What have Queen guitarist Brian May, Apollo 9 astronaut Rusty Schweickart and filmmaker Grig Richters all got in common? (No, this is not the start of a bad joke.) They are all co-founders, along with Danica Remy from the B612 Foundation, of Asteroid Day.
Asteroid Day aims to raise awareness of the importance of asteroids in the formation of the solar system, and also the importance of defending our planet against future large impacts. The date, 30 June, was chosen because one of the largest, fairly recent, impact events occurred on that date in Siberia in 1908, known as the Tunguska event.
Although most asteroids come nowhere near us, there are a number of asteroids that have Earth crossing orbits, and those are the ones we have to watch out for. This is particularly true if they are more than a few metres in diameter, where they make it through the atmosphere to impact with the Earth.
For GCSE and A level Physics, you can do some fairly simple calculations to show the energy of these impacts. Asteroids travel at around 20 km/s. Depending on their type, they may have a density of between 1 and 6 g/cm3. So we can find the mass, and use the formula for kinetic energy to calculate the energy of the impact. It’s a good opportunity to practice unit conversion and deal with some big numbers. If you want to try a quick simulator for impacts then chek out this impact calculator.
The impact that caused the mass extinction 65 million years ago, including the death of the dinosaurs, was from an object of around 10km in diameter. With this kind of impact it is not so much the initial blast that is the problem - but rather the years of reduced sunlight caused by the dust and soot injected into the stratosphere.
If you want to look at this from a biology perspective, then there are some great activities in this STEM Clubs resource. This focuses on the aftermath of a large impact, with investigations looking at acid rain, and reduced sunlight in terms of the effects on power generation, photosynthesis and extremophiles.
Still, it’s not all doom and gloom. The likelihood of a really large impact is very small, asteroids are already tracked and efforts are underway to improve our capability to steer them off course if we do find out one is on the way.
I’d really like to hear if you try out any of the activities that I mentioned or if you have other ideas for Asteroid Day. There’s also a live event that you can find out more about by going to the Asteroid Day website here.