Starship Asterisk*

dougettinger wrote:Has anyone heard about the approaching brown dwarf star supposely recently discovered by southern polar region telescopes ?

This star orbits our Sun about 30 degrees from the ecliptic plane and soon will be at the periapsis location for itself and our Sun. It was not known to exist because it was a very dark brown dwarf star hard to see without infrared means. This star has several planets orbiting itself with the possibility that one of more of its outer planets might travel inside the orbits of the Sun's own planets. The claim is made that the star and some of the planets have been photographed. Does anybody have contact with any of these viewing stations in the south pole regions in order to confirm any of this amazing information ?

Chris Peterson wrote: Sounds like a load of crock, to me. I very much doubt that any stars are orbiting ours. The Planet-X/Nibiru nutjobs are always proposing this kind of stuff, but it makes no sense in terms of orbital dynamics.

Proxima Centauri (Latin proxima: meaning 'next to' or 'nearest to')[9] is a red dwarf star approximately 4.2 light-years (3.97 × 1013 km) distant in the constellation of Centaurus. It was discovered in 1915 by Robert Innes, the Director of the Union Observatory in South Africa. The star is the nearest star to the Sun.[8] Its distance to the second and third nearest stars, which form the binary star Alpha Centauri, is only 0.21 ly (15,000 ± 700 astronomical units [AU]).

dougettinger wrote:Does anybody have contact with any of these viewing stations in the south pole regions in order to confirm any of this amazing information ?

Forget about Planet X. Does anyone have any knowledge of a newly discoverered brown dwarf very close to Earth in the southern skies ? Speaking of orbital dynamics - how many Au's distant is Proxima Centauri from Alpha Centauri in its orbit around the larger star?

dougettinger wrote:This star orbits our Sun about 30 degrees from the ecliptic plane and soon will be at the periapsis location for itself and our Sun. It was not known to exist because it was a very dark brown dwarf star hard to see without infrared means. This star has several planets orbiting itself with the possibility that one of more of its outer planets might travel inside the orbits of the Sun's own planets. The claim is made that the star and some of the planets have been photographed.

BMAONE23 wrote:From the great and powerful WIKI

Proxima Centauri (Latin proxima: meaning 'next to' or 'nearest to')[9] is a red dwarf star approximately 4.2 light-years (3.97 × 1013 km) distant in the constellation of Centaurus. It was discovered in 1915 by Robert Innes, the Director of the Union Observatory in South Africa. The star is the nearest star to the Sun.[8] Its distance to the second and third nearest stars, which form the binary star Alpha Centauri, is only 0.21 ly (15,000 ± 700 astronomical units [AU]).

dougettinger wrote:Why or where did I get the idea that Alpha, Beta, and Proxima Centauri was a three star system with Proxima being the closest to Earth? Certainly Proxima is not part of a three star system if it is 15,000 AU away from the other two stars.

dougettinger wrote:
Perhaps I do not know the scales of multiple star systems. Most observed binaries are within the orbit of Mercury or Venus. Would not a 15,000 AU separation rule out any significant gravitational attraction between two stars?

http://en.wikipedia.org/wiki/Proxima_Centauri wrote:

From Proxima Centauri, the Sun would appear as a bright, 0.4 magnitude star in the constellation Cassiopeia.

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This illustration shows the comparative sizes of (from left to right) the Sun, α Centauri A, α Centauri B, and Proxima Centauri

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<<From the time of the discovery of Proxima, it was suspected to be a true companion of the Alpha Centauri binary star system. At a distance to Alpha Centauri of just 0.21 ly Proxima Centauri may be in orbit about Alpha Centauri, with an orbital period of the order of 500,000 years or more. For this reason, Proxima is sometimes referred to as Alpha Centauri C. Modern estimates, taking into account the small separation between and relative velocity of the stars, suggest that the chance of the observed alignment being a coincidence is roughly one in a million. Data from the Hipparcos satellite, combined with ground-based observations, is consistent with the hypothesis that the three stars are truly a bound system. If so, Proxima would currently be near apastron, the farthest point in its orbit from the Alpha Centauri system.

