NGC 2239 is an open star cluster located in the constellation of Monoceros, also known as the Unicorn. It was discovered by the astronomer John Herschel in 1834. This cluster is part of the larger Rosette Nebula region and is approximately 4,500 light-years away from Earth. The cluster contains several young, hot stars that are still in the process of forming. NGC 2239 is estimated to be around 2 million years old and spans about 10 light-years across. Its bright stars contribute to the overall beauty of the surrounding nebula, making it a popular target for amateur astronomers.