This is the most common questions that people make you at moment they learn that you're a scientist.

For some reason is enough say that you are graduated in physics for all those who are in the room have the collective thinking that you know everything.

And certainly not is it ... (I wish I knew all ... would win millions in bets).

Today our beloved blog of physics we have another recreational post! like Discovery Channel 90's that left you with the feeling that you knew something very important about science!

We will answer the questions posed by parts thus explaining step by step, starting from the most basic thing is: The lightyears is a distance measure not time.

Poow! first left hook to the chin ! the common denominators to hear "year" refers to believe that is a time magnitude.

Already at this point we feel that know something new and super important scientific thing!. Let's read more for that feeling increases !.
Another small step in answering the question of what is a lightyear? It is formally definition: A lightyear is the distance light travels in vacuum in one year's time (about 9 trillion kilometers).

That's the formal definition of light year. But what we refer to say -speed of light- ?.

The speed of light is a constant (time-invariant and invariant under transformations of coordinate systems). It has a fixed value of 2.99x10 ^ 8 m / s.

It is faster than Goku! can turn around the world 8 times in one second ...
In our everyday world we manage meters and kilometers (one kilometer is thousand meters 1x10 ^ 3m = 1km).

Why?

At least you live in a region where the English System is handled yards and miles.

Most countries use the international system (with meter as its unit of distance), this is because we defined the meter as the distance light travels in vacuum for 13 millionths of a second.

We see as understanding the lightyear concept? like meter the lightyear is defined as a distance travel by light in a given time, for the meter this time is 13 millionths of a second, for lightyear is a year (about 3.154x10 ^ 7 seconds).

Why we use the lightyear ?. If I tell you the nearest hospital to your new home is 100m you want to live there ? most likely the answer is yes ..

And if I say that is 100km ? most likely the answer is no. We understood those numbers 100m and 100km. By contrast ..

In the world of astrophysics everything is near the kingdom of Princess Fiona namely far far away.

Distances are something like 9 trillion kilometers (about 6 trillion miles as minimum) these figures are very long to write, very annoying to handle and truly incomprensiobles, for this reason we uses the light year since it is easier to say one lightyear distance (1 lyr) to say 9 trillion kilometers.

To give you an overview of everything that we say. A lightyear is a unit of distance. It is the distance light travels in a vacuum during one year of time. They are about 9 trillion km. It is common used in astrophysics.

We finish our post with a curiosity !. A photon (the form of particle of light) takes about 8 minutes to get from the sun's surface to the surface of the earth.

These are the kind of comments that you say when a group conversation is muted for a couple of minutes. It is great for breaking the ice!
This was all in this post... if you like our work share it with your friends! see you later! and remember ... physics it's easy! very easy... ;)