If Proxima was bound to the Alpha Centauri system during its formation, the stars would be likely to share the same elemental composition. The gravitational influence of Proxima may also have stirred up the Alpha Centauri protoplanetary disks. This would have increased the delivery of volatiles such as water to the dry inner regions. Any terrestrial planets in the system may have been enriched by this material.

Six single stars, two binary star systems, and a triple star share a common motion through space with Proxima Centauri and the Alpha Centauri system. The space velocities of these stars are all within 10 km/s of Alpha Centauri's peculiar motion. Thus, they may form a moving group of stars, which would indicate a common point of origin, such as in a star cluster.

Among the known stars, Proxima Centauri has been the closest star to the Sun for about 32,000 years and will be so for about another 33,000 years, after which the closest star to the Sun will be Ross 248. Proxima will make its closest approach to the Sun, coming within 3.11 light years of the latter, in approximately 26,700 years. Though Proxima Centauri is the nearest bona fide star, it is still possible that one or more as-yet undetected sub-stellar brown dwarfs may lie closer.
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In 1915, Robert Innes, Director of the Union Observatory in Johannesburg, South Africa, discovered a star that had the same proper motion as Alpha Centauri. He suggested it be named Proxima Centauri. In 1917, at the Royal Observatory at the Cape of Good Hope, the Dutch astronomer Joan Voûte measured the star's trigonometric parallax and confirmed that Proxima Centauri was the same distance from the Sun as Alpha Centauri. It was also found to be the lowest-luminosity star known at the time. The first accurate parallax determination of Proxima Centauri was made by American astronomer Harold L. Alden in 1928, who confirmed the earlier results with a parallax of 0.783 ± 0.005″.

In 1951, American astronomer Harlow Shapley announced that Proxima Centauri is a flare star. Examination of past photographic records showed that the star displayed a measurable increase in magnitude on about 8% of the images, making it the most active flare star then known. The proximity of the star allows for detailed observation of its flare activity. In 1980, the Einstein Observatory produced a detailed X-ray energy curve of a stellar flare on Proxima Centauri. Further observations of flare activity were made with the EXOSAT and ROSAT satellites, and the X-ray emissions of smaller, solar-like flares were observed by the Japanese ASCA satellite in 1995. Proxima Centauri has since been the subject of study by most X-ray observatories, including XMM-Newton and Chandra.

Because of Proxima Centauri's southern declination, it can only be viewed south of latitude 27° N. Red dwarfs such as Proxima Centauri are far too faint to be seen with the naked eye; even from Alpha Centauri A or B, Proxima would only be seen as a fifth magnitude star. It has an apparent visual magnitude of 11, so a telescope with an aperture of at least 8 cm (3.1 in.) is needed to observe this star even under ideal viewing conditions—under clear, dark skies with Proxima Centauri well above the horizon.

Proxima Centauri is classified as a "late M-dwarf star", meaning that at M5.5 it falls to the low-mass extreme of M-type stars. This star's absolute visual magnitude, or its visual magnitude as viewed from a distance of 10 parsecs, is 15.5. When observed in the wavelengths of visible light the eye is most sensitive to, it is only 0.0056% as luminous as the Sun. More than 85% of its radiated power is at infrared wavelengths.

In 2002, optical interferometry with the Very Large Telescope (VLTI) found that the angular diameter of Proxima Centauri was 1.02 ± 0.08 milliarcsec. Because its distance is known, the actual diameter of Proxima Centauri can be calculated to be about 1.5 times that of Jupiter. The star's estimated mass is only 12.3% of a solar mass, or 129 Jupiter masses. Because of its low mass, the interior of the star is completely convective, causing energy to be transferred to the exterior by the physical movement of plasma rather than through radiative processes. This convection means that the helium ash left over from the thermonuclear fusion of hydrogen does not accumulate at the core, but is instead circulated throughout the star. Unlike the Sun, which will only burn through about 10% of its total hydrogen supply before leaving the main sequence, Proxima Centauri will consume nearly all of its fuel before the fusion of hydrogen comes to an end.

