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Being that close also offers us a better ability to examine it. The nearer the star, the more arc-seconds (or tiny fractions thereof) the star will appear in te

by mabbo 7y ago

Being that close also offers us a better ability to examine it. The nearer the star, the more arc-seconds (or tiny fractions thereof) the star will appear in telescopes. 12ly is ridiculously close! It also tells us something interesting. If we presume there's nothing special about our little corner of the universe, then the distance to the nearest potentially habitable planets gives us an estimate of how many habitable planets are out there. Only 12ly away and that one has maybe two habitable planets? That tells me the universe is teaming with potential homes for life.

joshuahedlund 7y ago
Yes 12 ly is amazingly close! > If we presume there's nothing special about our little corner of the universe, then the distance to the nearest potentially habitable planets gives us an estimate of how many habitable planets are out there I would put a slight caveat to this - I would argue we do know there's something "special" about our little corner of the galaxy, at least - we are in the continuously habitable zone - for example, there are billions of stars at higher densities closer to the core whose planets are likely uninhabitable due to toxic levels of radiation, GRBs, etc. So I actually might expect other planets near us to be more habitable on average than at least some other places in our galaxy. But I also think it's too soon to know how potentially habitable these planets are, until we have a chance to check a bunch of other things on the checklist, like the long-term stability of the sun's output and the planet's orbits, the frequency of destructive solar flares, the frequency of asteroid bombardments (if there are no Jupiters to absorb them), etc. Regardless the close distance should make it much easier to answer these sorts of questions than it would be far planets much farther away, and I'm excited to see what we can learn in the coming years.
- soulofmischief 7y ago
  Wouldn't each system's star do a decent job of pushing back extra-solar radiation? Up to a point, obviously, but it would seem that planetary background radiation levels aren't a direct function of solar density.
  - akiselev 7y ago
    It's not the density of the star but the density of stars. Dense clusters like those found in the center of our galaxy create a lot of secondary effects like bigger stars pulling matter away from smaller stars (creating lots of background radiation and matter floating around) and then stars plow through those interstellar clouds, creating deadly bursts capable of cooking entire planets, stripping away their atmospheres, etc. In the center of the galaxy, these events happen so frequently that it's extremely unlikely life on any of the planets would survive long enough to evolve beyond simple single celled organisms.
    - soulofmischief 7y ago
      I'm talking about the local solar density, not an individual star's density. Obviously that has little effect on the habitable zone of a planet. My question was about the ability of a system's star's own radiation to ward off extra-solar radiation and what kind of limitations we are aware of.
      - mixmastamyk 7y ago
        Believe you are thinking of solar wind? That might counteract another source, but don't believe light radiation would be affected.
        soulofmischief 7y ago
        Solar wind is a type of solar radiation. I thought perhaps a charged field of particles with an outward force could act at least partially as a shield in for some higher frequencies of electromagnetic waves.
      - snowwrestler 7y ago
        Electromagnetic radiation from one star does not repel electromagnetic radiation from other stars. If it did, we wouldn’t be able to see stars at night from the Earth.
- cced 7y ago
  I often hear about the LY unit of distance. Why is it that we are still discovering things which are close to us in LY units? Wouldn’t we discover things at a distance of 5xLY before discovering things at a distance of 100xLY?
