Hi, I’m Marley, the Astronomer here at the Space Centre.

Asteroid day, June 30th, marks the anniversary of the 1908 explosion of an object (probably an asteroid) over Siberia and I’ve been doing a bit of thinking about how much we can learn from them and what they mean to us in terms of safety. I can’t even begin to count how many times I’ve seen a disaster movie about a giant space rock hurtling towards Earth, and how humanity faces that challenge. What about real life? Are we watching out for space rocks? What is our plan if one gets too close?

First, some definitions. An asteroid is a rocky remnant from the formation of our solar system, ranging in size from 10m - 530 km across. What we first think of when we think of asteroids is the one that left behind the Chixulub crater and really ruined the day for a lot of dinosaurs. But it turns out that the object that left behind that crater may not have been an asteroid at all, but instead a comet.

Comets are also remnants from the formation of the solar system, but the difference is that they are “dirty snowballs” made up of ices, rocks and dust instead of just rocky materials. The frozen part, called the nucleus, is normally no more than a few tens of kilometres across.  Comets are well known for their tails, formed from dust and gas released by the melting comet as it approaches the Sun. 

If parts of a comet or an asteroid break off, the little pieces are called meteoroids. These small space rocks only become meteors when they enter the atmosphere. They are called meteorites if they make it all the way to the ground. So, the object that ruined the dinosaur's day about 65 million years ago would be called a meteorite, but there is still some debate on whether or not its origin is an asteroid or a comet.
Asteroids, comets, and meteoroids can all pose a risk to Earth. The good news is that scientists have been looking out for them in a variety of ways.

Canada has two different research activities looking at meteoroids, both based out of Western University. The Canadian Meteor Orbit Radar (CMOR) detects and gathers information about meteoroids. CMOR is able to detect meteoroids a mere 0.1mm in size and has measured the orbits of 4 million individual objects! The All-Sky Camera Network  automatically detects fireballs (exceptionally bright meteors) and records the data about them. The data gathered in one such event helped the Western Meteor Group determine how much energy a meteorite deposited when it landed in Botswana in 2018. This information  allowed the team to estimate the original size and mass of the asteroid!

We can study the smaller meteorites that we can find, and track the orbits of objects, but what can we do if one such object is on a collision course with Earth? An upcoming NASA mission is going to test one method of defense: asteroid redirection. The Double Asteroid Redirection Test, or DART, is an upcoming test of technology. The spacecraft will go to the binary asteroid system Didymos. Two asteroids make up this system: Didymos, which is 780 meters in diameter, and the smaller asteroid that orbits it, Dimorphos, 160m in diameter.  This system is an ideal one for the test. The spacecraft will hit the smaller asteroid, Dimosphos, at approximately 6.6km/s, hopefully changing its orbit around Didymos. Scientist on Earth will be able to measure the change in the smaller asteroid’s orbit. This asteroid pair are not on a collision course with Earth at all so there is no threat! If it works, this science can possibly be applied to large bodies that may hit Earth. If only the dinosaurs had this technology.

I hope this inspired you to think more about asteroids, comets and meteoroids. Check out some of the activities below to learn more!

Astronomers Playlist

Read more about the different kinds of space rocks.
Ask yourself: What category of space rocks do you find most interesting?


Use NASA’s Eyes on the Solar System interactive to travel to comets and asteroids. Use the search feature and type in asteroid or comet and then choose from the list to pick your destination.
Ask yourself: What did you notice about the location of the asteroids and the comets within our solar system?


Make some popcorn and watch a movie about how humans respond to the impending threat of an asteroid or comet. This article in Space.com reviews some classics and read this review about the movie Greenland.
Ask yourself: What do you think about the way the science and scientists were portrayed in the film you watched?


The OSIRiS-REx is heading back to Earth with a sample of the asteroid Bennu. Just how hard is it to grab a sample of an asteroid? Watch this short video to find out.

Now try your hand at collecting a sample. Visit this page and see if you can build a device to take a sample from a potato “asteroid”. Then use your potato to make your own asteroids (ask an adult to help).

Listen to planetary scientist Hannah Kaplan talk about her work on the OSIRIS-Rex mission.

Ask yourself: What do you think would be the most challenging part of planning a mission like OSIRIS-Rex?



Watch this interview with Masaki Fujimoto from the Japanese Space Agency about Japan’s Hayabusa 2 mission to the asteroid Ryugu and the return of the samples collected.
Ask yourself: What do you think they will find when they begin to analyze the samples from Ryugu?



Find out more about the recent Rosetta mission to comet 67P with this fun animated video. Even though the Rosetta mission is over scientist keep making new discoveries with the data collected. Find out more about some of the recent discoveries about this comet.
Ask yourself: How do you think the information learned about comet 67P will compare to what we learn about asteroids Ryugu and Bennu?



Find out about micrometeorites, tiny meteorites that might be on your roof and how you might be able to collect them. Please be careful if you are climbing on roofs!
Join Zooinverse’s Radio Meteor Zoo project and help scientists identify meteors in data collected from radio waves.
Ask yourself: What did you find most challenging about trying to collect micrometeorites?