The sun is midway through its life of fusion. It’s about 5 billion years old, and though its life is far from over, it will undergo some pronounced changes as it ages. Over the next billion years, the sun will continue to brighten. The sun is midway through its life of fusion. It’s about 5 billion years old, and though its life is far from over, it will undergo some pronounced changes as it ages. Over the next billion years, the sun will continue to brighten. Astrobiology Planetary Sciences Phys.org – latest science and technology news stories