Help me understand this.
 

Can someone explain this definition to me?

Main Entry: par·sec
Pronunciation: 'pär-"sek
Function: noun
Etymology: parallax + second
: a unit of measure for interstellar space equal to the distance to an object having a parallax of one second or to 3.26 light-years

I know it should probably be easy, but I'm just not catching it?

Hold a finger in front of yourself, and look at it with one eye and then the other. It will appear to move. That is parallax.

Similarly, stars appear to move when looked at from one end of the earth's orbit versus half a year later on the other side of the sun. There's more of a motion the closer the star is.

One parsec is the distance to a star that will move one arcsecond on the sky (1/3600 degree) over the earth's orbit.

failing that, watch star trek.

didn't know about the parralax thing though, learn something new everyday.

And, as the definition also notes, that distance happens to be equal to 3.26 light-years.

wow i learn new things everyday

COOL

Damn,Go stingc,I had an idea but no way to explain it whatsoever.
Tfp totally helps me to learn new things all of the time.
Meow.

My favourite resource for space related knowledge is the Starchild website.

The Starchild explanation of a light year for kids (but still too long to cut & paste):-

http://starchild.gsfc.nasa.gov/docs/...uestion19.html

Parallax effect. Man something from astronomy coming into use!