  - Tuna-Fish 7y ago
    Things that are very luminous can be seen much further away than things that are very dim. This particular star is a tiny red dwarf, which is so dim we only just found the star itself in 2003. Our best planet-finding methods depend on finding signals in the light output of the host star. This is relatively insensitive to distance, but very sensitive to the properties of the star.
MR4D 7y ago
> Only 12ly away and that one has maybe two habitable planets? That tells me the universe is teaming with potential homes for life. This seems like the birthday problem in statistics [0] - that if you have 30 people, it's likely that two people have the same birthday. However, the problem that could also exist (in our corner of the galaxy) that everyone else has a birthday far away from ours, and nobody else shares a birthday on the same day with anyone else. (in other words, we happen to be the two people who share the same corner of the galaxy, but everyone else is far away and separate - i.e. no other clustering). Not disagreeing with you, and it does give us hope, but randomness is a bch that can make everything look different from how it actually is. [0] - https://en.wikipedia.org/wiki/Birthday_problem https://en.wikipedia.org/wiki/Birthday_problem
- dunkmaster 7y ago
  The birthday paradox works because you are looking for a pair that has the same birthday, regardless of what date that birthday is. It doesn't work in the habitable planet sense because you would be essentially locking the birthday to a fixed date.
  - metalchianti 7y ago
    Yes. How many people do you need in a room to be confident that one of them has the same birthday as you?
    - isostatic 7y ago
      How confident? Even with an even distribution of birthdays it's possible to have a billion people in the room that don't share your birthday. Very unlikely, but as there's only about 20 million people with your birthday, and 7 billion without, it's quite doable.
      - dwaltrip 7y ago
        "Very unlikely" is a severe understatement. With only 100k people, the odds of no one else having your birthday is 10^-120. With a million people, it is 10^-1192. And with a billion people... apparently, there are over a million zeroes between the decimal place and the first non-zero number. That is a pretty damn small probability. Here is the code I used in python 3: from decimal import Decimal print((Decimal(364) / Decimal(365)) ** num_people)
iamgopal 7y ago
One more benefit is, we are looking at very recent past instead of hundred and thousands year past in comparative other planted.
abtinf 7y ago
Light Year has a technical meaning, but it is so large that I can't relate to it at all. So I tried to figure out a different unit of measure, and I came up with what I call an "Earth Escape Year" or EEY. From Earth, the escape velocity for our solar system is 42.1 km/s. EEY is the distance traveled for 1 year at that escape velocity. It is the maximum amount of time it would take to reach an interstellar object directly launching from Earth -- any slower and you can't get there at all. 1 LY = 7,121 Escape Years. The upper bound time to reach these planets is about 85k EEY.
- dvdkhlng 7y ago
  Sorry, but this does not make sense in the way you intended. Your 42.1 km/s escape velocity "from earth" is the velocity you need, relative to the sun, at earth's orbital distance from the sun, to escape from the solar system [1]. As you get farther away from the center of gravity, your speed gradually slows down and reaches zero at infinity [2]. So your maximum amount of time for interstellar travel calculation is flawed and underestimates travel time by assumedly few orders of magnitude. [1] https://encyclopedia2.thefreedictionary.com/Solar+System+Escape+Velocity https://encyclopedia2.thefreedictionary.com/Solar+System+Esc... [2] https://en.wikipedia.org/wiki/Escape_velocity https://en.wikipedia.org/wiki/Escape_velocity