Convection is associated with the generation and persistence of a magnetic field. The magnetic energy from this field is released at the surface through stellar flares that briefly increase the overall luminosity of the star. These flares can grow as large as the star and reach temperatures measured as high as 27 million K—hot enough to radiate X-rays. Indeed, the quiescent X-ray luminosity of this star is roughly equal to that of the much larger Sun.

The chromosphere of this star is active, and its spectrum displays a strong emission line of singly ionized magnesium at a wavelength of 280 nm. About 88% of the surface of Proxima Centauri may be active, a percentage that is much higher than that of the Sun even at the peak of the solar cycle. Even during quiescent periods with few or no flares, this activity increases the corona temperature of Proxima Centauri to 3.5 million K, compared to the 2 million K of the Sun's corona. However, the overall activity level of this star is considered low compared to other M-class dwarfs, which is consistent with the star's estimated age of 4.85 × 10⁹ years, since the activity level of a red dwarf is expected to steadily wane over billions of years as its stellar rotation rate decreases. The activity level also appears to vary with a period of roughly 442 days, which is shorter than the solar cycle of 11 years.

Proxima Centauri has a relatively weak stellar wind, resulting in no more than 20% of the Sun's mass loss rate from the solar wind. Because the star is much smaller than the Sun, however, the mass loss per unit surface area from Proxima Centauri may be eight times that from the solar surface.

A red dwarf with the mass of Proxima Centauri will remain on the main sequence for about four trillion years. As the proportion of helium increases because of hydrogen fusion, the star will become smaller and hotter, gradually transforming from red to blue. Near the end of this period it will become significantly more luminous and warming up any orbiting bodies for a period of several billion years. Once the hydrogen fuel is exhausted, Proxima Centauri will then evolve into a white dwarf (without passing through the red giant phase) and steadily lose any remaining heat energy.

The TV documentary Alien Worlds hypothesized that a life-sustaining planet could exist in orbit around Proxima Centauri or other red dwarf stars. Such a planet would lie within the habitable zone of Proxima Centauri, about 0.023–0.054 AU from the star, and would have an orbital period of 3.6–14 days. A planet orbiting within this zone will experience tidal locking to the star, so that Proxima Centauri moves little in the planet's sky. Proxima Centauri's flare outbursts could erode the atmosphere of any planet in its habitable zone, but the documentary's scientists thought that this obstacle could be overcome. For example, if the planet had a strong magnetic field, the field would deflect the particles from the atmosphere. Searches for companions orbiting Proxima Centauri have been unsuccessful, ruling out the presence of brown dwarfs and supermassive planets. Precision radial velocity surveys have also ruled out the presence of super-Earths within the star's habitable zone. The detection of smaller objects will require the use of new instruments, such as the proposed James Webb Space Telescope. Proxima Centauri, along with Alpha Centauri A and B, is among the "Tier 1" target stars for NASA's proposed Space Interferometry Mission (SIM), which will theoretically be able to detect planets as small as three Earth-masses within two AU of a "Tier 1" target star.

Proxima Centauri has been suggested as a possible first destination for interstellar travel. Although the Voyager program spacecraft are anticipated to become the first spacecraft to enter interstellar space, they move relatively slowly, at about 17 km/s, requiring well over 10,000 years to travel each light-year. In comparison, Proxima is presently approaching at a rate of 21.7 km/s. However, it will only come as close as 3.11 light-years, and then move farther away after 26,700 years. Thus, a slow-moving probe would have only several tens of thousands of years to catch Proxima Centauri near its closest approach, and could end up watching it recede into the distance.>>

dougettinger wrote:
These facts do suggest that it is highly probable and not impossible that our Sun could have a companion red dwarf star, just like Centuari A, not yet discovered. Some astronomers have named such a hypothetical star as Nemesis. I am curious. What was its original predicted inclination to the ecliptic, orbital cycle and orbital diameter? Any elliptical parameters obviously would be selected to keep it in a rather stable orbit but also come close enough to perhaps affect the Sun's Oort Cloud.

http://en.wikipedia.org/wiki/Nemesis_%28star%29 wrote:
<<Nemesis is a hypothetical hard-to-see red dwarf star or brown dwarf, orbiting the Sun at a distance of about 50,000 to 100,000 AU (about 1-2 light-years), somewhat beyond the Oort cloud. This star was originally postulated to exist as part of a hypothesis to explain a perceived cycle of mass extinctions in the geological record, which seem to occur once every 27 million years or so.

