The night sky acts like a "time machine", because light moves at a limited speed in the universe and it does not reach us instantaneously from any distant point. In fact, by staring at the stars and galaxies, we are watching 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 in one of the villages of "Tenkabon" city in the north of Iran after about 1 day of walking and hard climbing on a summer night at an altitude of 3800 meters. In the background, you can see the famous Siah Kaman mountain range and Alam Kouh peak. JPEG image Edition: 1/1 Size 2000 * 2600 px