Discover the different ways our planet is being protected from asteroids and meteors.
 

On Demand Activities

Defending Planet Earth Introduction      Activity: Spot an Asteroid      Activity: Asteroid Impacts on Earth      Activity: Deflect an Asteroid      Spotlight Story      Story Time and Craft Activity      Explore Outside

Defending Planet Earth

What does it mean to defend our planet?

Asteroids, comets, and meteors - these are the objects in space that scientists at agencies like NASA and the Department of Energy keep an eye on to make sure we are prepared in case one of them threatens the safety of our planet.

The asteroids and comets that orbit the Sun like the planets and have orbits that come within 30 million miles of Earth’s orbit are called Near-Earth Objects (NEOs).

According to NASA's Planetary Defense Coordination Office, in May 2023, 10 near-Earth asteroids passed closer to the Earth than the Moon. In the past year there were 103 near-Earth asteroids!

Potentially hazardous asteroids are NEOs that are orbiting close to Earth and are larger than 100 meters (328 feet), which is the length of a soccer field. There are five potentially hazardous asteroids that have already been studied using space probes - Bennu, Didymos, Itokawa, Ryugu, and Toutatis. 

What is the difference between asteroids, comets and meteors?

A composite image showing a comet, an asteroid, a meteoroid, a meteor, and a meteorite.

A composite image showing Near-Earth Objects (NEO). 

A. Comet

A comet is a collection of ice and dust that orbits the sun. They sometimes have a tail of debris trailing behind them.

The comet in the image is Comet ISON. When this image was taken, it was some 44 million miles from the sun—and 80 million miles from Earth—moving at a speed of 136,700 miles per hour. 

B. Asteroid

An asteroid is a small rocky object that orbits the sun. They are smaller than planets, but larger than meteoroids. There is a large asteroid belt between Mars and Jupiter that contain hundreds of thousands of asteroids.

C. Meteoroid

A meteoroid is a piece of an asteroid, comet or planet that breaks off and travels in space.

D. Meteor

A meteor is the streak of light that appears in the sky when a meteoroid enters the Earth's atmosphere. We also call this a shooting star, but it's not actually a star at all! 

E. Meteorite

A meteorite is a meteor that has made it all the way down through Earth's atmosphere and landed on Earth's surface. This image shows NASA astronomer Peter Jenniskens with an asteroid meteorite found in the Nubian Desert of northern Sudan. 

How does NASA spot a Near-Earth Asteroid?

Activity: Spot an Asteroid 

This video is a loop of photographs taking by the National Optical Astronomy Observatory in Tucson, AZ. 

Watch the video. Can you spot the asteroid?

Look for a speck that is moving in a straight line, while everything else around it stays the same.

Activity: Asteroid Impacts on Earth

When asteroids enter the Earth's atmosphere or impact the Earth, they cause a lot of damage, which is why near-Earth objects and potentially hazardous asteroids are always being watched. Here are examples of evidence of asteroids near and on Earth:
 

A photograph of a streak of vapor in the sky over a snowy village.

Chelyabinsk, Russia

10 years ago

A meteor weighing 10,000 metric tons exploded 14 miles above Chelyabinsk, Russia, on February 15, 2013. The energy from the blast damaged more than 7,000 buildings in six cities. Approximately 1,500 people were injured mostly from flying glass from the windows that were shattered by the asteroid’s blast wave. 
 

Tunguska

Tunguska, Russia

115 years ago

An asteroid 50 meters across entered Earth's atmosphere and exploded above the surface of a forested area in Russia. The heat and energy from the asteroid flattened trees in a very large area of the forest.

The event happened in 1908 but scientists weren't able to study the site until 19 years later.

A picture of a crater in the desert.

Meteor Crater, Arizona

50,000 years ago

The Meteor Crater, which is about 3,900 feet (1,200 meters) in diameter and about 560 feet (170 meters) deep, was created by a 40 to 50 ton asteroid. 

The crater has been preserved well because of the dry desert climate.

 

 

An illustration of a green peninsula.

Chicxulub Impact, Yucatan Peninsula, Mexico

65 million years ago

This impact, which is buried partly underwater, was made by an asteroid 10 miles wide (14 kilometers). The impact is famous for its devastating effect on the Earth, which included the extinction of 75% of life on the planet, including the dinosaurs.

In this radar image of the Yucatan Peninsula, you can see the faint rim of the crater.

Make your own impact crater

(modified from NASA's Jet Propulsion Lab learning resource)

Gather these materials:

  • A container: This can be a Tupperware container, a cardboard box, an aluminum pie pan, or anything of a similar size and depth. It is recommended that glass containers not be used due to a breaking hazard.
  • Flour (or any light colored material, such as sand)
  • Cocoa powder (or a material similarly loose and dark, like glitter that is a different color from the above material)
  • 3 small rocks of different sizes (small, medium, and large) - or similarly shaped objects
  • Newspaper or other material that can be placed on the floor or table to protect it and make cleanup easier.
  • Ruler
  • Paper
  • Pencil
Step 1: Prepare your work area
  • Put newspaper underneath and around your impact crater making area! Material will fly out of the container during impacts so this will help with clean-up afterwards.
  • In the container, spread a 1-inch thick layer of flour (or sand) and then a thick layer of cocoa powder (or glitter).  The dark powder should be on top.  
    • Tip: You can use whatever loose material you may have available; you do not need to use food materials for this experiment. You may also include additional layers as long as those layers have a difference in color.
  • You will repeat these steps to make craters more than once, so make sure you have enough materials to do this twice.
What appears to be dirt or cocoa flour in a pan. The pan sits on paper towels, there are rocks.
Step 2: Drop your "asteroids"

Trial 1:

  • Take one of your rocks and hold it above your crater making area, about 2 to 3 feet high.
  • Drop it from above.
  • Measure the crater to figure out how wide it is.
  • What else do you notice about the crater you made? 

