The miracle of Dunkirk: 40 facts about the famous evacuation. AS ceremonies to commemorate its 75th anniversary begin JAMES MOORE reveals 40 facts about the famous evacuation. 12:59, Thu, May 21, 2015 | UPDATED: 14:33, Thu, May 21, 2015. GETTY. 338,000 troops were rescued from the beaches of Dunkirk in Operation Dynamo.
Sunspots are magnetic regions on the Sun with magnetic field strengths thousands of times stronger than the Earth's magnetic field. Sunspots usually come in groups with two sets of spots. One set will have positive or north magnetic field while the other set will have negative or south magnetic field. The field is strongest in the darker parts of the sunspots - the umbra. The field is weaker and more horizontal in the lighter part - the penumbra. Click on image for larger version.
Sunspots are darker than the surrounding areas because they are expending less energy and have a lower temperature. Sunspots often have poles (polarity) like the south and north poles of magnets. Sunspots are formed continuously as the Sun's magnetic field actively moves through the Sun.The sunspots have lifetimes of days or perhaps one week or a few weeks. Here is one scenario that some scientists think explains how sunspots form.Imagine the magnetic field on the Sun as loops like rubber bands that wrap around the Sun, with one end attached to the south pole and the other end attached to the north pole.ere is one scenario that some scientists think explains how sunspots form. Imagine the magnetic field on the Sun as loops like rubber bands that wrap around the Sun, with one end attached to the south pole and the other end attached to the north pole.