Sh2-138 and Sh2-139 are emission nebulae located in the constellation Cepheus. They are part of the Sharpless catalogue, compiled by Stewart Sharpless and published in 1959. It is a busy area when it comes to Sharpless objects, with the well known Wizard Nebula (Sh2-142) nearby. There is a lot of controversy about the distance of these two objects, with estimates ranging from around 2,500 light-years up to 10,000 light-years.