How big is the comet in Deep Impact?

So, How Big Was That Comet We Punched? The Scoop on Deep Impact’s Target

Back in 2005, NASA pulled off something pretty wild: they slammed a probe right into a comet! It was called the Deep Impact mission, and the whole point was to see what Comet Tempel 1 was made of by, well, impacting it. But to really understand what happened, you gotta know: how big was this space snowball, anyway?

Comet Tempel 1, or 9P/Tempel 1 if you want to get official, wasn’t exactly a behemoth. Think of it more like a lumpy potato than a perfect sphere. Because of that odd shape, pinning down an exact size is tricky. But scientists reckon it was roughly 7.6 km by 4.9 km – that’s about 4.7 miles long and 3 miles wide. Another estimate puts it at around 14 km long and 4 km wide. To keep it simple, you could say it was about 6 kilometers across. That’s only half the size of the rock that likely wiped out the dinosaurs! Pretty small in cosmic terms, right?

Now, figuring out the size of a comet isn’t a walk in the park. They’re usually hiding behind a cloud of gas and dust, called a coma, which makes it hard to get a good look at the actual nucleus, the solid part. So, scientists have to use all sorts of tricks, like telescopes on Earth and in space, to try and get a handle on its dimensions. It’s like trying to measure a fuzzy object in the dark!

The Deep Impact mission itself helped a lot. Sure, the impact kicked up a ton of dust that made it hard to see anything at first. But later on, in 2011, another mission called Stardust-NExT swung by for a follow-up visit. This time, they got a good look at the crater we’d made. Turns out, it was about 150 meters across – that’s like a giant football stadium-sized dent!

Knowing how big Tempel 1 was is super important. It helps us understand what Deep Impact taught us, and it helps us figure out what might happen if a comet ever decided to pay Earth a visit. Gives you something to think about, doesn’t it?