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Space Science

Kepler Spots "Perfectly Aligned" Alien Worlds 73

Posted by samzenpus
from the line-em-up dept.
astroengine writes "When NASA's Kepler space telescope started finding planets at odd angles to their parent stars, scientists wondered if our solar system's tidy geometry, with the planets neatly orbiting around the sun's equator, was an exception to the rule. That idea can be laid to rest thanks to an innovative use of the Kepler data which aligned three planets circling the sun-like star Kepler-30 with a giant spot on the star's surface. 'The planets themselves are not all that remarkable — two giant Jupiters and one super-Earth — but what is remarkable is that they aligned so perfectly,' astronomer Drake Deming, with the University of Maryland, told Discovery News."
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Kepler Spots "Perfectly Aligned" Alien Worlds

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  • I'm a software engineer so my knowledge is rather limited, but I'd have assumed that the orbits of planets would tend to be in the same plane as the spinning of the galaxy, so if you look at a mostly flat galaxy, you'll find mostly aligned orbits, and if a galaxy was more... "chaotic", the orbits would be likewise less aligned in respect with each other.
    • by AliasMarlowe (1042386) on Thursday July 26, 2012 @04:42AM (#40774711) Journal

      I'm a software engineer so my knowledge is rather limited, but I'd have assumed that the orbits of planets would tend to be in the same plane as the spinning of the galaxy, so if you look at a mostly flat galaxy, you'll find mostly aligned orbits, and if a galaxy was more... "chaotic", the orbits would be likewise less aligned in respect with each other.

      Well, each solar system has an invariable plane [wikipedia.org] perpendicular to its aggregate angular momentum vector. The rotation of the star and the orbits of the planets tend to be quite close to this plane. The exception is when the orbits have been perturbed by passage of an object of significant mass at an angle to the plane. Note that the invariable plane of any particular solar system in a galaxy is not necessarily similar to that of the galaxy as a whole, although aggregated over all solar systems in the galaxy they are the same.

      • Is there a reason this happens? I mean, what makes the orbits of planets around the sun different from orbits of man-made objects around the Earth? Do all the planets orbit in the same direction? Satellites and other space junk orbit retrograde and prograde, over the equator, poles, or anything in between, and with circular or elliptical orbits. Why don't the planets do this as well? Could it be that they've been orbiting for billions of years and all the planets orbiting different were consumed or des
        • My guess is that the gravitation pull between them (over said Billions of years) has pulled them into aligned orbits. But I am neither an astrophysicist, nor a rocket scientist, so salt may be required.
    • I think it's indeed an extension of the phenomenon you can see happening in those toy 2d simulators of gravity of stars and planets: start with a chaotic configuration, let it evolve for some time, and see how the stuff often evolves in one big central blob with possibly some circular orbits and short lived elliptical ones

    • IAMAP, but I'd have thought that the galaxy would flatten everything out to a certain degree, but as you move to smaller scales, local gravity conditions would take over, for example: the planets being more tightly bound to the sun than they are to the Milky Way as a whole.

      Q for a physic-y person - The earth orbits around the sun's equator, but its own equator is at an angle to the sun-planet plane (hence, seasons). Does the moon, then orbit around earth's equator (at an angle to the sun), or in the sam
      • by Tastecicles (1153671) on Thursday July 26, 2012 @05:30AM (#40774887)

        Disclaimer: IAAAA (I am an amateur astronomer).

        The moon orbits at a mean inclination of 5.something degrees to the ecliptic. If it were synchronised to the equatorial plane we wouldn't have nearly as many eclipses (lunar or solar) as we do. In fact, we'd have about 1/50 the number.

        • by oobayly (1056050)

          Can you explain why. Like a lot of things in life it seems to go against what one would think. For example, the transit of Venus occurs twice about every 120 years, I would have thought the transit would occur 1.6 times a year (365 / 225), if our orbits were in the same plane.

          • by Tastecicles (1153671) on Thursday July 26, 2012 @07:30AM (#40775563)

            Actually, I can.

            Even assuming that the orbital inclination of both planets were identical, those orbits undergo what's known as apsidal precession. This is the movement of apoapsis (the furthest point of the orbit) around the primary over time - the orbit orbits. For Earth this varies between 100,000-400,000 years, and is tidally dependent. Ergo, the relative angle of inclination between planets changes and while Earth is below the ecliptic, the orbit of Venus at that point, even if the planet was in the same orbital position (ie between Earth and Sol), may be above the ecliptic hence no transit occurs.

