Possibly the Matthew Looney series by Jerome Beatty Jr.
The Matthew Looney books chronicle the adventures of a brother and sister, Matthew and Maria Looney, who live in the town of Crater Plato, on the Moon. In Beatty's stories, the inhabitants of the Moon are a fully developed non-human civilization. Beatty's fictional Moon inhabitants are an indigenous species, living on the Moon without the assistance of spacesuits, "breathing" vacuum instead of air. A recurring theme in the books is Matthew's desire to know more about outer space, especially the Earth. At the beginning of the series, he looks up in the sky at the Earth and wonders if anyone is living on it.
Similar to most child characters in children's literature, the Looney kids must deal with parents, friends, and rivals, along with the normal array of school-age joys and concerns. Their father works in the "powder factory," but Matthew is captivated by the notion of an exciting career in the military like his uncle, Rear Admiral Looney. Maria, his younger sister, prefers playing sports after school and getting in trouble with her best friend and rival, Hester.
During their adventures, the Looney kids face space pirates, a war between the Moon and Mars, the "discovery" of life on Earth, and the invasion of an Earth circus.
Book 5 featured Matthew's sister, Maria Looney and the Red Planet. There are others in the series, but that is the one I remember. It does have a reddish orangeish cover.