The power of the sun is reflected in the appereance of a Sun god (or gods) in virtually every mythology and religion. Here are some of the most notable.
Amaterasu
The Japanese Sun Goddess whose full name, Amaterasu Omikami, means “Great Divinity Illuminating Heaven”. The Japanese imperial family claims direct lineage from her, and her emblem, the rising Sun, appears on the national flag. In her most famous story, Amaterasu hid in a cave after a family quarrel, thus plunging the world into darkness. She only reappeared after catching a glimpse of her own magnificence in a mirror.
Helios
The Greek Sun god who in Roman mythology is called Sol and is identified with Apollo. Helios’ task was to drive his horse-drawn chariot across the sky each day. When he allowed his son Phaeton to have a go, the young man was unable to control the horses and came so close to Earth that he burned parts of it. To save the day, Zeus struck him with a thunderbolt and Phaeton tumbled into the river Eridanus.
Huitzilopochtli
The principal Aztec god is both the Sun god and the god of war. His name means “Blue hummingbird on the left”, and he is usually depicted either as a hummingbird or as an armed blue man with a headdress of feathers. The Aztecs believed that Huitzilopochtli needed to be fed human hearts on a daily basis, and would tear out the hearts of captures warriors or slaves.
Lugh
This Celtic Sun god, whose name means “brilliant one”, was skilled in all the arts and crafts. In the Irish version of his myth, he killed his evil grandfather Balor (who tried to have him drowned) by throwing a magic stone at his eye in battle. Lugh became the leader of the Tuathu De Danaan (descendants of the goddess Danu). His festival Lughnasadh, celebrates the beginning of the harvest.
Ra
Also known as Re-Horakhty, this Egyptian Sun god was believed to traverse the sky in a boat by day, before being swallowed by the goddess Nut to be reborn each morning as a scarab beetle. His symbol was the winged Sun disc, but he was also depicted in human form with a falcon head. Ra was associated with the pharaohs who saw themselves as his sons. He was also believed to have been the creator of the world, first creating himself and then the other gods.
Quoted from page 38 of the book The Rough Guide to The Universe (Rough Guide Science/Phenomena) by John Scalzi
Above explanations are reflecting the scientific point of view. Obviously, the Sun effects our lives directly. Without the Sun, no life will be formed on Earth. We need the radiating energy of the Sun. We need the Sun “ra“ys. I agree that the primitive human mind has to cook up the Sun god stories, and later theories. Why we have the darkness at nights? Why the world is colder at winter? What if the Sun never come back and the Sun sentenced us to scary darkness or cold winters? These kind of questions have to be answered. Especially for the people of the ancient days who deprived the wonders of the electricity or even candle lights. At that times, humans lived in the total darkness at nights. It’s frightening, isn’t it? So, you need answers.
At the other hand, there’re some anomalies. Earth is a big planet when you compare it to little human body mass. How did all the ancient cultures create similar stories or myths? I know, the Sun is everywhere 
Pass beyond it and concentrate on details…
The Rough Guide to The Universe (Rough Guide Science/Phenomena)