The Discovery of New Planets

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Bowser, Aug 24, 2015.

  1. Bowser Namaste Valued Senior Member

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    I was watching a YouTube video about the planets that have been discovered many light years from Earth. The detail in their descriptions left me doubtful about the actual science behind the discoveries. After all, how can you possibly glean so much from something that is tens of light years away? Wanting the truth, I asked my nephew who is working on his doctorate in astrophysics. He said, yes, they can determine quite a bit about distant planets from the light they reflect. Still, I find it hard to believe.

     
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  3. paddoboy Valued Senior Member

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    Extra solar planets are rarely detected directly.
    They are logically inferred by other methods such as, [1] The dimming of the parent star when the planet passes in front. This is called the transit method.
    The other is based on the scientific fact that bodies pull on each other.
    As a planet orbits its parent star, it will "tug'on the planet, making it"wobble"in its orbit...the closer a planet is, and the larger a planet is to the parent star, the larger and more noticable will be this wobble on the star.
    This explains why the first extrasolar planets discovered were super hot Jupiters, although as methods have improved, smaller and further away planets are being found.

    What I find amusing is your apparent distrust in what you have learned.
    Why is it so hard to accept?
     
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  5. Bowser Namaste Valued Senior Member

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    It's the detail in which they describe the planets. I feel as thought they are tickling my imagination with their claims. There was another YouTube video that I watched last week that inferred extremely complex descriptions of some of those planets.
     
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  7. paddoboy Valued Senior Member

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    There are far better, reputable sites than U tube videos.
    Yep, they are able to determine much, mass, size, etc, based on the simple laws of gravity and orbits.
     
  8. Bowser Namaste Valued Senior Member

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    Maybe so. I'm assuming that the YouTube videos are derivatives from the information being disseminated by our scientific community.

     
  9. tashja Registered Senior Member

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    Hi Bowser. Excellent questions. Let's ask Professor Ford:

     
    paddoboy likes this.
  10. Fraggle Rocker Staff Member

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    You have the tremendous good fortune of a close relative who's on his way to a PhD in this discipline. An actual expert in your own family!

    So why are you, (apparently) a layman, doubting him??? Are you skeptical of all experts? Do you ignore your physician's advice, instructions from your auto mechanic, the weather forecast?

    We're fortunate to live in an era when education is considered extremely important, so there are lots of people out there who know a lot more than we do.
     
  11. Bowser Namaste Valued Senior Member

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    I have the highest respect for the kid, he's a frickin genius. I suppose it's just hard to accept that we can extract so much information on an object that's so distant.
     
  12. paddoboy Valued Senior Member

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    The information that is extracted is simply based on known orbital laws and parameters.
     
  13. James R Just this guy, you know? Staff Member

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    Here's some more information about how exoplanets are found and how their properties are determined (from NASA):

    http://kepler.nasa.gov/
     
  14. Bowser Namaste Valued Senior Member

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    Well, thank you. I gave it a good look...interesting.
     
  15. Yazata Valued Senior Member

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    Bowser's trying to think for himself, Fraggle. He's trying to understand. That's a good thing, something to be applauded. Anyone who has ever taken (or taught) a university science class knows that professors usually try to push their students to do exactly that.

    What's the alternative? Assertions of authority to be accepted by faith?

    So stop trying to intimidate people who express curiosity about how astronomers know the things they say they know about extrasolar planets and stop tying to push Sciforums readers to conceive of science as if it was theology.
     
  16. Yazata Valued Senior Member

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    I think that the drawings of extrasolar planets that one often sees are artists' conceptions and shouldn't be taken literally. Nobody knows what the surfaces of these alien planets look like in that kind of detail. (We had enough trouble with nearby Pluto.)

    My old university (SFSU) was at the forefront of this research about ten years ago. (At one time, the majority of extrasolar planets known were discovered by them.) The method they used was very precise spectroscopic observations of stars thought to have extrasolar planets. As planets orbit their star, their gravity makes the star wobble slightly, motion that's visible by doppler methods if one has a sensitive enough spectrograph. The periodicity of these wobbles allows observers to indirectly deduce the mass and orbital parameters of whatever's making the star wobble.

    A feature of this method is that it's most sensitive to very high mass planets orbiting very close to their stars. And totally unexpectedly, many planets fitting this description were discovered, with masses as high or higher than Jupiter, orbiting their stars much closer than Mercury, the so-called 'hot Jupiters'. That's completely revolutionized astrophysical understanding of gas giant planets (they aren't always distant and cold) and the dynamics of how planetary systems form.

    Since then, another method for detecting extrasolar planets has come into use in the last ten years. This one looks for transits, the very slight periodic dimming of a star that occurs when an orbiting planet passes in front of it. This is the method the Kepler spacecraft used. It allows estimates of the transiting object's size and even, in some cases, some limited and fragmentary information about the chemical composition of the transiting planet's atmosphere (if any). If extremely accurate spectroscopic observation shows a very faint oxygen trace only when a planet is transiting, one could conclude that the oxygen is associated with the planet and not the star.

    But there aren't any detailed photos of these planets.
     
