The accidental scientist

Last week I checked our spare water bottles. I was a bit disappointed because one of them was green. Full of green algae indeed. What a nuisance! But on second thought, I reflected that without the ancestors of these green algae, you and I wouldn ’ t be here to whinge about them. Let ’ s go back 2.7 billion years. The Earth is well and truly uninhabitable. The atmosphere is full of carbon dioxide, methane, ammoniac, a bit of nitrogen thank to volcanic eruptions, water vapour and no oxygen. The sun is 20% weaker than today but with the greenhouse effect, it ’ s still a tad less than 40 degrees out there. Cyanobacteria appear somewhere in the shallow ocean and kick start the Great Oxidation Event, doing the fantastic job plants still do today: photosynthesis. Cyanobacteria are blue-green algae. They use visible light, water and carbon dioxide to make carbohydrates and oxygen. The more efficient green algae appear only 2 billion years later, followed by land plants another half billio

  0n 29 September 2020 the BOM declared a La Ni ň a event, which means wetter than average conditions in the next few months. How does that work? It all depends on the Walker circulation. Gilbert Walker was a Cambridge University mathematician who became director general of observatories in India in 1904. He studied the Indian Ocean monsoon. What he found is that the temperature differences between land and sea powers the monsoon. We all know about the afternoon sea breeze. The air over land heats up and rises, this causes the air above the sea to come in and replace it. At high altitude, the air moves back from land to sea. This forms a loop which is indeed a mini Walker circulation. Extend the idea to the Pacific tropical zone. The ocean surface is warm somewhere North of New Guinea, and cold in the East near the America coast. So you get the trade winds blowing from East to West at low altitude, and the other way around further up. This is the Walker Circulation. So over PNG and

I had once the privilege to spend a year on an Antarctic station. I used to sit all night in a heated polycarbonate dome to look at auroras. I spent many hours marvelling at the best night sky on this planet. No light pollution, no smoke, no clouds, it was just perfect. Well, I now live near Casino, far enough off town not to be disturbed by streetlights. No auroras here but the sky is almost as good! I love looking at the planets. At the moment you can look at Mercury above the Sun between sunset and 8:20 pm. But Mars is the star of the show! Being opposite the Sun, Mars is at its shortest distance from us, in full phase and visible from sunset to sunrise. If you look at your East sky around 9-10pm, you can ’ t miss this big red spot, the brightest thing visible. If you look North and high, Jupiter and Saturn are easily visible: right on the ecliptic, of course, about half-way between Mars and where you guess the Sun is. You can even have a glimpse at Uranus! Until 2 weeks ago I t