In 1984, paleontologists David Raup and Jack Sepkoski published a paper claiming that they had identified a statistical periodicity in extinction rates over the last 250 million years using various forms of time series analysis. They focused on the extinction intensity of fossil families of marine vertebrates, invertebrates, and protozoans, identifying 12 extinction events over the time period in question. The average time interval between extinction events was determined as 26 million years. At the time, two of the identified extinction events (Cretaceous-Tertiary and Late Eocene) could be shown to coincide with large impact events. Raup and Sepkoski suggested that there might be a non-terrestrial connection.

Two teams of astronomers, Whitmire and Jackson, and Davis, Hut, and Muller, independently published similar hypotheses to explain Raup and Sepkoski's extinction periodicity in the same issue of the journal Nature. This hypothesis proposes that the Sun may have an as yet undetected companion star in a highly elliptical orbit that periodically disturbs comets in the Oort cloud, causing a large increase in the number of comets visiting the inner solar system with a consequential increase in impact events on Earth. This became known as the Nemesis (or, more colorfully, Death Star) hypothesis. Richard A. Muller suggests that the most likely object is a red dwarf with magnitude between 7 and 12, while Daniel P. Whitmire and Albert A. Jackson argue for a brown dwarf. If a red dwarf, it would undoubtedly already exist in star catalogs, but its true nature would only be detectable by measuring its parallax; due to orbiting the Sun it would have a very low proper motion and would escape detection by proper motion surveys that have found stars like the 9th magnitude Barnard's star.

The last major extinction event was about 5 million years ago, so Muller posits that Nemesis is likely 1 to 1.5 light years away at present, and even has ideas of what area of the sky it might be in (supported by Yarris, 1987), near Hydra, based on a hypothetical orbit derived from original apogees of a number of atypical long-period comets that describe an orbital arc meeting the specifications of Muller's hypothesis.

If Nemesis exists, then it may be detected by the planned Pan-STARRS or LSST astronomical surveys. In particular, if Nemesis is a red dwarf star or a brown dwarf, then the WISE mission (an infrared sky survey, currently underway, that will finish covering most of our solar neighborhood in movement-verifying parallax measurements by 2013) is expected to be able to find it, if it exists.>>

• The extremely distant planetoid Sedna has an extra-long and unusual elliptical orbit around the Sun, well beyond Pluto, ranging between 76 and 975 AU. Sedna’s orbit is estimated to last between 10.5 and 12 thousand years. Its discoverer, Mike Brown of Caltech, noted in a Discover magazine article that Sedna’s location doesn’t make sense: "Sedna shouldn't be there,” said Brown. “There's no way to put Sedna where it is. It never comes close enough to be affected by the Sun, but it never goes far enough away from the Sun to be affected by other stars.” Brown postulates that perhaps a massive unseen object is responsible for Sedna’s mystifying orbit, its gravitational influence keeping Sedna fixed in that far-distant portion of space.

Mike Brown's Planets wrote:
There is something out there
Posted: 20 Oct 2010 03:14 PM PDT
Is it real, or is it cat hair?

<<Seven years ago this week I was preparing one of my favorite lectures for The Formation and Evolution of Planetary Systems, a class I frequently teach at Caltech. “Preparing” is probably the wrong word here, because this lecture, called The Edge of the Solar System, was one I could give even if instantly wakened from a cold deep sleep and immediately put on stage with bright lights in my eyes and an audience of thousands and no coffee anywhere in sight. The lecture explored what was known about the edge of our main planetary system and the ragged belt of debris called the Kuiper belt that quickly faded to empty space not that much beyond Neptune. Conveniently, one of my most active areas of research at that time was trying to figure out precisely why this ragged belt of debris had such an edge to it and why there appeared to be nothing at all beyond that edge. I could wing it. So instead of preparing the lecture, I really spent that morning doing what I did whenever I had a few spare moments: staring at dozens of little postage-stamp cutouts of pictures of the sky that my telescope had taken the night before and my computer had flagged as potentially interesting. Interesting, to my computer, and to me, meant that in the middle of the postage stamp was something that was moving across the sky at the right rate to mark it as part of the Kuiper belt. I was not just lecturing about this debris at the edge of the solar system, I was looking for more of it, too.

