`Sagittarius A*` refers to a supermassive black hole located at the center of our Milky Way Galaxy. Let`s dissect each option for a better understanding:

Option 1 correctly identifies Sagittarius A* as a supermassive black hole in our Milky Way Galaxy. This supermassive black hole is about 4 million times the mass of our Sun and forms the gravitational center of our galaxy.

Option 2 is incorrect. While interesting, it does not describe Sagittarius A*. This option refers to a hypothetical scenario where two black holes are spiralling around each other.

Option 3 is also incorrect. Sagittarius A* is not a supernova explosion. A supernova is a stellar explosion that can momentarily outshine an entire galaxy, but it does not describe this particular black hole.

Option 4 suggests that Sagittarius A* is an asteroid, which is incorrect. Asteroids are small, rocky objects that orbit the sun. They are quite different from black holes, which are regions of spacetime exhibiting such strong gravitational effects that nothing can escape from inside it, not even light.