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Thrilling Discovery of Seven Earth-Sized Planets Orbiting Nearby Star (theguardian.com)
At a press conference on Wednesday, NASA scientists announced that they have spotted seven Earth-sized planets orbiting closely around a small, ultra-cool star. The star is 39 light years away. From a report on The Guardian: It is the first time that so many Earth-sized planets have been found in orbit around the same star, an unexpected haul that suggests the Milky Way may be teeming with worlds that, in size and firmness underfoot at least, resemble our own rocky home. The planets closely circle a dwarf star named Trappist-1, which at 39 light years away makes the system a prime candidate to search for signs of life. Only marginally larger than Jupiter, the star shines with a feeble light about 2,000 times fainter than our sun. "The star is so small and cold that the seven planets are temperate, which means that they could have some liquid water and maybe life, by extension, on the surface," said Michael Gillon, an astrophysicist at the University of Liege in Belgium. [...] While the planets have Earth-like dimensions, their sizes ranging from 25 percent smaller to 10 percent larger, they could not be more different in other features. Most striking is how compact the planet's orbits are. Mercury, the innermost planet in the solar system, is six times farther from the sun than the outermost seventh planet is from Trappist-1.
These were found using the transit method, which measures a star's reduction in it's brightness as something passes in front of it.
They know that these sorts of occurrences are not things like sunspots because they can follow up using measurements of the wobbling of the star due to the gravity the planets exert on it.
Combine the two and you have a reasonable inference that there are planets orbiting this star.
If these are not planets, given the above two types of evidence correlating with each other, what else could they be?
It's a sad commentary about the state of affairs on this world that access to the original article, based on research on paid for with public money, is no free. It's truly appalling.
You're missing a rather important detail there that makes your claim essentially meaningless: time.
We've already launched a few probes that, had we chosen to aim them correctly, would eventually have reached a nearby star system. Sure, Voyager 1 would take ~17,900 years to cross the 4.2ly to Proxima Centauri, but it would so with paltry energy consumption and far less efficient propulsion systems.
Granted, that's probably too slow to interest anyone in making the trip, and the energy requirements increase dramatically as you travel faster, but that's why most near-term plausible speculation assumes (non-FTL) travel between stars would be in generation ships - it's a much easier problem to solve if you're willing to take a century or three to make the trip.
Of course that's a long time to keep a relatively small closed ecosystem healthy, so we'd probably want to wait until we had a century or two of experience building and maintaining long-term viable space stations before we even attempted it.
Also, you talk about the "total generation capacity of the world's electrical grid" as though it's some sort of meaningful indicator about future energy producing capability. In fact though, that's not even a tiny fraction of the energy we're already adding to the Earth today - the CO2 released into the atmosphere by burning fossil fuels captures about a million times more energy than was generated by the power plant.
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Where are you getting "a few percent" from?
There's only 400ppm total CO2 in the atmosphere, that 100ppm represents fully 25% of the total.
Perhaps you're thinking of the fact that CO2 is only a few percent of the total atmosphere? But that's largely irrelevant because almost all atmospheric gasses are completely transparent to thermal infrared radiation, and so don't provide any insulation at all. If they were the only things in the atmosphere the Earth would be as cold as the moon (colder actually, the moon is actually coal black and thus a good thermal absorber)
Water vapor, CO2, and methane are responsible for the overwhelming majority of Earth's atmospheric insulation. Water makes up about 0.4% of the atmosphere (mostly at low altitude), CO2 is about 0.04% of the atmosphere,and methane 0.0002%.
Water is obviously the biggest contributor, but it can't build up in the atmosphere since it rains out as the concentration builds, so it remains fairly constant at a given temperature. It's worth nothing though that it acts as a positive feedback system - the warmer the planet, the more water vapor builds up in the atmosphere, and the more heat will be trapped. So it will tend to make any global temperature changes more extreme.
Methane is actually a considerably more powerful greenhouse gas than CO2 per pound, but there's so little of it that it still only traps a fraction as much heat as CO2. It's also worth mentioning though that humans are estimated to be responsible for somewhere around 2/3 of global methane emissions - we're working hard on that front as well.
Which leaves CO2 as a sort of "thermostat" - more CO2 leads to a warmer planet and faster plant growth, which pulls CO2 out of the atmosphere leading to a cooler planet and slower plant growth, which lets CO2 build up in the atmosphere again... it's a self-stabilizing system that oscillates around some "average" point until something disrupts it - such as dumping carbon into the atmosphere that's been locked underground for millions of years.
As for what difference a few percent can make? Lets do some rough math. Say CO2 is responsible for about 10% of the total greenhouse gas "insulation" (I have no idea, but it makes up about 10% of the total greenhouse gases in the atmosphere so that seems like a good guess). The 100ppm increase would therefore be responsible for about 2.5%. That means the Earth will have to warm up enough to radiate 2.5% more heat in order to shed the same amount of energy through the insulation to restore the energy balance and stop heating up. The amount of heat radiated is proportional to the fourth power of temperature, so a 2.5% increase in radiant heat translates to ...1.025^(1/4) = 1.006... a 0.6% increase in temperature. Earth currently averages about 61F, or 289K in absolute terms, and a 0.6% increase of that translates to 1.8K, or about 3.2F.
A three degree increase doesn't sound terribly catastrophic all on it's own, but that's assuming nothing else changes, which isn't the case.
First off as things warm up we'll have more water vapor in the air, further increasing the amount of insulation.
More dramatically, the warming isn't uniform - the poles are heating much faster than the rest of the planet, which means those shiny white ice "mirrors" that currently reflect sunlight back into space before its absorbed are being replaced with dark sunlight-absorbing water. That means the planet is absorbing more energy from the sun, and it's going to heat up even further until it's radiating all that extra energy back into space as well.
And of course there's the rising oceans to contend with: water has a coefficient of expansion of 0.00012/*F, and the oceans have an average depth of about 12,100 feet. 12,100feet x 3.2*F x 0.00012/*F = 4.65 feet. So even without any icecaps melting, the ocean would rise that much. Which maybe doesn't sound too terrible, but something like 90% of the worlds population live within 10 feet of sea level. That's going to b
--- Most topics have many sides worth arguing, allow me to take one opposite you.