What would happen if our planet got too close to a black hole? According to science fiction, we’d be sucked into a parallel universe, or maybe even the future. But in reality, it wouldn’t be nearly that fun.
Instead, our planet would be ripped apart, piece by piece, starting with our atmosphere. So what if we moved a little further back? Instead of the black hole being right beside us, we move it to the center of our Solar System.
Would our planet still be destroyed? And what would that do to our Solar System as a whole?
This black hole has the same mass as our Sun. If we were to place it next to our Sun, the two objects would orbit each other at a close distance, about 1/10 the distance between Earth and the Sun.
This would mean that our Solar System was now orbiting a local point with twice the mass of the Sun. As a result, the planets would have to orbit faster to avoid getting pulled inwards.
A year on Earth would decrease from 365 days to 258 days, and the amount of energy from the Sun would vary as it orbited closer to and farther away from Earth. Other than that, life would be pretty well the same.
But what if we replaced our Sun with a black hole completely? Well, we’d have a lot more to worry about than just the length of a year. Which, by the way, would be over in the blink of an eye.
The biggest problem we would face if we replaced the Sun with a black hole would be the absence of incoming solar energy. The planet Earth would go completely dark. Thanks to our planet’s infamous greenhouse gas effect, the global temperature would not be reduced instantaneously.
But after the first week, Earth’s average surface temperature would drop to 0°C (32°F), and then to negative 101°C (-150 °F) by the end of the first year. You’d think that our planet quickly becoming an ice world would be bad enough, but we’re just getting started.
Without sunlight, there would be no photosynthesis, the process by which all plants generate food. Small plants would die within a matter of days. This would create a ripple effect throughout the entire food chain, causing us all to starve to death eventually.
But maybe there is a way we could get usable energy from a black hole. And it all starts with something called CMB. CMB, also known as cosmic microwave background, is the weak radiation left over from the big bang.
Theoretically, if a black hole spins fast enough, it can compress the CMB radiation into optical wavelengths, the same wavelengths that are emitted by the Sun. The wavelengths would funnel into a narrow beam, and before you know it, our planet would have usable energy once again! But there is a small catch.
The faster rotation of the black hole would also pull the planetary orbits in closer to the point of no escape. For the planetary orbits to remain stable and avoid being sucked up, the orbital velocity of the planets would need to be close to the speed of light.
This means that a year on Earth would be over before the blink of an eye. So much for your big New Year’s Eve party. But there’s no time to worry about that because we’ve got bigger issues coming our way.
If any material, like meteors, satellites, or space debris, gets sucked into the black hole, it will result in a blast of radiation coming our way. And when the radiation arrives at our planet, it will blow away our atmosphere, killing anything in its path. So even though the Sun can be annoying sometimes, when it comes to things to orbit around, we could do a lot worse.
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