... 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. ...
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. ...
... The craters were caused by the impacts of comets and asteroids. ... In fact, up to a diameter of about 10 meters (33 feet), most stony meteoroids are destroyed in the atmosphere in a terminal explosion. ... The famous meteor crater in northern Arizona, some 1.2 kilometers (4,000 feet) in diameter and 183 meters (600 feet) deep, was created 50,000 years ago by a nickel-iron meteorite perhaps 60 meters (197 feet) in diameter. ... These range in diameter from a few meters to about 8 km. ...