Malaysia Airlines flight MH370 disappeared somewhere over the Pacific or Indian Ocean almost a week ago, but so far no sign of any wreckage has been found.
At first it might seem like that fact just doesn't make sense. As others have said this week, how can a modern airliner with GPS trackers, communications equipment and a "black box" recorder just go missing - especially when NASA and the internet at large are on the case?
Because the ocean is big.
We're talking an area 160,000 miles square. Which, when zoomed out to the width of this post, is almost invisible.
To get the full effect, head over to the Washington Post website.
If you're interested in trying to help check out our post explaining how you can try to do just that here.