What happens when a solar flare hits earth?

The last answer 'the earth is goin to explode because dats something coming from the sun fast' is absolutely rubbish! The solar flare is harmless to Earth because Earth has its own magnetic field so that the solar flare will do very little harm to Earth. After all, the Earth didn't explode on 24/1/2012, when the flare pass earth. The solar flare passing Earth's atmosphere at the two poles (where the magnetic field is close to ground) at high speed creates polar light. It also cause some disturbance to electrical transmission through space and aviation. Astronauts out of Earth's magnetic field, however, have to take measures to prevent direct exposure to the flare.

But even there isn't a magnetic field for Earth, like Mars, matter will only evaporate into space, the planet will not explode.