Earth's magnetic field shields us from most of the worst effects of the solar wind. But our bizarro twin Venus has no such field, meaning its atmosphere is the only defense against the solar wind. That's where things get interesting.
The Sun shoots off solar wind at about a million miles an hour, and it usually gets to just under 50,000 miles from Earth before it hits the magnetosphere. Most of the wind flows around this magnetic shield, meaning we're protected from most - though certainly not all - of the solar wind and its potential hazards. But on Venus, the solar wind routinely reaches its atmosphere, which is where NASA scientist David Sibeck and his team have observed some seriously bizarre space weather effects.
When the solar wind hits something - that something being, in most cases, a planet's magnetic field - it can sometimes create a phenomenon known as a hot flow anomaly. In these, the solar wind temporarily reverses direction, with material shooting backwards. This sudden rush of material creates an explosion. We've seen such anomalies around Earth's magnetic fields, as well as around Saturn and possibly Mars as well.
The question Sibeck and his fellow researchers set out to answer was whether these hot flow anomalies also occur on Venus, which unlike those other planets has no magnetic field. Since the fierce conditions on Venus make direct observation extremely difficult, he relied on an indirect technique: the ESA's Venus Express mission that is currently in orbit around the planet.
Although this satellite can't actually measure space weather, some of its instruments would have a telltale magnetic response to a hot flow anomaly that happened in its vicinity. After combing through three years of data, Sibeck discovered just such an explosion occurred on Venus on March 22, 2008. Exactly what these hot flow anomalies look like on Venus is an open question, and we won't know for sure until we can figure out how to directly observe one, a task complicated by Venus's intense conditions.
But, as you can see illustrated in the video up top, these hot flow anomalies most likely occur right near the surface of the planet. Without a magnetic field to keep the explosions far away from the planet, Venus likely experiences the full brunt of these plasma shockwaves. The only good news for Venus is that without a magnetic field to excite the plasma in the solar wind, the explosions are likely a bit more mild than those that occur near Earth. Of course, that hardly makes up for the fact that pretty much the entire Venusian atmosphere can explode at seemingly any moment. And just when I thought Venus couldn't possibly get any worse...
For more, check out NASA. Video by ESA/C. Carreau.