NASA's Kepler Spots Its First Rocky Exoplanet 97
coondoggie writes "NASA today said its star-gazing satellite Kepler has identified its first rocky planet orbiting a sun similar to our own — 560 light years from our solar system. While not in an area of space considered habitable, the rocky planet known as Kepler-10b is never-the-less significant because it showcases the ability of Kepler to find and track such small exoplanetary movements. 'Kepler's ultra-precise photometer measures the tiny decrease in a star's brightness that occurs when a planet crosses in front of it. The size of the planet can be derived from these periodic dips in brightness. The distance between the planet and the star is calculated by measuring the time between successive dips as the planet orbits the star. Kepler is the first NASA mission capable of finding Earth-size planets in or near the habitable zone, the region in a planetary system where liquid water can exist on the planet's surface. However, since it orbits once every 0.84 days, Kepler-10b is more than 20 times closer to its star than Mercury is to our sun and not in the habitable zone.'"
Rocky (Score:2, Funny)
Headline (Score:5, Insightful)
The headline isn't flashy enough.
Should read:
NASA's Kepler Spots Hell 560 light years from earth and closing.
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I like it. If I had mod points, you would already be at a 5 - funny.
Of course, if it's tidelocked, there is probably a ring slightly on the dark side of the equator that isn't hellishly hot or cold.
Even if the temperature would be bearable, other conditions may be not. Hermian atmosfere [wikipedia.org] suggest that such a ring would probably show metal vapour atmosphere in the terminators line (in Mercury's case: sodium; in Hell-560's case, given a much closer proximity to its start, probably other - refractory elements - would contribute more, as the more volatile ones would be blown [wikipedia.org] away by the solar-wind).
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Minor details. I mean, if you can't handle breathing a little metal vapor (or building a respirator to filter it), what kind of space explorer are you?
Not quite about breathing only. Can you imagine yourself moving when a "thick layer of ice" of "condensed wolfram" forms on the joints of your space suit?
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Well, if it's a thick layer, that might be difficult. A thin layer on your visor might obscure visibility a bit. Naturally, the solution is to live underground, run pipes over to the hot side for power, and use UV lamps for growing your food in your underground oasis until the planet spirals into it's sun.
What? Closer to that hell of a core, heated to UV-hot by the core tides?
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Gotta be better than living in Houston. (old joke: If I owned Hell and Houston, I'd rent out Houston and live in Hell).
If it's tidelocked, there shouldn't be any significant tidal heating, and with minimal atmosphere, it should just have a really hot side, and a really cold side, with more moderate temps in between, just like Mercury.
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If it's tidelocked, there shouldn't be any significant tidal heating, and with minimal atmosphere, it should just have a really hot side, and a really cold side, with more moderate temps in between, just like Mercury.
Tidal locking doesn't preclude core tides if the core has a fluid component. Here's from a source in CA [nasa.gov] (they may know better than the guys in Houston - even if the californians aren't quite renowned for their sanity).
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That paper is about the moon, it's a 3 body system, the moon, earth, and sun. In a system, where one body is tide locked to it's primary gravitational influence but there are other significant gravitational influences, you can have tides, including core tides. However, in a system in which a body is tide locked to it's primary and has no additional significant gravitational forces (it's not gravitationally bound to, and doesn't have any relatively massive bodies gravitationally bound to it), there are no s
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p>If it's tidelocked, ... , just like Mercury.
BTW: Mercury is locked in a 3:2 spin-orbit resonance [wikipedia.org] - if somebody's selling you some real-estate on the Hermian day-night terminators, better buy the Broolyn bridge.
If you however decide to go for Mercury, take an insurance: they are saying that Mercury is bound to collide with Venus somewhere in the future (others say that even if you buy the Brooklyn bridge you have some chances to lose: Mercury may collide even with Earth [liberation.fr] - and that's because of Jupiter).
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Of course, if it's tidelocked, there is probably a ring slightly on the dark side of the equator that isn't hellishly hot or cold.
That's where the devil lives. Duh! Why would he want to spend his free time sweating, when he can go home, relax, and let the night-shift take care of the office?
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That's a terribly broad statement. Have you no imagination?
