Using the Schwarzschild radius calculations, what would be the radius of a black hole with the same mass as the Sun?

But contrary to popular myth, a black hole is not a cosmic vacuum cleaner. If our Sun was suddenly replaced with a black hole of the same mass, Earth's orbit around the Sun would be unchanged. Of course, Earth's temperature would change, and there would be no solar wind or solar magnetic storms affecting us. To be "sucked" into a black hole, one has to cross inside the Schwarzschild radius. At this radius, the escape speed is equal to the speed of light, and once light passes through, even it cannot escape.

If the Sun was replaced with a black hole that had the same mass as the Sun, the Schwarzschild radius would be 3 km (compared to the Sun's radius of nearly 700,000 km). Hence the Earth would have to get very close to get sucked into a black hole at the center of our Solar System.