Well Mythology is super vast, but I always think a good starting point can be the very source texts themselves. The Iliad and Odyssey are both accessible books that tell a great story. Likewise the Metamorphoses by Ovid is a good read (Although this uses the Roman names as Ovid was Roman).
If you'd rather a collection of stories or an author talking presenting different variations of the stories, I think it depends what stylistic approach you want. For example, Edith Hamiltons Mythology book is often recommended, or Robert Graves as well. I mean, what sort of style of book where you looking for?
Here I found an interesting Article which tells about some of the most wonderful and fascinating legends about the sun from cultures around the world.
1. Aztecs (Mexico)
2. Ancient China (China)
3. Ancient Egypt (Egypt)
4. Ancient Greece (Greece)
5. Inuit (Greenland)
6. Maori (New Zealand)
The ancient Greeks believed that the sun travelled across the sky in a flying chariot ridden by Zeus’s son, Apollo, and driven by fiery horses. Apollo was important in Greek culture not only because he represented the sun, but also because he was seen to illuminate the worlds of music and reason. He brought logic and order to humanity and provided everyone with the light and warmth of the sun.