Earth has a magnetic field and Venus does not -- a crucial distinction when assessing the effects of the sun on each planet. As the solar wind rushes outward from the sun at nearly a million miles per hour, it is stopped about 44,000 miles away from Earth when it collides with the giant magnetic envelope that surrounds the planet called the magnetosphere. Most of the solar wind flows around the magnetosphere, but in certain circumstances it can enter the magnetosphere to create a variety of dynamic space weather effects on Earth. Venus has no such protective shield, but it...