I didn’t find more objects in the Kuiper belt every morning I looked, but that previous night seven years ago had been a good one. I quickly found two of the typical debris chunks moving slowly across the sky, and I was about ready to walk over to give my lecture, when, with only about a minute to spare, the outer solar system seemed to change before my eyes.

There, on my computer screen, was a faint object moving so slowly it could only have been something far more distant than what I was just going to walk into the classroom and declare to be the edge of the solar system. Maybe. The object was so faint that I didn’t know whether to believe it was real or not. If you look at enough sky – and, really, I had – you are bound to find some chance alignment of blips of noise or variable stars or cat hairs that looks just like something real.

I went into the classroom, delivered the lecture as I knew it, but stopped short at the end. “Here is the way I was going to end this lecture,” I told them.

I proceeded to talk about how nothing existed beyond the edge of the Kuiper belt (yes, yes, you sticklers, the Oort cloud is way out there, but that is not supposed to start up until 100 or 200 times further out than the edge of the Kuiper belt). “But I’m not sure I believe this anymore,” I said.

I told them about that morning’s blip. I couldn’t promise them that it was real, but I told them that if it was, the solar system might be very different place than I was just telling them. That little blip, far more distant than what was supposed to have been the edge of the solar system, was indeed real. It was Sedna. Sedna is the Inuit goddess of the sea, often depicted with the body of a seal, long hair, and no fingers.

A few weeks later, after confirming that Sedna was real and determining its unprecedentedly strange orbit around the sun, I came back, told the class all about it, and wrote down a few simple equations on the blackboard to show just how strange the orbit is and also the many different ways it might have gotten that way. “Come back and take my class again next year, and I’ll have it all figured out,” I confidently told them. That was seven years ago. Any poor student taking my advice would have sat through the last six years of lectures and still not learned what put Sedna where it is, since I still don’t know the answer.

The orbit of Sedna (red) set against the orbits of Jupiter (orange), Saturn (yellow), Uranus (green), Neptune (blue), and Pluto (purple)

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What makes Sedna’s orbit so strange? Sedna takes 12,000 years to go around the sun on its elongated orbit, and it never comes close to any of the planets.

Many objects out in the Kuiper belt have shockingly elongated orbits like Sedna. For almost all of these objects, this characteristic makes sense. These small leftover pieces of debris have been kicked around by planets throughout their existence. Whenever they come too close to one of the planets (usually Neptune, since it is the closest to these objects), they get a gravitational kick that can send them on a looping orbit to the distant outskirts of the solar system. But – and this is the key part here – unless they get kicked all the way out of the solar system, they always come back to where they were kicked. If you get kicked by Neptune, you can go zooming off into the unchartered regions far beyond the Kuiper belt, but you will come back to see Neptune again. When we look at the Kuiper belt, we see the results of all of this kicking clearly: the Kuiper belt objects that come closest to Neptune are on the most elongated orbits. Those far away are more free to go about their circular orbiting lives.

The exception to this rule is, of course, Sedna. Sedna has one of the most elongated orbits around, but it never comes anywhere close to Neptune or to any other planet. Indeed, the earth comes closer to Neptune than Sedna ever does. And the earth is not in danger of being kicked out of its orbit by Neptune anytime soon.

Something had to have kicked Sedna to have given it its crazy orbit. But what?

The answer is: something large that is no longer there, or that is there, but we don’t know about yet.

This answer is astounding. The orbit of every single other object in the entire solar system can be explained, at least in principle, by some interaction with the known planets (and, again, for you Oort cloud sticklers out there, the known galactic environment). Sedna alone requires Something Else Out There.

