How Long Does it Take to Travel 1 Lightyear at the Speed of Light?

Traveling at the speed of light, it would take one year to traverse a single lightyear. This is because time appears to stand still in its own frame of reference. However, for us humans, it would take considerably longer than a year to cover the same distance. To put this into perspective, there are approximately 31,500,000 seconds in a year.

Multiplying this by 186,000 (the distance light travels every second) gives us 5.9 trillion miles (9.4 trillion km) - the distance light travels in a year. The concept of the speed of light was first discussed by the Greek philosopher Aristotle, who believed that light traveled instantaneously. For someone traveling at the speed of light, a journey of one lightyear or even a billion lightyears would seem to pass in an instant. On a spaceship, time passes differently so the traveler wouldn't even feel like they were moving and the journey would be over in less than a second.

If a spacecraft were traveling at the same speed as Helios 2, it would take 4269 years to travel one lightyear. This spacecraft was carrying two astronauts and had an average speed of 28,163 kilometers per hour. Experiments have shown that time passes differently when traveling at the speed of light. However, for someone on board a spaceship traveling at this speed, time would not pass in the same way as it does outside the ship.

The speed of the spacecraft depends on its orbital altitude which is usually between 304 kilometers and 528 kilometers above sea level. If a spaceship were to travel at one lightyear per year, it would cover the distance of one lightyear in a human year.