Asked by Sasha Fox
For one thing, our system would be much colder. On Earth we live in what is called the goldilocks zone, a distance from our Sun that is just right for liquid water to exist. The goldilocks zone around a red dwarf is much closer and here on Earth we would likely freeze. Trying to live around this new red dwarf star would also mean that we had more intense magnetic fields and violent solar flares to deal with.
Red dwarfs stars are smaller and cooler than our relatively average star, the Sun. They are also the most common star type in the universe. We think that many red dwarf star systems may have habitable, Earth-like planets that orbit them but replacing our Sun with a red dwarf would be rather disruptive to our Solar System and home planet.