What is it? Seven years out, we still don’t know. The hypothesized culprits have included passing stars, hidden planets, Oort cloud brown dwarfs, and, of course, Sumerian-inspired alien conspiracy theories. Whatever it is, it is bound to answer profound questions about the origin and evolution of the solar system, as well as inspire many new questions we had never known to ask.>>

dougettinger wrote:Perhaps I do not know the scales of multiple star systems. Most observed binaries are within the orbit of Mercury or Venus. Would not a 15,000 AU separation rule out any significant gravitational attraction between two stars?

dougettinger wrote:So more facts come pouring into the Starship, Art. Thanks, again.

Proxima Centauri is 15,000 AUs distant (.21 ly) and takes about 500,000 years to orbit.

Sedna is 76 to 975 AUs and takes 10,000 to 12,000 years to orbit. The orbit is admittedly very elliptically elongated.

Hypothetical Nemesis is 50,000 to 100,000 AUs (1 to 2 ly) away and takes about 27 million years thereby matching certain known periods of extinction.

I am really interested in knowing more about orbital mechanics and solar system formation.

Chris Peterson wrote:

dougettinger wrote:Perhaps I do not know the scales of multiple star systems. Most observed binaries are within the orbit of Mercury or Venus. Would not a 15,000 AU separation rule out any significant gravitational attraction between two stars?

The vast majority of double star systems have stellar separations of many astronomical units, not less than one.

There is no limit on how far apart two bodies can be and still be in orbit around each other. The farther apart they get, the lower their relative escape velocities with respect to one another, meaning they could easily be perturbed into hyperbolic (open) orbits. But in a low density part of space, such as where we are, 15,000 AU is not too far for a sustainable multiple star system.

neufer wrote:

dougettinger wrote:So more facts come pouring into the Starship, Art. Thanks, again.

Proxima Centauri is 15,000 AUs distant (.21 ly) and takes about 500,000 years to orbit.

Sedna is 76 to 975 AUs and takes 10,000 to 12,000 years to orbit. The orbit is admittedly very elliptically elongated.

Hypothetical Nemesis is 50,000 to 100,000 AUs (1 to 2 ly) away and takes about 27 million years thereby matching certain known periods of extinction.

I am really interested in knowing more about orbital mechanics and solar system formation.

Sedna's semi major axis is (76 + 975)/2 = 525 AU

Kepler's 3rd law tells us that Sedna's period should be 525^3/2 ~ 12,000 years.

"Nemesis's period" is 27 million years so it's semi major axis is 27,000,000^2/3 = 90,000 AU (1.26 ly)

dougettinger wrote:I have a spectroscopic binary catalog (1992) that shows all the sampling under 1/2 AU. How are the vast majority of binaries over one AU apart currently detected? By parallax ? By wobble ?

Since Neptune is on a very weak tether with the Sun at about 40 AUs. And Neptune has supposely been around since close to the beginning of the solar system, then we can safely assume that the Sun's trips around the galaxy have all been luckily in a low density part of space(?) That is rather amazing.

dougettinger wrote:
Continuing with your simple equations, Sitchin's proposed 10th planet could possibly have the following parameters:
(3600 years)2/3 = 235 AUs and a possible elliptical orbit could be 60 to 400 AUs. Is this assessment correct ?

dougettinger wrote:So what unusual perturbation(s) could have possibly caused the elongated orbit of Sedna, the highly elliptical and inclined orbit of Pluto, and the highly inclined and longer period asteroids and comets ?

Mike Brown's Planets wrote:
There is something out there -- part 2
Posted: 28 Oct 2010 11:27 AM PDT
The view from Sedna

<<Seven years ago, the moment I first calculated the odd orbit of Sedna and realized it never came anywhere close to any of the planets, it instantly became clear that we astronomers had been missing something all along. Either something large once passed through the outer parts of our solar system and is now long gone, or something large still lurks in a distant corner out there and we haven’t found it yet.

Of all of the planets, comets, asteroids, and Kuiper belt objects in the solar system, Sedna is the only one that tells us this astounding fact so glaringly. The orbit of every single other object in the entire solar system can be explained, at least in principle, by some interaction with the known planets. Sedna alone requires something else out there.

