Question in description. Why is this?!?
I still find it bizarre that we can find thousands of exoplanets in other solar systems and single out interesting asteroids in a mess of our main asteroid belt yet still not be able to find/confirm/disprove the existence of “the 9th planet’ in our very own solar system! Why is this?!
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answers:
To-Your-Health say: Planets are hard to detect visually because they don't emit any light. For example many theorists believe there is a 9th planet in our solar system, but its orbit is very far when revolving around our Star, bouncing off sunlight 160,000 times dimmer than Neptune and Pluto. Its easier for us to detect a planet from other host stars located in other galaxies and other regions of our Milky Way. How? When a object like a planet gets between us and its host star it dims slightly letting us know something is passing in front of it. Agronomists are constantly surveying our sky, which a overwhelmingly big, they can only survey small chunks. Many variables are needed where looking for planets by looking at its host star, dimming effect, gravitational measurements, influence over its surroundings. Once we find a star that might host planets we can lock on to that region pulling together all detecting resources investigating it farther.
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Ronald 7 say: Maybe because there is none
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busterwasmycat say: a good question. It is a matter of proportionality for the most part. we detect exoplanets primarily by change to intensity of light from the star (the planet has to be large enough to noticeably change light intensity) or through tiny movements in the star due to pull by nearby planets. We can't typically identify small planets, but it depends partly on how close the planet is to the star, too (same size planet blocks a lot more sun if closer, or pulls harder on the sun, and has a faster period of orbit so can be seen to repeat in a reasonable time frame).
Asteroids can be detected when they are large enough, bright enough, and close enough. We don't see all asteroids, but we do see a lot of them. They are close enough to the sun so that reflection is relatively high intensity light, and if they are big enough, we can see them (visibility is a size versus distance thing, of course).
With the outer Kuiper belt or neighborhood, which is about where there would be this hypothetical planet nine, sunlight is very weak so reflected light is very very weak. We are talking HUGE distances, like Jupiter to sun distances or more, where that unknown planet might lie out beyond Pluto. Pluto itself lies further beyond Neptune by a distance that is almost double the distance from sun to Jupiter, and this planet might be even that much further beyond Pluto. The rate of visible movement will be tiny per unit time (as seen from here) because of the size of the orbit of this object. Pluto takes about 250 years to complete its orbit. The "unknown" planet will take doubly that or more, so will be hard to see as moving, although we would have found it if it were easily seen despite that. We have been looking long enough that the motion would be obvious if it were an obvious point of light.
And this brings us to the real problem: We can barely see Pluto from here, and if there is a planet (and we do not know for certain that there is one), it is simply extremely tiny and faint from our view, even if it would be much larger than Pluto. There are innumerable similarly very faint objects, from fairly nearby small rocks (not even even big enough to be "asteroids") to very far away stars and all sizes and locations in between. Very much a needle in the haystack type of problem. Which one of these tiny dots of light would it be? Looking for a sand grain-sized insect on a beach where you don't even know if there truly is one, or not, and there is only the one, not thousands or millions.
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Jeffrey K say: A 9th planet would be very far from the sun so it would not be very bright. It would move so slowly that its motion would be hard to notice. If it was small, its gravity effect on the other planets would be tiny. All these things make it very hard to detect, and impossible to rule out.
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Chris Ancor say: There are other planets in our Solar system, but they are 'dwarf' planets such as Pluto. Nothing bizarre there.
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ANDY say: Many things are not clear in our solar system. Theories and hypotheses are becoming more and more as each day passes. This is because the number of scientists (astronomers, astrophysicists...etc) is continuously increasing. These people have their own ideas too─not only coming from what they have studied. The universe and its mind-blowing nature is becoming confusing and hard to grasp. Many decades ago, only limited number of people followed the slow growing knowledge about the universe. But today with TV shows almost daily and with talk shows on Internet, people are becoming more aware and need to know more. Scientists therefore want to fill in this gap and on their own start to study more and explain (if explainable, that is) the phenomena regarding, for instance, our solar system. The Oort Cloud is a good example. Does it exist or doesn't it? Does it have that inner part that looks like a doughnut and the outer part which is (supposedly) a sphere? Many questions have not been answered....and one of them is the ninth planet too! The Oort cloud has never been observed; neither has the so-called ninth planet. So let's just listen and see, but do not accept everything as being definitely correct.
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poldi2 say: If Planet X exists, its a LOT farther than asteroids in the main belt therefore very faint. And the volume of space to search is HUGE compared to the rest of the solar system.
Exoplanets are not found by direct observation, they are detected by their effects on their stars (which are visible).
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Paula say: We detect stars in other solar systems because we either:-
a) see the dimming of star light when one passes in front of the star
or
b) we see the slight movement of the star as the planet orbits the star
In both those cases we generally do not detect the planet directly. And mostly, these planets are relatively close to their star (so their influence on the star is significant).
The 9th planet in our solar system.
If it exists - lies far from our sun.
So it receives very little light from the sun making it hard to see it.
Plus
It has only a minimal effect on the movement of the outermost planets.
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quantumclaustrophobe say: There's indications one exists; it could be hard to find because it's small, there's very little light out there - and it's cold. There are still thousands of objects that orbit the sun we currently have no knowledge of - but I'm confident the ability to find (or disprove) these objects will come to us in time...
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Mark say: It is highly doubtful there IS a 9th planet in our solar system, and if there is, it probably has a highly ellipitcal orbit and is far far out now (in which case it would be invisible. The current detection of exoplanets relies on their crossing of the star and "wobble" of said star.
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To-Your-Health say: Planets are hard to detect visually because they don't emit any light. For example many theorists believe there is a 9th planet in our solar system, but its orbit is very far when revolving around our Star, bouncing off sunlight 160,000 times dimmer than Neptune and Pluto. Its easier for us to detect a planet from other host stars located in other galaxies and other regions of our Milky Way. How? When a object like a planet gets between us and its host star it dims slightly letting us know something is passing in front of it. Agronomists are constantly surveying our sky, which a overwhelmingly big, they can only survey small chunks. Many variables are needed where looking for planets by looking at its host star, dimming effect, gravitational measurements, influence over its surroundings. Once we find a star that might host planets we can lock on to that region pulling together all detecting resources investigating it farther.
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CarolOklaNola say: Limited observing time on specific telescopes. Observing times are s scheduled 3 to 5 years in advance. And the Sun may line up with the planet as well, so that makes it more difficult to search that area of the sky. In add Orion, there are maybe fewer people looking than you realize.
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