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1

This is a duplicated question but I think it fits better into astronomy than into physics. I'll try to answer all aspects of this question including the consequences. First, is it possible? Like already pointed out it is, like Pluto and Charon. But is is it possible for bigger planets, with the size of Earth. Well we didn't find this planet system jet, but ...


3

I answered this same question at physics.SE. I specifically joined this part of the SE network to address this duplicate question at this site. The astronomy community faced two crises with regard to what constitutes a "planet", first in the mid 19th century, and more recently at the start of the 21st century. The first crisis involved the asteroids. The ...


2

There is actually disagreement on this matter (within the IAU?). Dr. Alan Stern (lead of the New Horizons mission) for instance points out that "this rule is inconsistent" (e.g. see Pluto vote 'hijacked' in revolt). Not only has Neptune not cleared its path, but the same holds for Earth, Mars and even Jupiter. Jupiter has a set of asteroids (the Trojans) ...


5

Your premise is incorrect. We used to think Mercury was tidally locked, but since 1965 we now know it is in a 3:2 spin-orbit resonance, which gives it (long) days. Anything you read that says it is tidally locked is old, or itself using old reference material. Here are some quick sketches to show the orbit, relative orientation of the planet, and the ...


1

Like any other planet day/night will not flip immediately in a seconds. It will have its sunrise , noon and then sunset . The 1st year day refers to the time between morning and evening, and the 2nd half year of night (i.e. day in the other half) refers to the time between sunset and sunrise. Something similar happens in earth's noth pole and south.


0

There is a much easier way to do this. 1) Look up the length of the solar year in earth days 2) multiply the length of the years like this: Mercury year * Venus year * Earth year * Martian year * Jovian year * Saturn year * Uranus year * Neptune year 3) Divide by 365 to get earth years. And you have a time when they will align again ...


1

One of the STEREO satellites has been at the earth-sun L4 point, so we have "looked behind the sun", and verified that there is no counter-earth there. That was not the purpose of their mission though.


2

That situation would lead to heat transfer between the cold and the hot zones just like it happens here at the Earth. There is a paper on this that may help you: [...] heat transport from the day side to the night side of the planets efficiently reduces temperature contrasts [...] Source: http://arxiv.org/abs/1001.5117


1

This is just a partial answer (so far), but it will address at least part of your question. 1.To what temperatures the dark surface of such planet could be heated? Is there possibility of liquid water? Wikipedia gives a good estimate for this: 1,200 degrees Celsius. For a planet, that's pretty hot! Any water there would evaporate very quickly. In fact, ...


3

According to the Wikipedia article Counter-Earth, this idea has been floated around for millennia. However, modern day earth-bound techniques would easily detect a 'Counter-Earth' via the following (but not limited to) these methods: Gravitational perturbations would have been observed to have occurred on the other planets (terrestrial) As Earth's orbit ...


1

It would be detectable due to its gravity effect on other planets, comets and the Sun. Check these sites for further info: http://en.wikipedia.org/wiki/Counter-Earth#Scientific_analysis http://en.wikipedia.org/wiki/Lagrangian_point#L3


1

I don't know if this is what most astronomers use, but it is certainly a method that could be used. It also makes for some interesting photos. Gravitational lensing was one of the great predictions of Einstein's theory of general relativity, and was actually one of the first pieces of evidence for it - see the solar eclipse of 1919. Gravitational lensing is ...


0

they use Newton's law of universal gravitation, example gravity interaction between moon and earth , jupiter Jupiter and its moons, or sun and planets, you can find here , play with m1 and m2, G and r , to calculate , the key is r and G , get m1 for earth and m2 for any body in free fall , after get distance between earth and sun, and get m for the sun , if ...


1

We wouldn't feel the ejection of another planet off the solar system, since the attractive force of distant planets to Earth is very low. Only close encounters of Earth with other planets would cause noticeable up to severe changes on Earth. This would be caused mainly by tidal forces due to different acceleration for different parts of Earth, or by ...


1

Pluto will continue to be exactly Pluto no matter how we choose to categorize it. Fretting about the "proper" category is the tyranny of the discontinuous mind.


3

A lot of the push to have Pluto reinstated as the 9th planet is coming from Harvard, from their press release Is Pluto a Planet? The Votes Are In (Released September, 2014), they state the following outcomes from a debate: Science historian Dr. Owen Gingerich, who chaired the IAU planet definition committee, presented the historical viewpoint. Dr. Gareth ...


6

Yes, Pluto is still a dwarf planet. According to the IAU website, it still fits the criteria for a dwarf planet, fails to meet the criteria for a planet, and still carries the "dwarf planet" label, whatever its future status may be. I'm sorry I can't provide a longer or more detailed answer, but this is really a yes-or-no question. I hope this helps.


4

Unfortunately, the paper is not available on ArXiv (oh, what hardships we must overcome!), but I have found it here (http://www.slideshare.net/APODman2k/nature13156). In it, where the "900" figure is mentioned (2nd page, I believe), the authors (Trujillo and Sheppard) say that they ran simulations with the data already found and their additional findings, ...


0

With the volume and mass of a planet concludes are possible of its material composition. But there is more, for example auroras been observed at Jupiter. This is only possible if Jupiter has a magnetic field just like our earth. A magnetic field is a strong evidence for an iron core. The next point is, heavy materials accumulate in the center, so one could ...


5

As evidence of caverns detected on Mars, consider the following recent image taken from HiRISE instrument on the Martian Reconnaissance Orbiter : Image source: NASA Scientists believe that The hole appears to be an opening to an underground cavern, partly illuminated on the image right. Analysis of this and follow-up images revealed the opening to ...


6

Short answer: 1) Yes and no; 2) Yes, there is a supercritical fluid, of hydrogen. Long answer: It's fairly hot deep down in Jupiter; estimates range from 10,000 K to 24,000 K. You would think that anything in the core would be liquefied, and you could be right. Many models predict that Jupiter's core is rocky, but others predict that it is liquid. Still ...



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