            This also happens with the Moon. Fortunately the systems are stable enough that we can predict when transits and eclipses will occur by concentrating only on dates and times where ascending and descending nodes of their orbits intersect the ecliptic. The great thing about the Moon is that it crosses the ecliptic exactly twenty six times per year, so we can predict with reasonable certainty from the off that solar and lunar eclipse patterns will repeat with fair precision every 6585 days, or every 223 Lunar orbits. (approximately 18 years).

            • addendum: think of a toy gyro. When you spin it, the pole (axis) starts to describe a circle in the air. Ignore that bit, look at the plane of the gyro - the edge represents the orbital plane relative to a fixed point in space (your eye). It is not only spinning, it is also describing an oscillation such that a fixed point in its orbit is moving in a sinusoidal motion. The wider the gyro, the slower this oscillation, but it is there.

      • Q for a physic-y person - The earth orbits around the sun's equator, but its own equator is at an angle to the sun-planet plane (hence, seasons). Does the moon, then orbit around earth's equator (at an angle to the sun), or in the same plane as the sun's equator (or some other plane entirely)?

        Along with the above answer to your question, I will also mention that Luna is the only sizable moon in the entire Solar System whose orbit is more closely aligned to the ecliptic than to the parent planet's equator.

      • by camperdave (969942) on Thursday July 26, 2012 @11:49AM (#40779049) Journal

        Q for a physic-y person - The earth orbits around the sun's equator, but its own equator is at an angle to the sun-planet plane (hence, seasons). Does the moon, then orbit around earth's equator (at an angle to the sun), or in the same plane as the sun's equator (or some other plane entirely)?

        First things first. There is no actual link between the equator of a body, and the orbits of the satellites of that body. The rotation of the planet, its orbital plane, the rotation of any moons or satellites of that planet, and the orbital planes of those moons are all independent from each other.

        Now, having said that, if a satellite formed by being spun off of a quickly rotating object, or if both the satellite and the planet both coalesced from the same rotating blob of matter, then there will be a tendency for the satellite to be in the equatorial plane. However, once the satellite is no longer physically connected, the orbital plane or the planetary axis can both shift independently of each other (through perturbations from other bodies). If a satellite was formed by an asteroid collision knocking the planet apart, then there may be some relationship between the planet's original spin and the satellite's orbit. However, it also greatly depends on the speed and angle that the asteroid hit the planet with, and of course, the collision could drastically change the axis of rotation of the planet. If a satellite was captured by the planet's gravity, it could be in any orbital plane, and could even orbit completely opposite to the direction of rotation of the planet.

        It takes a lot of energy to alter an orbital plane. So, just like the Earth spins and its axis is fixed in space, (pointing towards Polaris), so too the Earth's orbit is fixed in space. We call this the ecliptic. The ecliptic is inclined roughly 23.5 degrees from the plane of the Earth's equator. The equatorial plane of the sun is inclined roughly 7 degrees from the ecliptic. The plane of the lunar orbit is inclined at about 5 degrees from the ecliptic. Saturn's rings are along it's equator, and they are tipped 26.7 degrees. Uranus has its axis almost in the plane of the ecliptic at an inclination of 97 degrees. Venus's north pole is pointing south relative to ours (177.4 degrees).

        Of course, having said all that, there may be tidal effects and relativistic effects that a spinning gravity well may impart on a satellite to coax it into the equatorial plane.

    • by Coisiche (2000870) on Thursday July 26, 2012 @04:51AM (#40774747)

      I'd have assumed that the orbits of planets would tend to be in the same plane as the spinning of the galaxy

      If you consider that the Milky Way is not aligned with the ecliptic [wikipedia.org] then you should see that the assumption is erroneous with respect to the only solar system we understand well.

    • Re: (Score:2, Interesting)

      by Anonymous Coward

      It doesn't have anything to do with the spinning of the galaxy. Our ecliptic plane is not the same as that for the galaxy (60 degrees off).

      When a nebula collapses, there will be areas of lower and higher densities. Eventually this will impart an angular momentum. The rotation flattens out the protoplanetary disk [wikipedia.org]. Thus retrograde rotation or anything out of the ecliptic is very odd (such as the dwarf planet Pluto) and probably needs to be explained by events outside of the initial formation of the system.

    • no, it's more like the tip of a helicopter rotor at extreme velocities - rather than describe complete ellipses through space, as they would if they were flat onto the plane of travel, they describe a sort of mutant helix, with a cutting angle of about 60 degrees - so for part of its orbit, the Earth is actually travelling in the opposite direction in relation to the cosmic microwave background to the Sun. At one point during its orbit, the Earth actually slows down.

