Traveling a light-year depends entirely on the speed of the traveler, since a light-year is a measure of distance, not time. A light-year is the distance light travels in one year, approximately 9.46 trillion kilometers (or about 5.88 trillion miles)
- At the speed of light (about 300,000 km/s), it would take exactly one year to travel one light-year, by definition
- Current human spacecraft travel much slower. For example, NASA’s Voyager 1, traveling at about 61,000 km/h, would take over 17,000 years to cover one light-year
- A typical crewed spaceship speed (around 39,400 km/h) would require about 27,000 years to travel one light-year
- For comparison, a commercial airplane at 965 km/h would take roughly 1 million years to travel a light-year, a car at 90 km/h about 12 million years, and walking at 5 km/h would take about 216 million years
In summary, with current technology, traveling a light-year would take tens of thousands of years or more. Only at light speed would it take one year, but this speed is currently unattainable for any spacecraft
