…And Eternity in an Hour
Alrakis was the home planet of the Tonska until they were destroyed by a mobile temporal rift.
Alrakis orbited the star Iota Ophiuchi and from space looked violet, due to its atmosphere. It had single large moon, which was mined extensively by the Tonska and which had a decaying orbit. It crashed into Alrakis thousands of years after the Tonska had vanished. (…And Eternity in an Hour)