We're lucky enough to live on a planet where it's comparatively easy to design and build aeroplanes that work: our atmosphere and the Earth's gravitational pull are kind in that respect. But what would happen if you tried to fly a regular plane around another planet or moon?
As Randall Munroe points out in a new What If? post, in most cases, not a lot: there's no atmosphere on plenty of those celestial bodies, so a plane would fall straight out of the sky. On the few that do have an atmosphere — including Mars, Venus, the four gas giants, Saturn's moon Titan, and the sun — it's more difficult to say.
So Munroe took to X-Plane, a highly tweakable flight simulator which accurately models flight physics in-game. It's so tweakable, that it can simulate flight on other planets. So... that's what Munroe did. His results, which you can read over on What If?, are entertaining:
Our Cessna can't fly on Jupiter; the gravity is just too strong. The power needed to maintain level flight is three times greater than that on Earth. Starting from a friendly sea-level pressure, we'd accelerate through the tumbling winds into a 275 m/s (600 mph) downward glide deeper and deeper through the layers of ammonia ice and water ice until we and the aircraft were crushed. There's no surface to hit; Jupiter transitions smoothly from gas to solid as you sink deeper and deeper.
But there is one piece of good news. On Saturn's moon, Titan, a relatively low surface pressure and insanely low gravitational pull (weaker than our moon's), means even a pedal-powered plane could take off. You can — and should — read the whole post over on What If? ... and then maybe take a flight to Titan. [What If?]