One thing is clear - all the inhabitants of the Earth will have hard times because of the complete fading of our star.
It's hard to imagine what would have happened to the Earth if the Sun had disappeared even for a day: we are so dependent on the star that life seems impossible without it. In principle, this statement corresponds to the truth: this is the conclusion reached by scientists from all over the world, who gathered in a team to conduct the study. They decided to find out what changes will occur on Earth if the Sun goes out for exactly one day.
They carried out all their observations using a computer model. She showed that in 24 hours absolutely all plants will die and stop producing oxygen, without which the life of humanity and other creatures is a priori impossible. A few hours after the extinction of the Sun, night will come on the planet: it will be enveloped in a dark cover, through which the rays of other stars will break through.
In this case, the moon will remain invisible to us, because it will not be illuminated by the main luminary of the solar system. The temperature of the Earth's surface in 24 hours will drop to +7 degrees Celsius, and in a week it will generally drop to minus.
In principle, the changes will not go unnoticed by anyone except the underwater inhabitants: they both swam in their seas and oceans, and will swim.