Theoretically, you could drive to space in about an hour.
Space stretches out in all directions (at least as far as we can tell) for some 46 billion light-years, but it doesn’t take all that long to get to where it begins. In fact, if you had a car that could somehow drive skyward toward the Kármán line — the barrier that marks the beginning of space — you’d arrive there in little more than an hour (and that’s while cruising at a leisurely 60 mph). The Kármán line, named after Hungarian American physicist Theodore von Kármán, was set by the Fédération aéronautique internationale (FAI), a world governing body for air sports, and exists at 62 miles above sea level.
But Earth’s atmosphere doesn’t just abruptly end — it slowly fades away, making the definition of “space” a bit murky. NASA, for example, classifies anything 50 miles above sea level as space, even though the outermost layer of the Earth’s atmosphere, the exosphere, stretches much farther. In fact, the International Space Station (ISS) actually travels within the Earth’s thermosphere (the layer below the exosphere), at about 250 miles above sea level. But just because these areas are part of the Earth’s atmosphere doesn’t mean they can’t be considered space. Air density in the thermosphere and exosphere is so low, most agree that these regions contain essentially the same conditions as space. If you wanted to take your hypothetical space car completely beyond Earth’s atmosphere, all the way to the region known as “outer space,” it’d be an epic road trip to the end of the exosphere, some 6,200 miles from Earth.
The ozone layer in the Earth’s atmosphere protects all life on Earth from harmful UV radiation. Without it, life on this planet simply wouldn’t be possible. The ozone layer is so important — and so fragile — that when scientists discovered a hole in the ozone layer over Antarctica in 1985, the world sprung into action to restrict the use of aerosols containing chlorofluorocarbons, or CFCs. Although described as a “layer,” the ozone is actually spread throughout the lower atmosphere, reaching peak concentrations around the 16-mile altitude mark. The ozone is measured using Dobson units, named after Oxford University meteorologist Gordon Dobson, who devised a method to measure ozone in a column of air if it was squeezed into a single layer. At 300 Dobson units, the ozone layer would measure about 3 millimeters (a thickness of about two pennies) if squeezed into a layer under sea level pressure. You, me, and every living thing on Earth — past, present, and future — owe our existence to this small-but-mighty atmospheric shield.