Trial 2: 

  • Try tossing your rock at an angle instead of from up above. 
  • Measure the crater across.
  • How is it different from the other crater you made?
A hand is poised above a bowl of brown material. The hand holds a rock.

This is an illustration for an activity that's part of the Soar Together on Planetary Defense. 

Step 3: Make observations and comparisons

What did you notice about the craters you made? What was different between the different rocks and ways of impacting your surface?
 

Brown flour-like substance in a silver bowl. There's a divet in the center.

This is an illustration for an activity as part of the Soar Together on Planetary Defense. 

Activity: Deflect an Asteroid

Part of the job of Planetary Defense is to come up with plans and ideas for what to do if there is an asteroid endangering Earth and test them out.

One of the tests that NASA has conducted is called the Double Asteroid Redirection Test (DART). The purpose of DART is to test out whether we could use a spacecraft to change the path of an asteroid.

An infographic showing an illustration of the DART spacecraft headed for an asteroid.

An infographic showing the asteroid Dimorphos in it's orbit, how the DART spacecraft will approach it and change it's orbit. 

The DART spacecraft was launched in November 2021, and impacted its asteroid target on September 26, 2022. NASA confirmed that the mission was a success and that they did in fact redirect the asteroid's path!

Check out the DART webpage for cool video of the actual impact.

People in blue polo shirts standing in front of computer clap and raise their arms in celebration.

Members of the DART team celebrate on September 26, 2022, as images livestreamed from the spacecraft show it successfully impacted the asteroid Dimorphos, completing the world’s first planetary defense test mission. 

Try it Yourself!

Create your own model of the DART mission and redirect an asteroid! 

What you'll need:

  • Three round objects of different sizes:
    • One large object to represent the Earth
    • One medium object to represent an asteroid
    • One small object to represent the spacecraft
  • A smooth, hard surface for rolling the round objects
  • Two players
One large soccer ball and one smaller soccer ball sit side by side.

This photograph illustrates an activity for our Planetary Defense Soar Together virtual family day. 

Step 1: 

Set up your play area like this image.

Step 2: 

Choose a person to play the role of the asteroid. The other person will play the role of the spacecraft. 

Two soccer balls sit in vertical line in a hallway.

 This photograph illustrates an activity for our Soar Together virtual family day on Planetary Defense. 

Step 3: 

Once everyone is ready, roll the asteroid ball towards Earth.

The spacecraft person will roll their ball towards the asteroid and try to deflect it.

Tip: It may take many tries to deflect the asteroid! Experiment with different speeds and angles.

Three balls sit in a hallway.

This photograph illustrated an activity for our Soar Together virtual family day on Planetary Defense.

Spotlight Story: Meet Dr. Kelly Fast, Planetary Defender

Dr. Fast's job is to find near-Earth asteroids, learn more about them, and share information so that agencies can plan for any potential hazards.

Let's Imagine: if you could create an asteroid awareness poster, what would it look like? Draw or write out your message!

Story Time and Craft Activity

Learn more about asteroids, meteors and comets, and listen to a story about a comet on a journey. Then do the craft activity and create your own telescope to look for the near-Earth objects!
 

Materials Needed: 

  • paper towel cardboard tube
  • tape
  • colored paper
  • scissors
  • crayons

Watch this video for the story and craft instructions.

Let's Imagine

  • If you saw a meteor or comet shining in the sky, how would you feel? Scared? Excited? Curious?

Explore Outside!

Celebrate Asteroid Day

Asteroid Day is a global event that happens every year on June 30, to mark the anniversary of the Tunguska event. The purpose is to build awareness around planetary defense and asteroids.

Find an Asteroid Day event near you. 

The text "Asteroid Day 30 June" over an illustration of an asteroid.

The logo for Asteroid Day

Observe a meteor shower

Meteor showers occur when the Earth’s orbit around the Sun takes us through a debris field. These debris fields are often made up of a trail of cosmic dust left behind by a comet. The millions of tiny particles can create a “shower” of dozens of meteors per hour.

The best way to view a meteor shower is to get away from bright lights and to a place with darker skies. 

Find a flat area with few trees or buildings, then lie back and let your eyes take in the whole sky. Any time a streak of light appears, your eyes will go right to it because you’ll sense the movement. 

You can find out when the next meteor shower will happen from the American Meteor Society with their weekly forecasts. 

Gather your skygazing supplies and enjoy the sight!

An illustration of the Sun in the center, the Earth orbiting horizontally around it, and a comet orbiting vertically around it.

An illustration of a comet and Earth orbiting around the sun. 

Linear sparks of light against a purple sky.

A shower of Perseid meteors lights up the sky in 2009 in this NASA time-lapse image.

Soar Together at Air and Space is made possible by the generous support of Northrop Grumman.

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