the most advanced spacecraft that humans have developed are not capable of traveling anywhere close to the speed of light. Therefore, it would take a significant amount of time for a spacecraft to travel one light-year, which is the distance that light travels in one year, approximately 9.46 trillion kilometers (5.88 trillion miles).
Currently, the fastest spacecraft ever launched by humans is the Parker Solar Probe, which was launched in 2018. Its mission is to study the Sun and its outer atmosphere, known as the solar corona. The Parker Solar Probe will achieve speeds of up to about 430,000 miles per hour (700,000 kilometers per hour) as it gets closer to the Sun. However, even at this impressive speed, it would take the Parker Solar Probe tens of thousands of years to travel one light-year.
To give you an idea of the immense challenge of interstellar travel, our current technology and understanding of physics would need significant advancements to reach speeds that could make interstellar journeys feasible within human lifetimes. Concepts such as ion propulsion, solar sails, or even theoretical ideas like warp drives are being explored as potential means to achieve higher speeds in the future. However, these technologies are still in the realm of scientific exploration and development.
It's worth noting that the Breakthrough Starshot initiative, announced in 2016, aims to develop spacecraft that could reach nearby star systems within a human lifetime. The proposed technology involves using laser-powered light sails to accelerate tiny spacecraft to a significant fraction of the speed of light. However, this is a concept under active development and faces many engineering and technical challenges.
In summary, our current spacecraft technology is far from being capable of traveling one light-year within a reasonable timeframe. Achieving interstellar travel speeds that would make such journeys feasible will require significant advancements in propulsion systems and a deep understanding of the challenges associated with long-duration space travel.