Don’t judge space junk’s potential for destruction using your Earthly instincts: Traveling at tens of thousands of miles per hour in space, even a small object has the potential to inflict major damage. In one incident that demonstrates that fact of physics, a 2mm piece of space once junk put a 5cm-wide dent in a climate satellite. A modest move up the scale brings much more power: “A one-centimeter piece of debris has the energy of a hand grenade,” ESA’s Tiago Soares told DW.

In an ominous 2009 incident, a Russian Cosmos satellite collided with an Iridium satellite, creating a cloud of about 2,000 pieces of junk measuring 10cm or more. That’s brings us to the nightmare scenario that should fill you with dread: The Kessler Effect. Imagine an initial major impact that creates hundreds of shards, which then start colliding with more orbiting objects, setting off a chain reaction. Actually, you don’t need your imagination. While some scientists say it wasn’t fully accurate in depicting the physics, Hollywood ventured to depict the Kessler Effect in the 2013 movie, Gravity: