How many moons does Mars have?
Mars has two moons, they were named Phobos and Deimos by the American astronomer Asaph Hall, who discovered them in August 1877.
Instruction: How many moons does Mars have?
Context: 
Response: Mars has two moons, they were named Phobos and Deimos by the American astronomer Asaph Hall, who discovered them in August 1877.