It’s not easy being human: some things are just too impressive to appreciate. Take the storm that is raging on Saturn, for example. It covers an area the size of the earth. How do you begin to wrap your imagination around that?
Then there’s the fact we have finally worked out what creates such a monster, and why these storms arise only every few decades. For this, a phenomenon that occurs more than a billion kilometres away, we now know a truly impressive amount. A paper published this month in the journal Nature explains the detail for the first time. All the data we have gathered tells us that Saturn’s storms – also known as its Great White Spots – are uncannily like terrestrial thunderstorms. They arise from a scaled-up and twisted version of our own water cycle, complete with spectacular lightning discharges.
The difference between earth’s and Saturn’s storms lies mainly in the composition of the atmosphere. Saturn is coated in a layer of hydrogen and helium, the two lightest gases. Water vapour is much heavier. Consequently, the process of heating and convection that drives an almost daily cycle of cloud build-up and discharge on earth takes about 20 years on Saturn.
Water is also involved in another impressive new discovery – this time on Mars. In March, observers using Hawaii’s Keck and Infrared telescopes revealed that the atmosphere of Mars still holds traces of a huge lost ocean. The 20 million cubic kilometres of water would have been roughly a mile deep in places and covered a fifth of the Red Planet’s surface. Though dry and dusty now, Mars might once have been extremely hospitable to life.
What’s more, there may be enough water left on or under the planet’s surface to keep some life forms going. Nasa’s Curiosity rover has been measuring how temperature and humidity rise and fall there through the day and night. Its measurements suggest that water condenses out of the thin atmosphere at night, but instead of freezing in the sub-zero temperatures it remains liquid, pooling on the planet’s surface.
This is due to the same phenomenon that stops terrestrial water freezing when we grit the roads. Martian soil contains salts called perchlorates, which lower the freezing point of water so no ice can form. The first five centimetres or so of Martian soil are probably wet at night, before drying out through evaporation in the day. Given the intense cold of Martian night (-30°C is the average temperature), none of earth’s organisms could remain alive on the Red Planet. But there is a small possibility that more hardy forms of life have remained viable on Mars.
These kinds of insights are, in many ways, ten a penny these days. All around the globe we operate hundreds of telescopes and dozens of spacecraft, and pay many thousands of scientists to tell us about the composition of the solar system and beyond. Clearly we crave this kind of knowledge. But we don’t really put it to work. We write it up in scientific journals, in newspapers and magazines, broadcast footage from alien worlds, or show humanity we can land a robot on a comet. Then we go back to arguing about whether it is OK to indulge our antipathy towards certain groups of human beings, or whether leadership qualifications should include the ability to eat a bacon sandwich with decorum.
Our brains are agile enough to create technology that gathers knowledge about vast alien storms, about ecosystems that have dried into wind-blown dust and about threats we are creating to peaceful human habitation of earth. No one would deny its value – but what do we do with it? We have yet to work that out.
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