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Life at the anaerobic microbial level would be well suited to this, but higher organisms not
Not even those evolved from the "primordial soup of molten silica with the abundant phosporic and alumina nutrients in the presence of the rich cesium vapour atmosphere with the right amount sodium and that extra pinch of lithium, in the just-about-right-100m-tides created by their star which feeds them with the hydrogen and helium so generosly every day"?
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20x closer to sun than Mercury (Score:5, Informative)
That's less than 2 million miles, or .05 AU from the sun.
Quite toasty.
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What if it's a really weak sun?
Re:20x closer to sun than Mercury (Score:5, Insightful)
What if it's a really weak sun?
We already know what the star is like. It's about on par with the Sun so the planet is probably molten on one side and fairly cold on the other given that it's probably tidally locked .
Re:20x closer to sun than Mercury (Score:5, Funny)
But its a dry heat.
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Pedant; 2 million miles is about 0.02AU, not 0.05AU. 1 AU is the average Earth-Sun distance which is about 93,000,000 miles.
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That's less than 2 million miles, or .05 AU from the sun.
Quite toasty.
They're quoting a likely surface temp of 2500F - more like molten than toasty.
Plane (Score:4, Insightful)
Re:Plane (Score:5, Informative)
Yes. Mostly. For this (transit photometry) method.
There are several methods of finding an extrasolar planet.
Briefly:
1) Pulsar variations: If a planet orbits a pulsar, the pulsar's timing will vary in a manner that can be detected by us, and we can use 3-D trig to figure out relevant parameters such as mass and radial distance.
2) Doppler shift of a star's emission lines: If a planet orbits a solar-type star, we can use the star's doppler shift of certain spectra to determine the various parameters of the body (or bodies) orbiting the star.
3) Gravitational microlensing: If two stars align just right to create a microlensing effect, the star further from us will show up as several images or as an Einstein ring, and its brightness will be amplified. If there's a planet orbiting the star that's closer to us, those mirror images or the ring will change with time, and they will be a bit brighter than without the planet.
4) Astrometry (measurements of the variation of a star's position relative to the "plane of the sky"): If there's a massive planet with an eccentric orbit, the star will orbit a barycenter that's outside of its mass, causing the star to move relative to the background.
5) Direct imaging: with certain techniques for processing stellar imagery, we can detect whether or not there's a planet reflecting some of that star's light to us.
6) Transit photometry: observing the star's brightness decrease as the planet eclipses the star. This works best for planets with a perfect orbital alignment with us, but we can still detect and work out minimum values for the relevant parameters.
7) Radio flux: Certain jovian-type planets can emit radio fluxes that differ significantly from most stars. These fluxes can be difficult, though not impossible, to detect from the interstellar noise.
There are more methods...
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Yes, but I think that's fairly common due to conservation of angular momentum in the Milky Way and all of the solar systems that formed within it. Our solar system is tilted however.
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So this means if a planet orbits a sun in any other plane than the one that happens to line up directly with us, it wont spot anything? Wouldn't that be...most of space?
Yes. This method will only spot a tiny minority of the planets it could potentially spot if the angles were different. The galaxy would have to contain many millions of stars for this to be at all useful. But, as it happens... ;)
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Most of space is actually empty.
But yes, only a tiny fraction of all stars will have transiting plantes. Kepler makes up for that by looking at lots of start simultaneously. Even if only 0.5% of all stars have transiting planets, you're still likely to find quite a few if you look at thousands of stars.
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Wonder what the discovery curve is expected to be? (Score:5, Interesting)
To me it seems that it is going to be a very slow start (apart from these totally hotrock type planets with insanely quick orbit) but then the taps will be turned on and they will start finding exponentially more and more?
Re:Wonder what the discovery curve is expected to (Score:4, Informative)
And that is only to find a single transit. Then add another year to get the orbit, probably another year at least to confirm.
Well, probably yes, assuming they're looking for yearly (like Earth's) orbits. Makes a bit of sense, but an Earth-like planet might be closer or further away from its host star, and be perfectly OK for liquid water, life, all that (depending on the host star's energy output). Probably not very different from a year though, it rather depends on the sizes (mass and orbital radius) involved.
As for the confirmation, it might not get that long; since the dip might be a starspot or a different agent, a Doppler effect study (or astrometry, in the future) might confirm or dismiss it because, to some extent, different methods of detection can be used on the same source for confirmation. Though, on the Kepler mission, I think the confirmation is 'included' and the timeframe is set for 3 years.
