Researchers Study Explosions on Venus

A new study finds strange, gigantic explosions fueled by solar energy detonate just above the surface of  Venus.

The huge eruptions, known as hot flow anomalies (HFAs), have been seen before near Earth, Saturn and possibly Mars. According to researchers the new observation is the first unambiguous confirmation of the phenomenon on Venus. It also shows that HFAs there are far different than what happens near our planet, which has a strong magnetic field. At Venus, since there’s no protective magnetic field, the explosion happens right above the surface of the planet. HFAs are caused by discontinuities in the solar wind, the million-mph flow of charged particles that streams from the sun. Sometimes these discontinuities, areas where the wind’s magnetic fields change direction sharply and abruptly, align with the wind’s flow. In this case, they remain in contact with the bow shock, the place where the solar wind slows down quickly and diverts around a planet or other large body. If such a discontinuity travels slowly across the bow shock, it traps lots of solar particles, collecting pools of super-hot plasma that can expand to be as big as Earth. These eruptions of hot plasma are dramatic events that can compress Earth’s entire magnetosphere, the protective magnetic bubble surrounding our planet. Such explosions also cause solar particles to flood into Earth’s atmosphere near the poles along the planet’s magnetic field lines, sometimes generating intense displays of the northern and southern lights. The search for this kind of space weather on Venus began in 2009 when NASA’s Messenger satellite, which is actually a mission to study Mercury, spotted what may well have been an HFA at Venus. But Messenger’s instruments could only measure a suggestive magnetic signature, not detect the temperature of the material inside, a necessary measurement to confirm the heat of a “hot” flow anomaly. For further evidence, Collinson turned to a European Space Agency spacecraft called Venus Express. Venus Express was not designed to study space weather phenomena per se, but it does have instruments that can detect magnetic fields and the charged particles, or plasma, that make up the solar wind. The researchers determined that Venus Express flew through an HFA on March 22, 2008, showing conclusively that the phenomenon exists at Venus. But HFAs likely cause explosions much closer to the surface of  Venus than the Earth variety, because Venus lacks a magnetic field. While the researchers think Venusian HFAs probably push part of the planet’s atmosphere out into space, they’d need a dedicated spacecraft to really nail down the phenomenon’s full effects. But the study does suggest that HFAs may well be common on planets throughout our solar system.