Outer space is generally considered to begin at the Kármán line, which is about 62 miles (100 kilometers) above Earth's surface. This boundary is widely accepted as the point where Earth's atmosphere becomes too thin to support aeronautical flight and where space begins
. However, the exact altitude is somewhat debated. Some research suggests the boundary could be as low as 50 miles (80 kilometers), based on satellite orbital data and atmospheric conditions
. The U.S. military and some scientists consider the lowest sustainable orbit to be around 90 to 150 kilometers (56 to 93 miles), which also influences where space is defined to start
. In summary, the most common and internationally recognized definition places the start of outer space at approximately 62 miles (100 kilometers) above Earth’s surface, known as the Kármán line. This is the altitude where the atmosphere is so thin that conventional aircraft cannot generate enough lift, and spacecraft begin to orbit Earth
