The Good News:
* Gravity Remains the Same: The gravitational force of a black hole is determined by its mass. Since the black hole would have the same mass as the Sun, the gravitational pull on the planets would remain identical. This means the planets would continue to orbit the black hole as they currently orbit the Sun.
* No Immediate Heating or Cooling: The Sun's energy comes from nuclear fusion, not its gravity. A black hole doesn't produce light or heat, so the planets wouldn't experience any immediate drastic changes in temperature.
The Bad News:
* Darkness: The most obvious change would be the utter darkness. Without the Sun's light, the planets would plunge into eternal night. This would have a devastating impact on life, as photosynthesis would cease and temperatures would plummet over time.
* No Solar Wind: The Sun emits a constant stream of charged particles called the solar wind. This wind protects Earth from harmful cosmic radiation. A black hole wouldn't emit a solar wind, leaving us vulnerable to damaging radiation.
* Long-Term Orbital Instability: While the initial gravitational pull remains the same, the lack of the Sun's light pressure would cause subtle changes in the planets' orbits over time. This could lead to instability and even collisions between planets in the distant future.
The Ultimate Fate:
* Frozen and Dark: Without the Sun's energy, Earth and the other planets would eventually freeze solid. The lack of light would lead to the extinction of all life.
* Tidal Forces: While the gravitational pull remains the same, the closer a planet gets to a black hole, the stronger the tidal forces become. Over long periods, these forces could tear planets apart.
In Conclusion:
Replacing the Sun with a black hole of the same mass would be a catastrophic event for life on Earth. While the immediate impact might not be as drastic as one might imagine, the lack of light, warmth, and the solar wind would ultimately lead to a frozen, lifeless solar system.