  • How can three planets in one solar system have any statistical significance in answering that question ??
    • I was thinking the same thing, in a limitless universe you are likely to find at least one instance of a "flat" solar system. However, in a limitless universe, there is likely a large number of "flat" solar systems.
    • by Anonymous Coward

      The null hypothesis would say that planets could orbit the star in any method. To reject it you would have to calculate the probability that 3 separate planets would have an orbit that would allow them to cross over the same sunspot. The probability isn't high, and 3 planets might be enough data to answer it with statistical significance. I'm not claiming to say that it is or not (it would be a pain in the ass physics problem). All that I'm saying is that the data could very well be the equivalent to rolli

    • if the universe is infinite, then there are an infinite number of stars. It follows that orbiting those infinite stars is an infinite number of planets. HOWEVER, and here's the paradox: if not all stars have orbiting planets, then the number of stars with orbiting planets is less than infinite, ie, finite. There are two countering assumptions right there: there is an infinite number of planets in the universe, there is a finite number of planets in the universe.

      Statistically speaking, this is significant, a

      • Re:mind-job, anyone? (Score:5, Informative)

        by johnw (3725) on Thursday July 26, 2012 @05:42AM (#40774959)

        HOWEVER, and here's the paradox: if not all stars have orbiting planets, then the number of stars with orbiting planets is less than infinite, ie, finite.

        Bzzzt! Fail - thanks for playing.

        Once you start playing with infinite numbers you have to be very careful with concepts like "less than" or "more than". Just because you can demonstrate that one set is in some way smaller than another infinite set does *not* demonstrate that the smaller one is finite.

        Consider the set of natural numbers - 1,2,3,4 etc. This is infinite. Then consider the set of even natural numbers - 2,4,6,8 etc. Clearly there are members of the first set which are not members of the second set, and so one might be tempted to conclude that the second set is in some way smaller, and therefore by your argument, finite.

        In fact one can set up a one-to-one mapping between the two sets:

        12
        24
        36

        etc. and thus both sets have precisely the same (infinite) number of members.

        • by Teresita (982888)
          But we can't set up one-to-one mapping between the allegedly infinite set of all stars, and the set of all stars without planets. We don't even know whether it would be a two-to-one mapping, or any x-to-one mapping. Some stars might have been divested of their planets by passing near other stars. There's no mathematical rule.
          • No, but we can set up a fraction. Let's say that 1/1000 stars have orbiting planets. That would be infinity/1000, which equals infinity. Still not finite. As another commenter noted, there is a one-to-one mapping of rational numbers (3/4, 1/72, 399/12, etc.) to integers.

            Or, as my sig used to say, "Space is big - really big. Better pack a lunch."

            • by Teresita (982888)
              My point is that you can't sit on your butt and create the rule, like you can between integers and fractions. You have to actually go out there and see what's there. And that's not even possible in principle, because by the time you get partway down your list, some of your previous mappings are invalidated by the fact that some systems lose planets and others gain planets.
              • by shaitand (626655)

                Actually you don't. At least not if you are starting from the assumption that there are infinite stars in the first place. No matter what the process is that results in flat star systems SOMETHING caused it, that something has a probability of occurring, all probabilities can be represented as a fraction of the sample set since in this case your sample set is infinity stars and any fraction of infinity is also infinity you don't have to actually know the probability of occurrence.

          • by sFurbo (1361249)
            Both numbers would be countably infinite, so there exists a 1-to-1 mapping between them. If we make a grid in 3D space, with earth in the origo, we can order the grid points. With a fine enough grid, we can them number the stars according to which grid point they are closest to. We can then number the planets lexicographically, after their stars number and their orbital period around the star. Planets sharing an orbit will give problems, but that is trivially solved as long as there is only finitely many pl
        • by tonique (1176513)
          Moreover, it can be shown that the rational numbers (eg. 1/2, 5/9, 314/999) have precisely the same number of members as natural numbers.
          • by sFurbo (1361249)
            This also goes for the algebraic numbers, the numbers that are roots in any polynomial.
        • Re:mind-job, anyone? (Score:4, Informative)

          by rbrausse (1319883) on Thursday July 26, 2012 @06:35AM (#40775209)

          Once you start playing with infinite numbers you have to be very careful with concepts like "less than" or "more than".

          Numberphile has a nice video about different types of infinity: http://www.numberphile.com/videos/countable_infinity.html [numberphile.com]

          • I always like introducing countable and uncountable infinities to people. The concept of one being larger than the other and that all sets of countable infinities are the same size (i.e. rational numbers, whole number, prime number, even numbers, etc) was always interesting. It is interesting watching them try to wrap their brain around that. I found that the easiest way for them to grasp the difference between countable and uncountable infinities is the difference between whole numbers and real numbers. A
            • by shaitand (626655)

              I'm not really sure why people have trouble with any of that. All of it seems like a logical given if one accepts infinity as a valid concept in the first place.

