As the sun is getting closer to the peak of activity in its 11-year weather cycle, things are becoming interesting. Astronomers observed a massive solar flare erupt on the sun yesterday and it's only the beginning.
The flare spewed off huge amounts of superheated plasma into space, heading our way in fact. The flare wasn't big enough to cause any big problems on Earth, but future ones might be.
The flare originated in the gigantic AR1654 sunspot (active region), much larger than the Earth. The sunspot is full of M (medium) class flares, one of which erupted yesterday.
If it hits Earth, the material flung off by an M-class flare can cause some problems at the poles, but that's about it, the Earth's magnetic field is enough to shield us.
If it were an X-class flare, the largest kind, it could have caused some serious damage on Earth, such as damaging communications and power lines.
AR1654 is slowly turning towards Earth so any explosive flare could directly affect us. The sun's activity peaks this year so you can expect plenty of events like this.