multiple negative effects on your mental health, so having people with you is a good idea if you want to stay mentally healthy.^{[13]
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Part 3

Part 3 of 3:

Starting A New World

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Make sure the environment is safe before going out into the world. Use a portable air monitor to test the air outside and make sure that the levels are normal before venturing there. You also need to make sure that any fires or flooding caused by the comet have subsided. Acid rain is also a potential result from massive fires putting pyrotoxins into the air, which would make going outside deadly.^{[14]
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- Have a reason to go outside, like being out of food or supplies, or hearing about other groups of people who survived and wanting to join them.
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Scavenge for additional supplies and food. Whatever the comet did not destroy can be salvaged for use, like food, batteries, water, or anything else you’d find useful from abandoned stores and houses.
- Make sure that you are not stealing from anyone and that the goods have been abandoned by their previous owners to avoid confrontations.
- There is a chance that the location you try to scavenge in has already been sorted through, depending on the length of time you’ve been hiding out.
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Prepare to defend yourself from desperate survivors. If you’ve managed to survive the comet impact, there’s a good likelihood that others have as well. Hunger breeds violence and people will want to your steal supplies in order to survive.^{[15]
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- Always try to resolve things peacefully, not violently.
- There may be other groups willing to share resources as long as you share yours.
- Always approach people cautiously, but not in a hostile manner.
4
Move to a fertile place near the equator and plant vegetable seeds. Non-perishable and canned food won’t sustain you forever, so you will have to get used to hunting and gathering your own food. Designate different people based on their strengths to search for food. Moving near the equator will be warmer and if the dirt is fertile, this will allow you to begin to grow food for consumption.
- Having more people in your group will allow you to search for food more effectively.
- Moving near a large body of water will allow you to fish.
- Use survival guides to determine what foliage is good to eat and what is poisonous.
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Create a governance system for your new society. A popular vote is a direct democracy and would work so that everyone had a voice in matters that affect the group. While having a final decision maker or leader is conventionally how smaller groups tend to act, having everyone’s voice be heard will hopefully ensure less fighting in your group.
- As your group gets larger, the governance system becomes more critical.
- Make sure to hold everyone to the same standards.

Community Q&A

Question

What happens if you have to use the bathroom?

Community Answer

Many shelters have bathrooms equipped with them that connect to a septic system. It's possible if you don't have a bunker that running water will stop working, so you can manually flush your toilet and fill it with buckets of water afterward.
Question

Will humans survive a comet impact?

Community Answer

If a 60 kilometer comet did make impact with the earth, all life on earth would be extinguished. If the comet was smaller, there's a good chance many people and other living things could survive.
Question

What percentage of us would survive?

Insaneroo1

Community Answer

It depends on how large the comet is and where it strikes, the percentage is impossible to calculate without knowing more about the strike.