I love this question!<p>Something appears to be weightless when it is falling the same speed as everything around it. If you took a kitchen scale, taped a weight to the top, and dropped them, you&#x27;d notice it appears to have a weight of zero.<p>On the topic of falling, if you walk off a cliff, you fall to the base of the cliff. If you run, you fall farther way. The faster you go, the trajectory of your fall will be farther from the cliff. Now go really fast and you may fall miles away - but you&#x27;ll be fighting air resistance and eventually slow down and hit the ground.<p>Above the Karman Line (62mi&#x2F;100km up), the air is thin enough that there barely any air resistance. If you go fast up here, the air isn&#x27;t there to slow you down. Gravity still pulls you back to earth though. [Blue Origin]<p>Now if you&#x27;re above the atmosphere and going horizontally fast enough, the trajectory of your fall eventually overshoots the curvature of the earth. Follow that trajectory a quarter rotation around the earth -- you&#x27;re still in space, you&#x27;re still going fast, and you&#x27;re still falling. You&#x27;re in orbit. (SpaceX)<p>Since you&#x27;re falling forever and the space station around you is also falling, you appear to be weightless in relation to the space station.<p>(The indie game Kerbal Space Program is a great way to play with&#x2F;explore the concepts of orbital mechanics if you&#x27;re intrigued.)<p>[Edit: For reference, the different in thrust needed to go straight up and coast to the Karman line compared to going up at an angle (spending more time traveling through the dense atmosphere) and establishing a horizontal speed of about 17,500 miles per hour is very big. I believe it&#x27;s at least an order of magnitude though I don&#x27;t have a citation for that number.]