... The Sun gives us light and heat, sustaining life on Earth. ... This uneven rotation, coupled with the churning of the upper layers, might well be what produces (by a "dynamo mechanism", described in a later section) regions of intense magnetic field, seen by observers on Earth as dark sunspots. ... Near sunspots those streamers seem to be shaped by the Sun's magnetic field lines, and above the Sun's poles they suggest field lines rising from twin magnetic poles like those of the Earth. ...