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Space Earth

Are We Being Watched? Tens of Other Worlds Could Spot the Earth (eurekalert.org) 94

A group of scientists from Queen's University Belfast and the Max Planck Institute for Solar System Research in Germany have turned exoplanet-hunting on its head, in a study that instead looks at how an alien observer might be able to detect Earth using our own methods. From a report: They find that at least nine exoplanets are ideally placed to observe transits of Earth, in a new work published in the journal Monthly Notices of the Royal Astronomical Society. Thanks to facilities and missions such as SuperWASP and Kepler, we have now discovered thousands of planets orbiting stars other than our Sun, worlds known as 'exoplanets.' The vast majority of these are found when the planets cross in front of their host stars in what are known as 'transits,' which allow astronomers to see light from the host star dim slightly at regular intervals every time the planet passes between us and the distant star. In the new study, the authors reverse this concept and ask, "How would an alien observer see the Solar System?" They identified parts of the distant sky from where various planets in our Solar System could be seen to pass in front of the Sun - so-called 'transit zones' -- concluding that the terrestrial planets (Mercury, Venus, Earth, and Mars) are actually much more likely to be spotted than the more distant 'Jovian' planets (Jupiter, Saturn, Uranus, and Neptune), despite their much larger size. To look for worlds where civilisations would have the best chance of spotting our Solar System, the astronomers looked for parts of the sky from which more than one planet could be seen crossing the face of the Sun. They found that three planets at most could be observed from anywhere outside of the Solar System, and that not all combinations of three planets are possible.

Are We Being Watched? Tens of Other Worlds Could Spot the Earth

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  • No... (Score:5, Insightful)

    by Type44Q ( 1233630 ) on Friday September 08, 2017 @02:51PM (#55160491)
    No, but our ancestors might be.
    • Re: (Score:2, Informative)

      by infolation ( 840436 )
      The aliens would see our earth at the same time we see their exoplanet.

      By the time the light from the alien planet has reached our Earth to let us determine it's habitable, the light from our earth has reached them.
      • Re: No... (Score:5, Funny)

        by Type44Q ( 1233630 ) on Friday September 08, 2017 @03:02PM (#55160575)
        And the light doesn't even make a "whoosh" sound...
      • ...what?

        GP's point is that the light reaching them now doesn't allow them to see us as we are now, but as were x years ago where x is also the distance in light-years to the planet..

        • Re:No... (Score:4, Informative)

          by nukenerd ( 172703 ) on Friday September 08, 2017 @05:24PM (#55161393)

          TFA does not mention which exoplanets, but they will need to be relatively close to detect our transits. By "relatively close" we would be talking 10-20 light years - so us, not our ancestors (apart from the kids here).

          Anyway they would not need to look for transits when we are blasting radar beams and TV broadcasts in all directions, the latter of which which might be shit but nevertheless has strong self-correlation, such as we ourselves look for in the SETI project.

          • Re:No... (Score:5, Informative)

            by Kjella ( 173770 ) on Friday September 08, 2017 @06:38PM (#55161777) Homepage

            Anyway they would not need to look for transits when we are blasting radar beams and TV broadcasts in all directions, the latter of which which might be shit but nevertheless has strong self-correlation, such as we ourselves look for in the SETI project.

            With the distance and dispersion they'd still have to have an helluva big antenna pointing in our direction. So much so that AFAIK we're assuming they have better technology than we have, we couldn't pick up a TV broadcast from an alien world. If we point a radio telescope at them and "ping" them they'd get the message with current technology - assuming the antenna is pointing in the right direction, but that's quite different from an accidental pick-up of a signal intended for Earth.

            • With the distance and dispersion they'd still have to have an helluva big antenna pointing in our direction .... we couldn't pick up a TV broadcast from an alien world. If we point a radio telescope at them and "ping" them they'd get the message with current technology - assuming the antenna is pointing in the right direction, but that's quite different from an accidental pick-up of a signal intended for Earth.

              You should tell the SETI project to stop wasting their time then.

        • Re:No... (Score:5, Interesting)

          by dpilot ( 134227 ) on Friday September 08, 2017 @05:27PM (#55161421) Homepage Journal

          The first thing that will make Earth interesting is our Goldilocks position around our sun.

          The second thing that will make Earth interesting is our atmosphere. We have an "interesting" atmosphere.

          Both of those bits of information have been out there for a long time - longer than we've existed.

          • by Anonymous Coward

            >The second thing that will make Earth interesting is our atmosphere. We have an "interesting" atmosphere.

            Say the carbon-based life form that likes oxygen.

    • "No, but our ancestors might be."

      1. They are watching 'I love Lucy right now
      2. I find 'ancestor' offensive, you young whippersnapper

    • No, but our ancestors might be.

