Expressly Venus

Artist concept of lightning on Venus. Credit: NASAVenus has reentered our sky in its part-time job as the Evening Star, appearing as a uniquely brilliant white beacon over the western horizon after sunset.

With all the attention that the exploration of certain other planets has received lately, I feel that Venus exploration has fallen off our radar a bit, and that it is high time for an update.

There is no lack of exploration of Venus today: NASA's MESSENGER spacecraft, bound for Mercury, flew by Venus twice (2006, 2007), making observations on the fly; Japan is currently planning to send a climate orbiter mission ("Planet C") there in 2010; and the European BepiColombo will perform a couple of Venus flybys of its own, in 2013, on its way to Mercury.

Most notably, the European Venus Express orbiter is in the middle of a two-year mission of exploration, and has revealed new and fascinating things about Venus--a planet whose cloud-shrouded surface kept us mostly ignorant about it until recent decades. (Before the 1960's it was even speculated that Venus might be a steamy swamp or rain forest world!)

Here's a quick recap of some of the highlights of Venus Express's findings:

"Hurricanes" at the poles: Venus Express's VIRTIS instrument, which is able to probe several different layers of the atmosphere, has put together a detailed picture of wind behavior at different latitudes and different altitudes. What was discovered from these observations is that Venus has giant, hurricane-like vortexes capping its poles. Winds within these systems all flow in generally the same direction, as you'd expect with hurricanes, circling mostly windless "eyes" at their centers at the poles.

Lighting: Evidence of lightning on Venus was detected by earlier orbiter and lander missions, and Venus Express has confirmed it--maybe more lightning activity than on Earth. What makes Venus's lightning unique among the planets with lightning (Earth, Jupiter, and Saturn, as far as we know) is that it's the only case where lightning is formed by something other than clouds of water droplets--in Venus's case, sulfuric acid droplets do the trick. Lightning can be an important factor in that it breaks up atmospheric molecules and allows them to recombine in different forms.

Active volcano search: It has long been suggested that there may be active volcanoes on Venus today, though no direct evidence (like images of erupting volcanoes, for example) have yet been obtained. Venus Express has measured large variations over time in the concentrations of sulfur dioxide in Venus's atmosphere--a compound that on Earth comes from volcanic eruptions.

There's a lot more to say about Venus, as it is a world as varied and fascinating as the Earth (minus the life forms, as far as we know). Though it may not be the hottest vacation spot in the solar system, with its pressure cooker of a toxic, acid-laced atmosphere, it is one of those great mysteries that we actually get to watch unfold before us as exploration of it moves forward.

37.8148 -122.178