Viswanathan K's Thoughts

When a (big enough) meteor hit the earth the last time around, the dinosaurs were its most famous casualty. But that’s not why NASA setup CNEOS to keep an eye for asteroids! Instead, it’s due to something humans saw happen, write Jorge Cham and Daniel Whitman in Frequently Asked Questions about the Universe : “In 1994, the comet Shoemaker-Levy 9 broke into twenty-one pieces on its way toward the sun, and those frag­ments crashed into Jupiter. One of those pieces created a gigantic explosion approximately the size of Earth.” Yes, an explosion as big as the earth.   As of today: “The CNEOS team has created a pretty good database of all the biggest rocks around us, where they are, and where they will be in the near and far future.” The good news is that the biggest rocks are rare (That’s good news since it’s the biggest ones that can cause catastrophic destruction). Even better: “Luckily, large rocks like that are not only rare but also relatively visible. If a large ro...

Have you heard of any natural nuclear reactors, other than stars? In Oxygen , Nick Lane talks about the one in Gabon (Africa), and how that came to be. But first, remember how fission bomb works? Uranium’s isotope, U-235 decays and emits a few neutrons. Slow down those neutrons using hard water, and you’ve increased the odds of those neutrons hitting the next U-235 atom. The process starts to repeat itself. If this process can continue long enough, you have a nuclear explosion. The key, of course, is to get enough concentration of that U-235 in the first place. So how did all this happen naturally on earth?   The solubility of uranium in water depends on the oxygen level. As the oxygen level started rising about 2 billion years back, “oxidized uranium salts leached out of uraninite ores in the rocks and washed away in streams”. Of course, it was very dilute, fewer than a few parts per million.   Many such streams converged in Gabon’s shallow lakes. As it turned out, t...

A lake in Turkey went biblical: it turned blood red. But fear not, says Danny Gallagher , it happens every summer! “The apocalypse isn't coming to fruition…(Toz Golu lake) turns bright red due to an interesting anomaly that occurs every summer.” (In case you’re curious, it happens because as the lake dries up in summers, the salt level increases; the rising salt level kills off the plankton that eat the algae; and the uncontrolled algae have this color changing ability). Nature red in tooth and claw, said Lord Tennyson. Just how red it can be was exemplified by a recent discovery of how the boa constrictor (a snake) kills its prey. It was thought that they squeeze the life out of their prey (literally), i.e., they squeeze and squeeze until the prey suffocates. Turns out the modus operandi is even more lethal : “Death by suffocation is nightmarish enough, but boa constrictors do something even more sinister: They cut off your blood supply…Many animals (humans included) ...

Heard of the Goldilocks Zone? It was a term defined nearly 2 decades back to refer to a belt around a star that scientists felt would be right for life to exist. Any closer and things would be too hot; any farther and it would be too cold. Hence the name of the belt after the fussy girl from the fairy tale. Well, since then satellites and telescopes have collected a lot more data about the atmosphere of other planets. And since the atmosphere affects how much heat a planet absorbed (if you hadn’t slept through most of your schooling days, you’d have known that), it follows that all the new data should trigger a revision of the Goldilocks Zone limits. So a team of astronomers did just that. Based on the data, they pushed back the Goldilocks belt further back from the respective star. That move obviously means some of the planets earlier considered good candidates for life would now be too close to the fire and need to be dropped from the prospective candidates list. Now c...