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Raymond T. Pierrehumbert’s Followers (2)
Raymond T. Pierrehumbert
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“Regardless of our destiny, the clear miracle is that little blobs of protoplasm making up a species barely a hundred thousand years old living in the outskirts of a not especially remarkable galaxy have been able to learn so much about the Universe around us. We have peered back to the moments after the Big Bang, and have inferred the likely fate awaiting trillions of years from now. We have been able to probe the farthest reaches of the Universe by detecting the feeble vibrations of gravitational radiation, and have begun to lift the veil on what planets are out there, and what they may be like. The saga of exploring planetary systems has just begun. There is no limit to what we can accomplish, if we can make it through the next few hundred years without crashing the Earth’s habitability, and without letting the authoritarianism emerging throughout the world crush the human spirit, dividing us one from the other, and separating us from our better natures.”
― Planetary Systems: A Very Short Introduction
― Planetary Systems: A Very Short Introduction
“Until relatively recently, there was no real need for a term referring in general to the kind of object our Solar System is. It was the only known object of its type. We knew of stars but no planets outside the Solar System. We had no ability to observe planet formation in action. That has all changed, but so recently that there is no generally agreed term in the astronomical community for a star and all the gravitationally bound objects surrounding it. The term ‘planetary system’ has begun to gain currency to describe such objects, and it is the term we adopt to refer to a star and all the bodies gravitationally bound to it—the planets whether rocky, gassy, or icy, their moons, the asteroids, comets, and the far-flung icy bodies that make up Kuiper Belts. Our own planetary system contains only one star, but other planetary systems commonly contain two or even three stars. While the same general processes that formed our Solar System were also operating in the formation of other planetary systems, the end result of the process can yield planetary systems very unlike our own. Now that the Solar System isn’t the only example of a planetary system subject to study, and now that we can in effect peer back in time and observe processes such as those that occurred billions of years ago when our Solar System was being born, we can begin to appreciate how our home planetary system, and indeed our home world, is or isn’t special. The veil has been lifted, and this book provides a glimpse of what has been revealed.”
― Planetary Systems: A Very Short Introduction
― Planetary Systems: A Very Short Introduction
“How many habitable planets are there?
From Figure 12 it is evident that there are a handful of planets with instellation in the habitable zone range, and which are also of a size or mass small enough to have a potentially rocky composition. Most of these orbit M stars, but that is just because smallish planets with Earthlike instellation are easier to detect around low mass stars. Taking into account the effect of stellar type on the habitable zone instellation boundaries, at the time of writing there are eighteen known planets in the habitable zone, including Proxima Centauri b (orbiting our nearest stellar neighbour) and planets d, e, f, and g in the remarkable Trappist 1 system. There are an additional twenty-six near-misses which could perhaps be rendered habitable if cloud conditions or other uncertain bits of climate physics become more favourable than current best estimates. One would like to extrapolate from this number to an estimate of the proportion of all stars that have a planet in their habitable zone.”
― Planetary Systems: A Very Short Introduction
From Figure 12 it is evident that there are a handful of planets with instellation in the habitable zone range, and which are also of a size or mass small enough to have a potentially rocky composition. Most of these orbit M stars, but that is just because smallish planets with Earthlike instellation are easier to detect around low mass stars. Taking into account the effect of stellar type on the habitable zone instellation boundaries, at the time of writing there are eighteen known planets in the habitable zone, including Proxima Centauri b (orbiting our nearest stellar neighbour) and planets d, e, f, and g in the remarkable Trappist 1 system. There are an additional twenty-six near-misses which could perhaps be rendered habitable if cloud conditions or other uncertain bits of climate physics become more favourable than current best estimates. One would like to extrapolate from this number to an estimate of the proportion of all stars that have a planet in their habitable zone.”
― Planetary Systems: A Very Short Introduction
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