But what?

In our 2004 paper announcing the discovery of Sedna (give it a try; though it – like all research papers – has some technical details that might not make sense, I believe it to be relatively readable), we suggested three possibilities. Our first idea was that perhaps there was an unknown approximately earth-sized planet circling the sun about twice the distance of Neptune. Sedna could have gotten too close to this Planet X and been given a kick which would have flung it out into a far corner of our solar system. But, like always, nothing can kick you into a far corner and make you stay there. You always come back to the spot where you were kicked. So Sedna’s new orbit would be one that came in as close as this Planet X and went far into the outer solar system – just like Sedna’s orbit. Back in 2003 I had liked this idea a lot. Our search of the skies had only begun a few years earlier, so the prospect that there might be an earth-sized planet awaiting discovery seemed pretty exciting indeed. It was, admittedly, a long shot, but discovering planets always is.

The second possibility that we considered and wrote about was that perhaps a star had passed extremely close to our solar system at some point during the lifetime of the sun. “Extremely close” for a star means something like 20 times beyond the orbit of Neptune, but that is 500 times closer than the current nearest star. A star passing by that close would have been brighter than the full moon and would have been the brightest thing in the night sky for hundreds of years. Perhaps our early ancestors even temporarily lived under a dual-star sky. Sedna, before the rogue star came calling, would have been a normal Kuiper belt object with a looping orbit which would take it out to the distant solar system but then eventually back to Neptune (which had, presumably kicked it around earlier). But on one of its trips to the edge of the solar system, Sedna would have accidentally gotten too close to this interloping star, and the star would have given Sedna another little kick. Suddenly, Sedna would find itself on a new orbit which no longer went back to Neptune. The orbit would, of course, have to go back to the spot where Sedna had gotten the kick from the passing star, but the star would be long gone by then. This idea was a fun one, and, best of all, we could do a reasonably good job estimating the probability that something like this might have occurred. Looking at the number of star near us in the galaxy and fast they all move relative to each other, we found that the chances of such a rogue star encounter happening sometime in the past 4.5 billion years was around 1%. Not good odds to hang your theory on. (People often ask: can’t you just go back and find the star that did it and see if it is there? Sadly, there is no chance. The sun is 4.5 billion years old and it takes about 250 million years to orbit around the galaxy, so it’s gone around about 18 times. So has everything else in the vicinity. Everything is now so mixed up that there is no way to know for sure what was where back when.)

The third possibility was the one that we deemed the most likely. Instead of getting one big kick from an improbably passing star, imagine that Sedna got a lot of really small kicks from many stars passing by not quite as closely. The chances of this happening might seem low, too, but astronomers have long known that most stars are born not alone, but in a litter of many stars packed together. How tightly? In our region of the galaxy, there is currently something like one star per cubic parsec (don’t worry too much about these units here; suffice it to say that a parsec is a little less than the distance to the nearest star, so it is not surprising that in a box with edges about that length there is about one star). In the cluster of stars in which the sun might have been born there would have been thousands or even tens to hundreds of thousands of stars in this same volume, all held together by the gravitational pull of the massive amounts of gas between the still-forming stars. I firmly believe that the view from the inside of one of these clusters must be one of the most awesome sights in the universe, but I suspect no life form has ever seen it, because it is so short-lived that there might not even be time to make solid planets, much less evolve life. For as the still-forming stars finally pull in enough of the gas to become massive enough to ignite their nuclear-fusion-powered cores they quickly blow the remaining gas holding everything together away and then drift off solitary into interstellar space. Today we have no way of ever finding our solar siblings again. And, while we see these processes occurring out in space as other stars are being born, we really have no way to see back 4.5 billion years ago and see this happening as the sun itself formed.

Until now.

Maybe.

If Sedna got put on its peculiar orbit by the interactions of all of these stars 4.5 billion years ago, it is now a fossil record of what happened at the time of the very birth of sun. Everything else in the solar system has been kicked and jostled and nudged by planets big and small so there is no way to trace them back 4.5 billion years. Sedna, on the other hand, has been doing nothing but going around and around the sun in its peculiar elongated orbit every 12,000 years. After almost half a million of those orbits, Sedna remains lonely and untouched by anything else. By watching the orbit of Sedna we could be watching 4.5 billion years in the past.