To me it seems that it is going to be a very slow start (apart from these totally hotrock type planets with insanely quick orbit) but then the taps will be turned on and they will start finding exponentially more and more?
Hopefully yes. For the moment the methods of detection are biased- each of them is capable of locating specific groups of planets based on two parameters, those parameters being the planetary mass and its distance from its host star- there's also gravitational lensing that can 'see' better, but its a one-timer.
Encouragingly enough, if one plots the findings so far (mass vs orbital distance) it is not hard to imagine that the so far covered areas will start to expand. My point being that, before the Kepler mission, 'hot Jupiters' kept being the majority of bodies discovered, because they are the only ones we had the means detecting- Kepler has been watching the same patch of space, and it should see more than 'hot Jupiters' (provided they're out there and we are going around this the right way).
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To me it seems that it is going to be a very slow start (apart from these totally hotrock type planets with insanely quick orbit) but then the taps will be turned on and they will start finding exponentially more and more?
Given exponential time and budget, I hereby state that "the Kepler programme" is theoretically able to eventually detect all the planets in this and nearby galaxies.
(seriously... this is to say that "the law of the most restricting factor" will seriously skew the "discovery curve" you mention... just don't hold your breath).
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It's so very exciting! I'd die to see a real telescopic close-up of the first closely observed exoplanet! Generations would have passed before we reach that stage of discovery though. For now, the artist's concept will do nicely as wallpaper :-)
I wonder (Score:2)
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Two ways:
1. The graph of light intensity vs. time has a particular shape for perfectly spherical objects such as planets passing in front of a star.
2. Those doppler shifts would not be affected by a sun-spot, and measurements of this kind aren't always verified by doppler shift methods.
So to find earth... (Score:1)
Re:So to find earth... (Score:4, Informative)
So to find a truly earthlike planet, won't they have to focus on a single star for more than a year in order to detect the planet passing the star more than once?
Yep. And for Jupiter-like planet we'd need to be watching it for hundreds, if not thousands of years if we were to use this method.
What if the planet's orbit never aligns to eclipse the sun?
Then we would never detect it via this method.
What if there are two or three planets in very similar orbits?
It depends on how well they are aligned. Even if they're perfectly aligned, we're liable to see the first one before the second or third one as it passes in front of the star. If they are even slightly out of phase, they will eventually be in an orbit in which we see all three distinctly. In any case, the radius and shape of the occlusion in front of the star is determined by the shape of the light intensity vs. time graph. Circular disks have a very specific light occlusion shape, while abberant occlusions have different shapes.
Is there a doctor (of astronomy) in the house? (Score:2)
I don't understand how a planet could be whipping around its primary once every .84 days, in an orbit 20 times closer than Mercury is to the Sun, and not be torn apart by tidal forces.
What am missing?
Re:Is there a doctor (of astronomy) in the house? (Score:5, Informative)
The Roche limit is defined as:
d = R ( 2 rhoM/rhom) ^ (1/3).
d is the orbital distance.
R is the primary (star in this case) radius.
rhoM is the primary's density.
rhom is the satellite's density.
If rhom > 2 rhoM, d is inside the radius of the primary.
The star in question is similar to ours, so I'll use our sun's density: 1.4 g/cm^3
The planet's density is 8.8 g/cm^3.
Therefore, the roche limit is within the star's radius and the planet will not be ripped apart.
This presumes a nearly circular orbit, which is good enough for this case.
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Thank you very much for that excellent explanation. It's exactly what I wanted to know.
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I don't understand how scientific articles manage to continually abuse terms like "smaller than," "slower than," "closer than" and other "lesser than" variants, when they fail to specify a reference point.
It's 20 times closer to the Sun than Mercury is, compared to what? Compared to Earth's orbit? Venus' orbit? No; I do understand that what they mean is that the average distance of kepler 10b from its sun is 1/20 that of Mercury's average distance from our own Sun, but that I can grok their lousy article d
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I presume you're complaining about the article linked to by Slashdot. That's not a scientific article; that's a popular science article.
