Caelum Incognitum — The interactive encyclopedia of ufology
Interstellar distances
Hypotheses & theories
The nearest star, Proxima Centauri, is about 4.2 light-years away. With known technology, a journey would take thousands of years. It is one of the main skeptical arguments against the extraterrestrial hypothesis, hence the interest in proposals for other means (automatic probes, unknown technology).