A black hole is a spherical region of space that is so incredibly dense that not even light can escape from its surface, hence the name. The gravitational force of a black hole is extremely strong because all of its matter is concentrated in a core at its center.
GRS 1915+105 lies in our galaxy, the Milky Way, approximately 35,000 light-years from Earth. Gas from a nearby orbital star gets pulled off by the immense gravitational field and spirals onto the black hole, forming a disc of gas around it. This black hole spins at close to the maximum theoretical speed. According to measurements, it can have a maximum spin rate of 1,150 times per second and a minimum rate of 950.