Here's NASA's report, which isn't much better. I can't find the actual journal article yet.
www.nasa.gov/topics/universe/features/rocky_planet.html
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"It's 20 times closer to the Sun than Mercury is, compared to what?" you reworded the statement to remove one item in the comparison and then complained they didn't include that item. The actual statement is "it is more than 20 times closer to its star than Mercury is to our sun."
Note there's an additional object in their statement and hence "compared to what" is well defined.
Or is it that you don't like "20 times closer to" and would prefer "20 times further away than" (and the order swapped)?
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Scientific articles don't. News articles do.
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in an orbit 20 times closer than Mercury is to the Sun.
What am missing?
This is the part I don't get - does it mean 1/20th? I hate it when people write about "times", a word meaning multiples, to describe something as less! Isn't it much clearer to say Mercury is 20 times farther from our sun than this planet is from its?
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> This is the part I don't get - does it mean 1/20th?
I think that's what newsies usually mean when they say something like "20 times closer".
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Of course it means 1/20th.
Yes people who know mathematics hate that, but it's very common English usage.
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Of course it means 1/20th.
Yes people who know mathematics hate that, but it's very common English usage.
So is ain't. And I tell ya, it ain't right!
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... Isn't it much clearer to say Mercury is 20 times farther from our sun than this planet is from its?
No. It just maps onto a mathematical statement more directly, but the meaning is perfectly clear in either case to a fluent speaker of the English language. Twice as close means half as far, etc.
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If Bob lives two miles from Lisa, and Fred moves in one mile away, Fred is not twice as close as Lisa.
He's 1/2th the distance. 50% the distance. Whatever.
But he is not twice as close.
You can't even define close. What value does close have? So you can't say Fred is twice something that can't be defined anyway.
Orbits (Score:2)
How will we discover planets that are orbiting stars, but that do not cross in front of our field of view?
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With difficulty. We can try to detect the slight wobble induced in the star by the planet or attempt to image the planet directly. AFAIK both are beyond current technology for Earth-sized planets.
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All these telescopes are looking for planets that orbit in front of their suns, relative to our viewing angle. We only know they are there from the shadow they cast toward us.
How will we discover planets that are orbiting stars, but that do not cross in front of our field of view?
Whoa, but this is elementary... just pay them a visit. Until then, discovering them isn't much of a benefit anyway, or is it?
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The benefit, besides "Science!" is that we can start filling in values for the Drake Equation, even if we have to do a bit of mathematical calculation first to figure out how many planets we're probably missing.
While not in an area of space considered habitable (Score:1)
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They mean its proximity to the sun, the so-called "habitable zone" that everybody wants to talk about, regardless of the type of planet.
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I do not profess to know anything, but I never quite understand it when people go on about a planets ability - or lack there of to sustain life.
Now I (think I) understand the habitable zone, but just because something is too hot or too cold for our liking, does that really mean it would be too hot or cold for whatever may evolve independently of what has evolved here on earth?
The search for water is often associated with the search for life. Have I watched too much bad SciFi and read too many comics that I
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If we assume that life can be anything anywhere how do we decide where to look and how will we know it if we find it? We have one example of a habitable planet. We are narrowing the search by looking for similar places. We have limited resources. Why look for silicon-based life instead of carbon-based life when we don't even know if the former is possible but are an example of the latter?
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Oh, you're not "very wrong."
We can only recognize life as we already understand it. A common medical exam question is to define life. A common graduate school exam question is to define life. How do we do that? Based on what we know.
We know that life (as-we-know-it) requires a few conditions, so we look for planets that could support those conditions.
Nobody thinks that's the only place to find life, but it's probably the easiest place to find life that we would understand...
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". .not "very wrong" Can I show this to my wife?
But thank you for the clarification.
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I make no guarantees to that assertion's applicability other than in the context in which it was originally intended.
The "holy grail" (so to speak) right now is finding evidence for ANY life outside of our planet. Doing so would change our relationship with the universe in many ways (even though most relevant scientists are much less agnostic than they should be when it comes to the question of whether life exists elsewhere in the universe). Once we find life in one place not on Earth, we'll be much more
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I have always felt that people put too narrow a view on what life is or could be.
