Light year is not a unit of time, as you would think, judging by his name. Light year is a unit of distance, accepted in astronomy.
Celestial distances are difficult to measure in conventional meters and kilometers - so they are huge! Light year is the distance that passes a beam of sunlight per year, that is 365 days. But the speed of the light beam is almost 300 thousand kilometers per second! Therefore, the light year is equal to 9460800000000 km, that is about 10 trillion kilometers. So much easier, for example, say the brightest in the sky the star Sirius removed from us at a distance of 8 light years.
At first glance, this unit may seem inconvenient. But actually it is very comfortable its visibility. For example, the distance measured in light years, clearly shows what stars you can send radio or other electromagnetic messages to get an answer in real time, and not through hundreds and thousands of years.
Did you know that...
- The average distance to the moon is approximately 376 300 km. Means, a light beam sent from the Earth's surface, you will need to 1.2-1.3 seconds to reach the surface of our natural satellite.
- Our nearest star, not counting the Sun, Proxima Centauri, is located at a distance of 4.22 light years from us.
- The diameter of our galaxy, the milky way is 100,000 light years
- Our nearest spiral galaxy is the famous Andromeda galaxy-removed from us at 2.5 million light years.
