It is already one of the biggest films to hit cinemas this year, and if you haven’t seen Avengers: Age of Ultron yet, then I urge you to go and see it. Not only is it a brilliant action film, there is also a fantastic piece of space science involved in the plot line that I absolutely loved.

From here on out there will be spoilers for Avengers: Age of Ultron, so if you haven’t seen it yet, do not read on until you have. For those of you, who have seen it, please read on.

"Avengers Assemble in Armagh!" (Image credit: Colin Johnston/Armagh Planetarium. Superhero figures courtesy of Clarice Johnston)

“Avengers Assemble in Armagh!” (Image credit: Colin Johnston/Armagh Planetarium. Superhero figures courtesy of Clarice Johnston)


If you don’t know who the Avengers are by now, they began back in the 1960s in the page of comic books published by Marvel Comics as temporary team up of superheroes but are now a permanent group dedicated to protecting the Earth from apocalyptic threats. In the current movies, the team is Black Widow, Captain America, Hawkeye, Hulk and Iron Man. More heroes were added to the Avengers in this film, but I will let you discover them for yourself. The antagonist in the current movie, is Ultron, the powerful artificially intelligent robot created by Iron Man, originally created with the goal of “protecting the Earth”. What could go wrong with that?

On to the reason why I loved this film, here comes some major spoilers, so you have been warned.

Ultron, seeks to save the Earth from the thing that is harming it the most, human beings. How does he choose to do this? By creating an extinction event comparable to the one that ended both the Cretaceous Period and the dominance of the non-avian dinosaurs of course!  I thought to myself “how is Ultron going to be able to pull down a big enough meteoroid from space to do the damage that he wants to do?” Our question was answered not long after. Ultron decides to make his own meteoroid! How? Being a super intelligence, Ultron undermines a fictional eastern European town, installs antigravity devices, and with a controlled explosion, the malicious machine sends the whole area skyward. A piece of the Earth roughly the size of Deimos is ascending and when it is high enough this artificial asteroid will be released to smash into our planet’s surface. Humanity will be destroyed. Can the Avengers save us?

The day the dinosaurs died. (Image credit: Don Davis/NASA)

The day the dinosaurs died. (Image credit: Don Davis/NASA)


So what is the science behind Ultron’s scheme? In the film Ultron is fascinated with the impact that allegedly killed the dinosaurs. We say “allegedly” as the topic of what killed the dinosaurs is still hotly debated although this theory, which was first proposed by Luis Alvarez (1911-88) and his son Walter (b1940), is widely more accepted now than it was 30 years ago. The Chicxulub crater, which is in the Yucatán Peninsula in Mexico, is the site of the impact crater of the asteroid that is said to have killed the dinosaurs. It is estimated to be 106 – 186 miles in diameter, and if this can be proved it will ultimately be the largest impact crater on Earth. It has been estimated that this crater was created by an object roughly measuring 6 miles across (roughly the size of Deimos in fact), and the impact would have released as much energy as nearly 100 trillion tonnes of TNT. You may be thinking that this lets us know that the artificial impactor created by Ultron would have need to be at least six miles across, if not more, if he wanted to do the same type of damage, but it is not quite that simple.

What makes a meteorite a meteorite? Can a manmade meteorite actually be called a meteorite? In space we have meteoroids. They become meteors (or shooting stars) when they come into contact with the Earth’s atmosphere, this is what causes the streak of light across the sky. If the debris from the meteor makes it to the Earth’s surface is then called a meteorite. Tonnes of space debris falls to the Earth each day, but usually they are too small to even tell that they are in fact meteorites, falling unnoticed as dust.

Now we know the difference between a meteoroid, a meteor and a meteorite, the big question now is can we call what Ultron made, a meteorite? Technically it’s not something that has come from space, but would act like something that had. The propulsion system that he installed to lift his doomsday meteorite from the town lifts it further and further into the sky. From what we can recall from brief mentions of it in the film, the manmade meteorite made it to somewhere near the top of the stratosphere and the very beginning of the mesosphere. This is only our guess, we may be wrong, it is equivalent to an altitude of 50 km and is higher than any jet aircraft can attain. Up there the air is so cold and thin that conditions are pretty similar to those on the Martian surface. But is this high enough to call this an actual meteorite?

Shooting stars often occur around the bottom of the thermosphere and top of the mesosphere (about 90 km above the surface), so maybe if Ultron’s “meteoroid” had risen further up into the atmosphere, we could have maybe called it a proper meteorite except…

A falling meteroid has a speed relative to the Earth in the range 11-40 km/s. Let’s imagine Ultron’s doomsday rock was meant to fall from 100km up. It’s easy to calculate that its impact speed would be about 1.3 km/s. Now the kinetic energy released on impact is proportional to the square of the speed, so the impact might at best have a destructive potential one percent of the Chixculub impactor. That would be awesomely devastating but probably not quite a civilisation-ending disaster.

Barringer Crater, Arizona (image credit U.S. Geological Survey)

Barringer Crater, Arizona (image credit U.S. Geological Survey)

Naturally the Avengers manage to stop Ultron’s evil plan, and manage to prematurely detonate his “meteorite”  before impact, ultimately saving the entire human race from extinction. You never do find out where all the falling bits of landscape make their impact.

So what would have happened if Ultron’s “meteorite” had worked, and the Avengers could not stop him? Well, he would have got it to the highest point in the atmosphere as possible and then it would have been hurled back towards Earth with its own inbuilt propulsion system. The impact would have caused absolute devastation, with energy being released that would have equaled that of 1 trillion tonnes of TNT going off…or more! Millions of lives would have been extinguished but thanks to the Avengers the human race is safe…

(Article by Heather Taylor, Education Support Officer)

…until 2018 when Thanos shows up in person.


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