No, the aurora borealis is not caused by aliens. It is caused by the sun. The sun gives off high-energy charged particles called ions. These ions travel into space at the speed of 300 to 1200 kilometers per second. When the ion particles are shot off from the sun it is called plasma and plasma becomes solar wind. This solar wind interacts with the magnetic field of the earth. Some of the particles are trapped by the magnetic field in our ionosphere (earth's atmosphere that is about 60 to 600 kilometers above the surface of the earth). There are gases in the ionosphere and when these particles from the sun collide with the gases it creates a light show - the aurora borealis. There are auroras at both the northern and southern portion of the earth. 

The auroras are constantly in motion because of the interaction of the solar wind and the earth's magnetic field (which is consistently changing). Solar wind generates up to 1,000,000 megawatts of electricity in the aurora displays. Scientists study the auroras to determine if there is a way to utilizing the energy generates by the interaction of the solar wind with the magnetic fields of earth.