The speed of light in vacuum, is a universal physical constant that is important in physics. Its exact value is defined as 299,792,458 meters (983,571,056 feet) per second. That translates to just about 186,282 miles per second.
A light-year – the distance light travels in one year – is about 6 trillion miles (10 trillion kilometers). To put that in perspective, light from the sun (about 93,000,000 miles away from us) takes about 8 minutes to reach our eyes, so the sun has set about 8 minutes before you actually see the sunset!
Light from Alpha Centauri, the nearest star system to our own, takes about 4.37 years to get here – that’s over 43 trillion kilometers away, if you’re doing the math (or just over 26.7 trillion miles).
In today’s terms, if we launched the most powerful rocket currently known to humans here on planet Earth, it would take about 80,000 years to reach Alpha Centauri.