              Accepting that an infinity exists in the physical universe is the challenging part.

              • Possibly, but given how many people I have tried to teach that to it seems that there is a large swath that really struggle even when using the example of whole numbers vs. real numbers. I think the issue may be the abstractness of it, a countable infinity which tends to be the one most encountered still requires a fair amount of abstraction. Now introduce the concept of uncountable and some people just seem to give up or get very lost. When I first got introduced to the concept of different sized infinitie
            • by Raenex (947668)

              I found that the easiest way for them to grasp the difference between countable and uncountable infinities is the difference between whole numbers and real numbers. A countable infinity will always have a finite number of elements between any two elements (whole numbers) where as an uncountable infinity will have an infinite number of elements between any to elements in the set (real numbers).

              This is severely misleading, as there are an infinite number of elements between any two rational numbers, yet the rational numbers are still countably infinite.

              If you really want to explain it correctly, then the best way is talk about one-to-one correspondence. Having a one-to-one correspondence with the natural numbers is what it means to be countably infinite, and has a direct analogy to people counting with their fingers. Cantor's diagonalization argument shows why you can't count the reals, or more t

      • by gl4ss (559668)

        it would be extremely improbable that the only other flat system would be so close to earth.

        so your authority wouldn't be the same in casual observers view.

      • by mrbester (200927)

        if the universe is infinite, then there are an infinite number of stars. It follows that orbiting those infinite stars is an infinite number of planets.

        "Would you like a cheese and ham Breville?"

    • by jamesh (87723)

      It makes perfect sense in the realm of popular statistics... thousands of reports come out saying smoking/chocolate/coffee/alcohol/etc is bad for you. Then one comes out saying that there are some positive aspects of <product>, and the world thinks "Ah. So <product> is not so bad for you after all!".

      Still... in the scale of the galaxy, spotting another such system in the galaxy proves that earth isn't the _only_ one, and the chance that we've seen the only other well-aligned solar system in the

    • by trooper9 (1205868)
      Science by press release.
  • If only mechanical engineering had some breakthrough that could let us create engines that travel at light speed but sadly even light speed wouldn't be good enough to travel the whole wonderland. I hope we don't end up just looking at all these planets like sour grapes.
  • we'll show those blue freaks that unobtainium isn't fer plantin' trees on!

  • We all know (Score:5, Funny)

    by someones (2687911) on Thursday July 26, 2012 @05:32AM (#40774901)

    Universe is 2D.

    The 3D stuff is just to milk more money!

  • Where's Larry Niven's Kemplerer rosette in known space when you need it .....

    • by Teresita (982888)
      To hell with Larry Niven's Kemplerer Rosette, I wanna see W. B. Klemperer's Larry Niven novel.
  • by mrthoughtful (466814) on Thursday July 26, 2012 @06:35AM (#40775211) Journal

    The planets are merely aligned in the same plane - and not perfectly.

    When I first read the headline, I was expecting to read about a ring of planets sharing the same orbit - what would be equivalent to the first stage of maneuver for the development of a niven ring or even a dyson sphere. Now that would have been exciting news.

  • > innovative use of the Kepler data which aligned three planets...

    Well, in Superman III, we learned weather satellites could be used to control the weather, so why couldn't astronomy satellites be used to align planets?

  • I am still trying to make sense of the summary...

    The 3 planets are aligned perfectly with what? A spot on the surface of the star?
    (Maybe thats the shadow of another (very close in) planet).

    Reads on further
    "but what is remarkable is that they aligned so perfectly,' astronomer Drake Deming, with the University of Maryland,"

    So the planets are aligned with the University of Maryland ?

    Generaly the planets of our solar system are on the same plane as each other - except for Pluto, and that was kicked out for its

    • It's probably a very poor attempt at stating that their orbits are coplanar, in dumbspeak. I think these three planets separately transited the same starspot as viewed from Earth, which tells us something about their orbital planes.
  • The alignment does not prove they were formed from a rotating disk of gas. Planets in stable orbits around a sun with great tilts will gradually shift their orbits to nearly a common plane. This is caused by their own gravity affecting each other. How fast it happens depends on things like locations of larger planets and orbital timings. Note that while this is happening, their own rotational angle does not change. So the net result is planets with rotation planes not in alignment with orbit planes. T

  • When NASA's Kepler space telescope started finding planets at odd angles to their parent stars, scientists wondered if our solar system's tidy geometry, with the planets neatly orbiting around the sun's equator, was an exception to the rule.

    Any scientist wondering this should probably look up the terms selection bias and anthropic principle, and stop calling himself a "scientist."

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