What must an earthly spacecraft exit for its travel to be interstellar?
Interstellar travel Interstellar travel Interstellar travel is the term used for crewed or uncrewed travel between stars or planetary systems. Interstellar travel will be much more difficult than interplanetary spaceflight; the distances between the planets in the Solar System are less than 30 astronomical units (AU)—whereas the distances between stars are typically hundreds of thousands of AU, and usually expressed in light-years. Because of the vastness of those distances, interstellar travel would require a high percentage of the speed of light; huge travel time, lasting from decades to millennia or longer; or a combination of both. The speeds required for interstellar travel
Interstellar travel less common, but would be much more destructive. The risks of impacting such objects, and methods of mitigating these risks, have been discussed in the literature, but many unknowns remain and, owing to the inhomogeneous distribution of interstellar matter around the Sun, will depend on direction travelled. Although a high density interstellar medium may cause difficulties for many interstellar travel concepts, interstellar ramjets, and some proposed concepts for decelerating interstellar spacecraft, would actually benefit from a denser interstellar medium. The crew of an interstellar ship would face several significant hazards, including the psychological effects of long-term isolation, the effects of