All of these possibilities are exciting! A new planet! A rogue star! Fossils from the birth of the sun! And in the years since Sedna’s discovery other astronomers have chimed in with their own ideas, including the possibility that Sedna was kicked by something large out in the Oort cloud (small planet? Brown dwarf? Nemisis? Who knows) and, in the most imaginative spin, that Sedna was kicked by the sun. The sun? Yes, because, in this hypothesis, Sedna used to orbit a different star, and the sun got close and kicked Sedna around and stripped if away. Sedna would then be the first known extra-solar dwarf planet. Or something like that.

Sedna is telling us something profound, but what? With only a single object, there is absolutely no way to know. It would be like finding a fossilized skeleton of a T. Rex and trying to infer the history of the dinosaurs. If you had just that one skeleton you would know just what to do: head back out into the desert and start digging. When we found Sedna, we, too, knew what was next: head back out into the night and keep looking. Until we found more, we wouldn’t know what this profound bit of the solar system was trying to scream so loudly in our ears.>>

Ann wrote:
About a year ago I debated with a stark raving mad Swede who insisted that Niburu was not only on its way, but that it was already visible in the sky - indeed, it was not only visible, but it was the brightest object in the night sky... If I just went outside and looked at the sky, I couldn't fail to see it. And if somehow I still couldn't spot it, I could just come over to him and he would point it out to me. So would I please send him some money now, so that he could start building his Niburu-proof shelter?

I told him that if he would inform me, over the internet, where in the sky I could see Niburu, then I would go to my astronomy club and observe it with our 14 inch telescope. If Niburu looked real enough through our telescope, I would consider sending him money.

http://en.wikipedia.org/wiki/Bart%27s_Comet wrote:
<<In "Bart's Comet", Bart Simpson accidentally discovers a comet, which is heading towards Springfield. The show's writing staff saw an issue of Time magazine which presented the threat of comets hitting Earth on its cover, and decided to create an episode in a similar vein.
---------------------------------------------
After Bart sabotages Principal Skinner's weather balloon, Skinner decides to punish him by having him help with his amateur astronomy. Skinner dreams of finding something in the sky and having it named after him.

• ............................................
  Bart: [about comets] Who names these things anyway?
  
  Principal Skinner: Whoever discovers them. I've been hoping I could find something that would be named after me.
  
  Bart: And you've never found anything?
  
  Principal Skinner: Once... but by the time I got to the phone, my discovery had already been reported by Principal Kohoutek...
  [a cloud covers the moon; ominous music plays] I got back at him, though... him and that little *boy* of his.
  [cloud passes; music ends]
  ............................................

Bart accidentally locates a comet which is named after him. Scientists soon discover that the comet is heading straight for Springfield. Professor Frink plans to launch a missile at the comet, dispelling everyone's fears. However, the missile flies past the comet, instead blowing up the only bridge out of town, dooming the people. After a Congressional bill to evacuate Springfield is defeated, Homer decides that they should stay in the bomb shelter that Ned Flanders built. Anticipating this, Ned had built it large enough for both families. One hour before Springfield is destroyed, the rest of the townspeople arrive, demanding a place in the bunker. Homer is unable to close the door and someone has to leave. Homer decides that the only thing the "world of the future" will not need is left-handed stores and tells Ned to go. Eventually, Homer feels guilty and leaves as well, followed by the other townspeople and they all converge on a hill to await death. As the comet enters the atmosphere, it burns up in the thick layer of pollution over Springfield, popping Skinner's weather balloon and destroying Ned's bunker on the way. The town decides to burn down the observatory to prevent a similar incident from ever happening again. The Simpsons, however, are more worried at the fact Homer correctly predicted the fate of the comet - that it would burn up and fall to earth as a rock smaller than a Chihuahua's head.

• Bart: What's really amazing is this is exactly what Dad said would happen!
  
  Lisa: Yeah, Dad was right!
  
  Homer: I know, kids, I'm scared too! >>