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NASA announces discovery of Earth-like planet with earth similarity index 0.98

nasa.gov

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Re: NASA announces discovery of Earth-like planet with earth similarity index 0.98

#111
post #100

ELI5: until we flew next to Pluto this month all we had is blurry 16-pixel images. How can we get such precise data on something millions of times further?

By induction rather than direct observation.

This page contains the measurements of the planet which might be the subject of the announcement; it gives you an idea of what kinds of metrics drive such an analysis:

http://exoplanetarchive.ipac.caltech.edu/cgi-bin/DisplayOver...

Re: NASA announces discovery of Earth-like planet with earth similarity index 0.98

#112
post #100

ELI5: until we flew next to Pluto this month all we had is blurry 16-pixel images. How can we get such precise data on something millions of times further?

Distance, time, and amount of light. All these things come into effect. The reason why Pluto took so long? Imagine trying to read a magazine with a pair of binoculars vs. somebody taking a picture right next to it. Which do you think will be easier to read?

We've had a pair of binoculars up in space for a while, but it was designed to see way further than Pluto. That is why we have always had blurry images.

Re: NASA announces discovery of Earth-like planet with earth similarity index 0.98

#113
post #100

ELI5: until we flew next to Pluto this month all we had is blurry 16-pixel images. How can we get such precise data on something millions of times further?

The similarity index measures things that can be worked out without needing a precise image of the planet. These are things like radius, density and surface temperature, which can be measured by examining its orbit and how much light from the star is blocked as it passes.

We can also determine the rough composition of its atmosphere by using different sorts of spectroscopy.

https://en.wikipedia.org/wiki/Astronomical_spectroscopy

Re: NASA announces discovery of Earth-like planet with earth similarity index 0.98

#114
post #37

Earlier quoted context omitted.

He says it in a few different ways in his lectures, but he believed that the psychedelic experience is so strange and full of content that, even if aliens landed on the White House lawn and it made the biggest story in the history of news, it's still not as astonishing as human neurochemistry. I'm not sure I agree, but I think it's good to keep this perspective in mind any time we find ourselves tempted to think of s…

Reality is really weird though. I really keep trying to think whether aliens existing would actually radically change my life, individually. On one hand, maybe, but on the other, probably not (and this is more likely). I feel like I already experience my existence like I am alien to everything that is not me, whether it is talking to a cat or a person or a tree, the whole thing is like 'reality blob' that I am not re…

Sartre's Nausea and Hesse's Steppenwolf tackles this theme beautifully.

Re: NASA announces discovery of Earth-like planet with earth similarity index 0.98

#116

If there is life on that planet, I wonder if it would be similar enough to host infectious diseases. I know the Apollo team was quarantined when they got back from the moon. As someone living on a continent that has undergone one apocalypse, I hope we have a similar procedure to prevent the spread of spacepox.

1) NASA already has such procedures.

2) Some types of molecules involved with life have chirality so the chances are small that our biological components as a whole would be compatible. (Think of it as several different kinds of "endianess." There would be a coin-flip for each molecule type with chirality.) So at worst, if we ate each other, we'd give each other molecular "indigestion."

More complicated operations, like that of viruses hijacking our cells to replicate themselves are probably right out. Invading foreign cells couldn't get very far in our bodies if all of their enzymes malfunction and they find our material "indigestible."

Re: NASA announces discovery of Earth-like planet with earth similarity index 0.98

#117
post #30

Earlier quoted context omitted.

Could you elaborate on what is so weird on that molecule?

It's a psychedelic type substance similar to LSD. What he meant is that the weirdest things you can ever experience is you on acid.

Eh, I guess it's a matter of personal perspective. Anything in a hallucination is a hallucination. It's not constraint to conform to reality.

For something to be REAL and weird automatically puts it on another level.

Re: NASA announces discovery of Earth-like planet with earth similarity index 0.98

#118
post #102
post #64

Earlier quoted context omitted.

Question: why is 'escape velocity' part of the Earth Similarity Index when, presumably, it's just a function of radius and density (which are also in the index)? I feel like I'm missing something.

It's a reasonable measure of surface gravity, which, along with an idea about the distance from the star it's orbiting, gives us a good idea about what kind of atmosphere we can expect (i.e. the lighter and the hotter a gas is, the easier it can escape a planet with a particular escape velocity), at least a basic idea about what kind of surface features we might expect and so on. It's also a parameter that is quick t…

Right, but the escape velocity is ~ radius * sqrt(density) anyway, and if you look at the equation for the Earth Similarity Index[0], each term has an associated weighting. So why include escape velocity explicitly, rather than just changing the weighting of radius and density? The weightings seem to be quite specific numbers too, so I imagine there's a methodology behind it, I was just curious as to the logic. (Also, e.g., why is the temperature weight 5.58? Wikipedia says the weighting is to 'equalise their meanings', but it's not clear to me what that means.)

[0] https://en.wikipedia.org/wiki/Earth_Similarity_Index#Formula...

Re: NASA announces discovery of Earth-like planet with earth similarity index 0.98

#119

Earlier quoted context omitted.

Crap, I was wrong. "S" doesn't stand for "Savings," it stands for "Standard." We really are in EDT. All the more reason to never specify it! :)

Welcome the world of pain that is timezones and DST... As someone who has had to write an extensive amount of deal with these two concepts they are the worst things ever. We should just abolish timezones, DST, and move to the International Fixed Calendar. Time sucks. I'm even in favor of moving to a seconds-based time unit like kiloseconds, miliseconds, etc instead of minutes/hours/days/weeks/months/years/etc. "Metri…

>We should just abolish timezones, DST, and move to the International Fixed Calendar.

You may find these links interesting:

- "So you want to abolish time zones" (http://qntm.org/abolish)

- "You advocate a ________ approach to calendar reform" (http://qntm.org/calendar)

Re: NASA announces discovery of Earth-like planet with earth similarity index 0.98

#120
post #100

ELI5: until we flew next to Pluto this month all we had is blurry 16-pixel images. How can we get such precise data on something millions of times further?

In order to take something akin to a photograph of a planet in another solar system, you'd need to build a network of telescopes with a diameter on the order of the size of Earth's distance from the sun. And in addition to being spread apart, they'd need to be pretty huge in order to capture enough photons from the target. (though of course there could be clever ways around this)

Here's a great explanation of the physics involved: http://www.askamathematician.com/2013/04/q-what-kind-of-tele....

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