by mabbo 7y ago

joshuahedlund 7y ago

Yes 12 ly is amazingly close! > If we presume there's nothing special about our little corner of the universe, then the distance to the nearest potentially habitable planets gives us an estimate of how many habitable planets are out there I would put a slight caveat to this - I would argue we do know there's something "special" about our little corner of the galaxy, at least - we are in the continuously habitable zone - for example, there are billions of stars at higher densities closer to the core whose planets are likely uninhabitable due to toxic levels of radiation, GRBs, etc. So I actually might expect other planets near us to be more habitable on average than at least some other places in our galaxy. But I also think it's too soon to know how potentially habitable these planets are, until we have a chance to check a bunch of other things on the checklist, like the long-term stability of the sun's output and the planet's orbits, the frequency of destructive solar flares, the frequency of asteroid bombardments (if there are no Jupiters to absorb them), etc. Regardless the close distance should make it much easier to answer these sorts of questions than it would be far planets much farther away, and I'm excited to see what we can learn in the coming years.

soulofmischief 7y ago
Wouldn't each system's star do a decent job of pushing back extra-solar radiation? Up to a point, obviously, but it would seem that planetary background radiation levels aren't a direct function of solar density.
- akiselev 7y ago
  It's not the density of the star but the density of stars. Dense clusters like those found in the center of our galaxy create a lot of secondary effects like bigger stars pulling matter away from smaller stars (creating lots of background radiation and matter floating around) and then stars plow through those interstellar clouds, creating deadly bursts capable of cooking entire planets, stripping away their atmospheres, etc. In the center of the galaxy, these events happen so frequently that it's extremely unlikely life on any of the planets would survive long enough to evolve beyond simple single celled organisms.
  - soulofmischief 7y ago
    I'm talking about the local solar density, not an individual star's density. Obviously that has little effect on the habitable zone of a planet. My question was about the ability of a system's star's own radiation to ward off extra-solar radiation and what kind of limitations we are aware of.
    - mixmastamyk 7y ago
      Believe you are thinking of solar wind? That might counteract another source, but don't believe light radiation would be affected.
      - soulofmischief 7y ago
        Solar wind is a type of solar radiation. I thought perhaps a charged field of particles with an outward force could act at least partially as a shield in for some higher frequencies of electromagnetic waves.
    - snowwrestler 7y ago
      Electromagnetic radiation from one star does not repel electromagnetic radiation from other stars. If it did, we wouldn’t be able to see stars at night from the Earth.
cced 7y ago
I often hear about the LY unit of distance. Why is it that we are still discovering things which are close to us in LY units? Wouldn’t we discover things at a distance of 5xLY before discovering things at a distance of 100xLY?
- Tuna-Fish 7y ago
  Things that are very luminous can be seen much further away than things that are very dim. This particular star is a tiny red dwarf, which is so dim we only just found the star itself in 2003. Our best planet-finding methods depend on finding signals in the light output of the host star. This is relatively insensitive to distance, but very sensitive to the properties of the star.

MR4D 7y ago

> Only 12ly away and that one has maybe two habitable planets? That tells me the universe is teaming with potential homes for life. This seems like the birthday problem in statistics [0] - that if you have 30 people, it's likely that two people have the same birthday. However, the problem that could also exist (in our corner of the galaxy) that everyone else has a birthday far away from ours, and nobody else shares a birthday on the same day with anyone else. (in other words, we happen to be the two people who share the same corner of the galaxy, but everyone else is far away and separate - i.e. no other clustering). Not disagreeing with you, and it does give us hope, but randomness is a bch that can make everything look different from how it actually is. [0] - https://en.wikipedia.org/wiki/Birthday_problem https://en.wikipedia.org/wiki/Birthday_problem

dunkmaster 7y ago
The birthday paradox works because you are looking for a pair that has the same birthday, regardless of what date that birthday is. It doesn't work in the habitable planet sense because you would be essentially locking the birthday to a fixed date.
- metalchianti 7y ago
  Yes. How many people do you need in a room to be confident that one of them has the same birthday as you?
  - isostatic 7y ago
    How confident? Even with an even distribution of birthdays it's possible to have a billion people in the room that don't share your birthday. Very unlikely, but as there's only about 20 million people with your birthday, and 7 billion without, it's quite doable.
    - dwaltrip 7y ago
      "Very unlikely" is a severe understatement. With only 100k people, the odds of no one else having your birthday is 10^-120. With a million people, it is 10^-1192. And with a billion people... apparently, there are over a million zeroes between the decimal place and the first non-zero number. That is a pretty damn small probability. Here is the code I used in python 3: from decimal import Decimal print((Decimal(364) / Decimal(365)) ** num_people)

iamgopal 7y ago

One more benefit is, we are looking at very recent past instead of hundred and thousands year past in comparative other planted.

abtinf 7y ago

Light Year has a technical meaning, but it is so large that I can't relate to it at all. So I tried to figure out a different unit of measure, and I came up with what I call an "Earth Escape Year" or EEY. From Earth, the escape velocity for our solar system is 42.1 km/s. EEY is the distance traveled for 1 year at that escape velocity. It is the maximum amount of time it would take to reach an interstellar object directly launching from Earth -- any slower and you can't get there at all. 1 LY = 7,121 Escape Years. The upper bound time to reach these planets is about 85k EEY.

dvdkhlng 7y ago
Sorry, but this does not make sense in the way you intended. Your 42.1 km/s escape velocity "from earth" is the velocity you need, relative to the sun, at earth's orbital distance from the sun, to escape from the solar system [1]. As you get farther away from the center of gravity, your speed gradually slows down and reaches zero at infinity [2]. So your maximum amount of time for interstellar travel calculation is flawed and underestimates travel time by assumedly few orders of magnitude. [1] https://encyclopedia2.thefreedictionary.com/Solar+System+Escape+Velocity https://encyclopedia2.thefreedictionary.com/Solar+System+Esc... [2] https://en.wikipedia.org/wiki/Escape_velocity https://en.wikipedia.org/wiki/Escape_velocity