You're reading too much into it if you're thinking they're limiting their view on what life is or could be. If I tell you I've just arrived in the city and am looking for good Italian restaurants, it does not follow that I am assuming only Italian food exists or could exist. It's just the kind I'm most interested in finding at the moment. The "habitable zone" is the zone that could support all the life we've ever detected. If we detect new forms of life, the zone will get bigger. There's no a priori as
'habitable zone' .. (Score:3)
.. not my favorite term, but a way to derive it in front of astrophysics students is to assume a planetary body, no atmosphere, figure out its surface temperature, and demand it to be 'within liquid water limits'.
Now, since one may very correctly inquire, "liquid water without atmosphere? Are you on crack? And do your math, some planets are obviously not in it like, well, THE ONE WE'RE STANDING ON", I will have to add that I have been in two conferences so far, and 'habitable zone' seems to be more a popula
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.. not my favorite term, but a way to derive it in front of astrophysics students is to assume a planetary body, no atmosphere,
In my graduate studies, we defined and derived it with and without an atmosphere.
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Question:
Does the Moon qualify as being in the habitable zone, when you look at it in isolation? With an equator temperature of 100K to 390K and a mean of 220K [wikipedia.org], I would say no.
A mean temperature that is about the same as that of the interior of Antarctica [wikipedia.org], and extremes that almost dip low enough condense oxygen (at 1 Atm) and high enough to boil water (at 1 Atm).
Yet, once we add an atmosphere (Earth), we end up with much more reasonable temperatures. Minimum of 184K, mean of about 288K and max of about 330K
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equator temperature of 100K to 390K and a mean of 220K, I would say no.
So would I
Yet, once we add an atmosphere (Earth), we end up with much more reasonable temperatures.
My point exactly. Furthermore, if the atmospheres where formed on the same time the planets did, after they 'settle' (i.e. after they stop escaping into space) a 'lid' is formed around the planet that makes it more difficult for heat to escape.
On the other hand, while the atmospheres are still settling, they are much more optically thick so no cooling occurs (except, of course, from the fraction of the atmosphere escaping to space carrying heat with it). And from what I've read, nearly Earth-sized
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Yes, the moon is within the habitable zone, but it's not habitable. If we discover a rocky planet in the habitable zone of another star, the first thing we'll be looking for is an atmosphere (which is quite a bit more difficult than finding the planet, but techniques are being developed and tested). If we discover evidence for an atmosphere, the habitability of that planet jumps into a realm that is much more interesting. Then we start looking for evidence of certain gases in the atmosphere (water vapor,
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In my graduate studies, we defined and derived it with and without an atmosphere.
Interesting- how did you do that in the atmosphere case? Multiply it with a factor to inhibit cooling, after/while you get the temperature balance?
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Well, first, let's go into some history.
A habitable zone around a main sequence star was originally (1959) defined as a (virtual) ring around that star in which at least 10% of the surface of a planet, with an Earth-like atmosphere, in that zone had a mean temperature of between 0 and 30 C with extremes not exceeding -10 and 40 C. This is appropriate for humans to survive.
The zone was quickly expanded to mean wherever liquid water was stable. The term "biostable" was employed to mean where liquid water wa
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OK so I see it was a project, not just an extra factor or two. Interesting to hear about the story of the 'habitable zone', and also the distinction between 'habitability' and 'biostability'- it is not hard to envision that a 'biostable' planet can still be colonized (though some science fiction technology is going to be needed!). Just a few points though;
at least 10% of the surface of a planet, with an Earth-like atmosphere, in that zone
Well, to get 10% of a planetary surface, that would be some fraction of its radius in terms of distance; on Earth-like planets that would be a couple of t
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I'm not sure what you mean when you talk about 10% of a planetary surface and AUs.
Earth's surface area is 5.1x10^8 km^2. 10% of that is, obviously, 5.1x10^7 km^2. The land area of the US is about 9.8x10^6 km^2, so we're talking about 5-times the land area of the US. None of this has anything to do with distance from the star, just to do with the radius of the planet.
But, as you say, the point of 10% isn't that it's a special number; it's a starting point. Notice that this definition explicitly excludes
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> ...20 miles from the surface of a star...
Not 20 miles. "20 times closer to its star than Mercury is to our Sun". That would put it somewhere around 1.5 million miles out.
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When referring to planets it always means "where liquid water could exist".
Because we have an ever so slight bias towards life as we see it on Earth.