Answer:
Space carries a massive atmosphere that can be adverse for planets. For example, stars tend to flow gases knows as stellar winds, high-intensity rays known as the cosmic rays flow through space, solar winds from the sun are also very harmful.
For a planet to be habitable, the magnetic field is essential to deflect the solar winds and other harmful rays. Without the magnetic field, the planet would emit harmful rays from the Sun making and hence, no life would be able to sustain on it.
