NASA has released a free e-book titled Hubble Focus: The Dark Universe. You can download the book at the NASA site in one of two formats – PDF or EPUB. This is the fifth edition of this book.
You cannot argue with the price, while the content is an impressive story about how the Hubble Space Telescope has helped to study both dark matter and dark energy. In addition to the text and images, the book contains links to numerous videos that further illustrate the points in the book. It is a multimedia experience that can only enhance your understanding of the topic.
Hubble is just the beginning, as the James Webb Space Telescope and other instruments are coming online to assist with the research. The book notes:
Hubble continues to be a vital tool to address questions about the underlying workings of the universe . Scientists will pair its wide wavelength coverage with James Webb Space Telescope’s powerful vision, the upcoming Nancy Grace Roman Space Telescope’s panoramic view, and a fleet of additional space- and ground-based telescopes to explore the cosmos as never before . We have far more left to learn among the stars
Our Awesome Universe 