Glory of the Sky

The Milky Way over a hut in the highlands of Gilan in Iran.

The night sky acts like a "time machine" because light travels through the universe at a finite speed and does not reach us instantaneously from any distant point. In fact, we stare at the stars and galaxies and watch their past.

For example, when it is said that a galaxy is 13 billion light years away from the earth, it means that it took 13 billion years for the light of this galaxy to reach the observer. In fact, when the light of this distant galaxy was released, neither the earth nor the solar system existed! 

"Light year" in astronomy is a unit of measurement of distance, it is the distance that light travels in space in one year.

I captured this photo on a spring night in Talash village in the highlands of Gilan province in Iran.