    Last edited: Sep 2, 2015
  17. Yazata Valued Senior Member

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    Last edited: Sep 2, 2015
  18. paddoboy Valued Senior Member

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    But obviously you as usual, in your usual stance for what you perceive as the underdog, [Bowser in this case] forget that we have also many who visit science forums such as this with an agenda...not to genuinly question or to try and understand science, but to trip up science in the hope of installing their deity [or alternative hypothesis] of choice.
    I'not saying Bowser is in this category, just that he has been informed with quite a few links which explained it reasonably well, including one Professor expert in this category.
    What Fraggle said was a genuine observation.
     
    Last edited: Sep 2, 2015
  19. Bowser Namaste Valued Senior Member

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    I can accept their capacity to determine its size and orbit, but I take exception when they start defining its atmosphere, planetary composition, axial rotation and more. I suppose I'm just a skeptic when people are talking about a speck that's light years away.
     
  20. paddoboy Valued Senior Member

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    People also took exception about landing on the Moon at one time.
    Perhaps you doubt the laws of gravity??/Or the data able to be gained from infra red spectroscopy?
    I suggest you read all the links again.
     
  21. Yazata Valued Senior Member

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    I don't think that any of those things are directly observed, with the exception of a few hints about some planets' atmospheres I guess. What's happening is that a lot of inferences are being made, based on what is known about these planets and known astrophysical and planetary science principles learned by observing bodies in our own solar system.

    Consider the 'hot Jupiters', the very massive planets that orbit very close to their stars, much closer in some cases than Mercury to the Sun. It's reasonable to expect that the rocky cores of these planets are tidally locked to the more massive star, such that their sidereal day (the time it takes the fixed stars to rotate once through the planet's sky) is equal to their orbital year (the time it takes for the planet to orbit its primary). In other words, we would expect one side of these planets to always face their star and the other side to always face away, based only on the physics.

    We can speculatively assume that the alien star's planetary accretion disk originally had composition much like our Solar system's, adjusted based on the alien star's spectral characteristics, particularly its metallicity. (It's known that there's a positive correlation between a star's metallicity, the heavy metals in its spectrum, and the chances of finding extrasolar planets there.) So we can hypothesize about these planets having rocky cores and about what the core's composition might be. (Even if we can't observe it and don't literally know.)

    If these are massive gas-giant planets, we can assume them to have atmospheres. Again, it's possible to start speculatively with the assumption that these originally were similar in composition to our gas giants here in this solar system. But the 'hot Jupiters' are receiving a massive amount of stellar radiation and heat. The sunward side of these hellish places might be thousands of degrees and highly ionized. So lighter molecules might be lost into space and that process would change the atmospheric composition. Lots of calculations have been done regarding that, but it's largely speculation at this point.

    And if one side of these planets is superheated while the other side is forever turned away from the star, one can apply earthly meteorological principles to try to imagine these planets decidedly unearthly weather. Those speculations have included tremendous supersonic winds blowing constantly distributing heat energy from the hot side to the 'cool' side. But again, nobody really knows.

    You are thinking like a scientist and that's a good thing to see.

    What do we actually know? How do we know it? What can we justifiably infer from our limited information? How plausible are those hypotheses? How might they someday be tested?

    It's important to keep speculation separate from fact in these kind of matters.
     
  22. paddoboy Valued Senior Member

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    What happens is that all this is a developing science, and just as the first exo planets were exclusively hot Jupiter giants at close orbital parameters [the easiest to discertain] Atmospheric detection is also improving all the time.
    Even now we can determine whether a planet has an atmosphere or not, simply by seeing the planet pass in front of its star, and observe the absorption rate if light from the star at specific wavelengths.
    Again the technology and ability is improving all the time, with better results.
    http://seagerexoplanets.mit.edu/research.htm
    Obviously correct, but let's look at reality.
    Certainly everything should be questioned, but by the same token it takes a Feynman to question an Einstein.
    Many links have been given. Infrared Spectroscopy has been around for quite a while...exoplanetary detection is improving as we speak. The laws of gravity and Kepler's laws of planetary motion are beyond question. Most of the information originally asked are explained by those. The detecting of the planets was the hard part. The detection of atmospheres is improving all the time and the composition of those atmospheres with them.
    All that is science in progress.
    Humility is a great asset for anyone...Einstein [the greatest most probably] had it in abundance.
    Arrogance is another matter. [Consider the links that have been given]
    The "exception" that Bowser says he has, smells like arrogance at worst, and an agenda at best.
    Perhaps though in defence of Bowser, he may have used an inappropriate word. Perhaps he means, he does not understand fully, which I hope is all that is in question.

    Speculation gets less and less speculative with further and further observations and more and more data. Hypothesis can become theories as observations are increased...Scientific theories become more and more certain as more and more observations continue to support that theory and the longer and longer it stands the test of time.
     
  23. paddoboy Valued Senior Member

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    Earth observations show how nitrogen may be detected on exoplanets, aiding search for life
    September 4, 2015 by Peter Kelley

    Finding and measuring nitrogen in the atmosphere of an exoplanet—one outside our solar system—can be crucial to determining if that world might be habitable. That's because nitrogen can provide clues to surface pressure. If nitrogen is found to be abundant in a planet's atmosphere, that world almost certainly has the right pressure to keep liquid water stable on its surface. Liquid water is one of the prerequisites for life.

    Read more at: http://phys.org/news/2015-09-earth-nitrogen-exoplanets-aiding-life.html#jCp
     

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