Think it’s been hot in the northeast U.S. this week? How do you think you’d like the conditions on the sun? OK, there’s a little bit of an apples-and-oranges quality to the comparison, but even by solar standards, things have been fiery out there of late. Two summers ago, the sun emerged from a four-year period known as a solar minimum, which is as quiescent as it sounds: sunspots, magnetic storms and the massive blasts of charged particles known as coronal mass ejections (CMEs) grow comparatively still and the sun becomes as peaceful as a massive ball of gas measuring 864,000 mi. (1.389 million km) across, with an interior temperature of 27,000º F (15,000º C), can get.
But in August 2010, the sun woke up, beginning the more active part of its 11-year cycle. It announced its stirrings with a massive CME that blasted toward Earth, sparking warnings that it would fry communications satellites and completely unwire the wired world. That’s not a totally unrealistic fear—though that time we were spared any ill effects. Instead, the charged particles in the CME did what they always do, which is to say they swarmed around the planet without ever touching it—thanks to Earth’s magnetic field—and spilled into the atmosphere at the poles, producing the magnificent sky-show known as the aurorae. Not a bad way for an act of such cosmic violence to wind up.
Things weren’t as peaceable on our sister planet Venus. About the same size as Earth, with an atmospheric and surface chemistry that might once have been similar, Venus is a cautionary tale about what happens when the wheels completely come off a new planet. At an orbit of 67 million mi. (108 million km) from the sun, Venus is 26 million mi. (42 million km) closer than Earth. That, by itself, would have made it a toastier place to live. But Venus also has virtually no magnetic field. That means an open door to the charged particles of the CMEs, which sweep away hydrogen and oxygen—and thus water—in the atmosphere, turning the planet into a hot, sulfurous oven. Life? Not a chance. Zinc and lead can’t even survive the 860º F (460º C) heat.
NASA, which knows a thing or two about such matters, has just posted a video that captures all this vividly. It’s worth watching not just to understand what things are like on the woeful world that is Venus, but to appreciate again how good they are here — and why it’s worth looking after what we’ve got.