The asteroid that almost wiped out life on Earth - Sean P. S. Gulick

Let’s explore the effects of impacts on Earth by using some online tools. Astronomers track Near Earth Objects (NEOs) in order to calculate the sizes of the asteroids or comets, as well as the chances of an Earth-crossing orbit. A NASA-updated list of NEOs and their cumulative probability of striking Earth is available here, and it shows how most NEOs are quite small. However, there are some larger ones, such as the asteroid Bennu, that are certainly worth tracking. But how do we know the effects of differently sized asteroids if they were to strike Earth? It turns out it depends on a lot of factors, including the size, speed (velocity), density of the asteroid, and what part of Earth it hits (assuming it does not burst in the atmosphere), among many others. 

To explore these possibilities, you can use the Earth Impacts Effects program, available here. You can enter the distance from which you are observing an impact (e.g., 100 km or 60 miles from the impact, the effects I would feel are…), the diameter and density of the asteroid, the velocity of the object, the angle at which it hits, and finally, what the target area of Earth is made of (e.g., ocean or lake of a specific depth, sedimentary rock like limestone or sandstone, or crystalline rock like granite or basalt). 

As an exercise, try entering some of the asteroids from the SENTRY table into the Earth Impact Effects Program, including their density and velocity (find these by clicking on the name of the asteroid), and then have them hit different types of targets on Earth to explore the effects. Some questions that might come up are: How big does an asteroid have to be to actually hit the ground? Do the effects get worse if the density of the asteroid is greater? Does the angle at which the asteroid hits matter? What effects change if the asteroid hits water as opposed to land made of sedimentary or crystalline rock? What kinds of energies are released in your different impact scenarios (Hint: these can be very large numbers!)? Lastly, look at the probabilities in the SENTRY table to realize how incredibly small the chance of a major impact in the next couple centuries is—and to perhaps breathe a sigh of relief. 

Have fun exploring and learning!

Images and references used in the creation of this animation:

Pixabay - Stock Images:

Sunflower - RayMark

Grass - Hundankbar

garbage - ds_30

Iceberg - Makabera

Polar bear - iribagrova8176

Paintings in the public domain:

Starry Night - Vincent Van Gogh

The Great Wave - Katsushika Hokusaï

Eiffel Tower - Georges Seurat

Black Mesa - Georgia O'Keeffe

Guernica - Pablo Picasso

Skrik & Solen - Edvard Munch

The Great Day of His Wrath - John Martin

The Slave Ship - William Turner

Sketchfab - All Sketchfab models are licensed under Creative Commons attribution (CC BY 4.0):

Triceratops - Zacxophone

Carnotaurus - Magorius

Tyrannosaurus Rex - Rigsters

Temple - Maks Sokolowski

Human skeleton - Ruslan Gadzhiev

Mouse - Just8

Saberwing - MooreLab

Frog - ffish.asia / floraZia.com

Rhododendron - ffish.asia / floraZia.com

Tsukushi Rose - ffish.asia / floraZia.com

Orchid - sarahGB

Wood stick - 3dhdscan

Wood louse - .hapto GmbH

Bush - Marbles

Lichen - Frank McMains

Aloa Vera - nedo

Lab - viklia

Lab gear - dercruz926

VHS - Terrible Hard

Old computers - sudreyskr

Lab machine - guillemvilah

Floppy disk - ocean

Machine - Klinepeter

Mission control console - TheoClarke

Old computer - Freepoly.org

Old nuclear computer - P3TroV

Osborne - Denis Afanasjev

vintage terminal - NoMoreFeelings