      You're not wrong. Based on the paper the closest planet we know of capable of observing the earth is 470ly away.

      HATS-11 b = 2954ly
      1RXS 1609 b = 470ly
      LKCA 15 b = 470ly
      WASP-47 b,c,d,e = 652ly
      WD 1145+017 b = 520ly

  • The majority of life has two suns not one.

    Our solar system is the anomaly.

    The fallacy is thinking that our system is the standard. It isn't -- it is the exception -- we need to stop pretending the human perspective is the only one that matters, or is even right.

    --
    Atheist, noun, a blind man arguing with the rest of the world that color doesn't exist.

  • by petes_PoV ( 912422 ) on Friday September 08, 2017 @02:53PM (#55160505)
    So why haven't these other worlds contacted us?

    Is it because they do not support life?
    That their live is not advanced enough?
    That they are trying to contact us, but we cannot detect their message.
    That it is a quality of advanced civilisations that they ignore each other (or defer contact until some defined "level" of civilisation has been reached).
    or are they on their way, right now.

  • My guess 100 % by the number of suns/exoplanets.
    Yet, the time factor plays a big role - billions of suns ? light years apart, mutual observations are delayed, are they still valid? Alpha Centauri for sure, any other's?

    • Re: (Score:1, Interesting)

      by Anonymous Coward

      Time is indeed an important factor. For one, the universe is only 13 billion years old; a baby by cosmological time scales. Earth could be the first, or one of the first, worlds where life has arisen. We might actually be all alone for now.

      Or if the universe is a simulation, then Earth might be the only place that either exists or has life coded into the sim.

  • by Anonymous Coward

    We have come from building Stonehenge to identifying exoplanets in an eye blink of time in the history of the universe. To speculate on aliens using the same techniques that we have come up with in our current lifetime is kind of silly. Either they aren't looking for exoplanets at all, or they've developed much more accurate measures to detect other worlds than solar transits. (Or perhaps "they" don't exist at all.)

  • by joe_frisch ( 1366229 ) on Friday September 08, 2017 @03:09PM (#55160619)

    They are looking for worlds that could see us using our current technology. Its an interesting study, but 100 years ago we would have tried (and failed) with a very different technique (direct telescopic examination). 100 years from now we may be using a completely different technology (solar system sized interferometers?, Some new trick to drastically reduce stray light in an image? X-ray telescopes? I have no idea) )

    We know nothing about alien technology (if it even exists). It may have followed similar paths to ours, but it might be wildly different.

  • Why this puff piece? I would hope there was more meat to the original paper.

    • Unfortunately, as of late articles about astronomy have been overrun with unnecessary injection of LIFE!!!!! It's no more than an attempt to make it more "sexy" - read clickbait - to the average reader and many online sites (ala The Daily Galaxy [dailygalaxy.com]) have grabbed that flag with ferver. And, as demonstrated with this very example, they are shoddy in their use of language because of it.
      • Eventually people get fed up with exciting headlines with no actual news associated with them. So it's a self-defeating game they are playing. Silly.

  • The wave front of the first broadcast of Wayne Newton's "Danke Schoen" is now 54 light years from Earth. The alien extermination fleet is probably already on its way.
  • Keep looking. Keep watching the skies"........The Thing from another World
  • by kenwd0elq ( 985465 ) <kenwd0elq@engineer.com> on Friday September 08, 2017 @03:26PM (#55160685)

    Considering that we detect planets that transit the parent star, and that we've detected thousands of them, AND that such an occultation is visible ONLY when the Earth is precisely on the plane of that system's ecliptic ... the only viable conclusion must be that planets around other star systems are LITERALLY as "common as dirt". It's likely that there are planets around MOST stars.

    • Considering that we detect planets that transit the parent star

      Not so. Exoplanets can also be detected by slight wobbling of the star they orbit.

    • According to a quick google, the current guess is 1.6 planets per star system in the Milky Way, for a total of 160,000,000,000 planets in the galaxy. And at least 1/6th of star systems are thought to have a terrestrial planet sized similar to Earth.

  • by Salgak1 ( 20136 ) <salgakNO@SPAMspeakeasy.net> on Friday September 08, 2017 @04:48PM (#55161159) Homepage

    . . .we're reality Three-V.

    ". . . as J'mm tests the native female with the Anal Probe, consider how Mutual of Andromeda protects your homeworld from pesky alien intrusions. . . "

    - Mrrl'nn Prk'nz, host of "Mutual of Andromeda's 'Wild Planet'"

  • Are allies astronomer watching you have sex?
  • We had better keep an eye on them and make sure they don't know we are here until they evolve.

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