If whatever hit Jupiter last week—and astronomers might never know what it was—had instead struck Earth, it would have caused catastrophic damage to human civilization.

Here’s how the New York Times describes it:
An object, probably a comet that nobody saw coming, plowed into the giant planet’s colorful cloud tops sometime Sunday, splashing up debris and leaving a black eye the size of the Pacific Ocean. This was the second time in 15 years that this had happened. The whole world was watching when Comet Shoemaker-Levy 9 fell apart and its pieces crashed into Jupiter in 1994, leaving Earth-size marks that persisted up to a year.
That’s Jupiter doing its cosmic job, astronomers like to say. Better it than us. Part of what makes the Earth such a nice place to live ... is that Jupiter’s overbearing gravity acts as a gravitational shield deflecting incoming space junk, mainly comets, away from the inner solar system where it could do for us what an asteroid apparently did for the dinosaurs 65 million years ago.
At the Institute for Ethics and Emerging Technologies we have four main program areas: Envisioning the Future; Longer, Better Lives; Rights of the Person; and Securing the Future. That last item is further described as “working to identify and advocate for global solutions to threats to the future of civilization.” Threats we’ve identified include pandemics, biohazards, nuclear or nano warfare, climate change, and yes, strikes from comets and asteroids.
It’s only a matter of time before another giant impactor comes our way. Fortunately, Jupiter is there to sweep up a lot of debris before it can reach the inner solar system and target Earth, but it can’t catch everything. If we hope to survive long as a civilization, we must make use of existing and emerging technologies to first find and then deflect the next planet killer before it gets here.