Reactor Coolants.

As Lead-Bismuth Eutectic or LBE is a eutectic alloy of lead (44.5%) and Bismuth (5 % Lead-Bismuth (55.5%)) It maybe used as a coolant in some nuclear reactors and is a proposed coolant. As it appears wise to accelerate the development of fast reactors. With the efficient reprocessing fuel technology. Here with some of these papers, as coolants are made secure its been proposed as inefficient technologies become hazardous and dated. These components are based on two types of small fast reactors, on and off systems. If you like non hazards safety these are here been discussed – the sodium-cooled fast reactor, which has already been built and can be further improved. The lead-cooled fast reactor that could be developed relatively soon. An accelerated development of the latter is possible due to the sizeable experience on lead-bismuth alloy coolant, as in some alpha-class submarine reactors. With the research efforts on accelerator driven systems in the EU and other countries. As a preference something that remains a fluid that doesn't boil on impact? Some forms of silica are in use with a new range of subatomic particles. Also some coolant maybe applicable for small casings such as in heat ex changers, these can be use as inherent gas, for example helium or ‘radon’ maybe a better alternative, here with an open discussion at a later date.

The first, comparative calculations on critical masses, fissile enrichment's, and burn-up swings of mid-sized SFRs and LFRs (600 MWe) are presented. Monte Carlo transport and burn-up codes were used in the analyses. Moreover, local Doppler, coolant temperature and axial fuel expansion reactivity coefficients were also evaluated with MCNP and subsequently used in the European Accident Code-2 to calculate reactivity transients and unprotected Loss-of flow accidents (ULOF). Further, unprotected Loss-of-Flow as well as decay heat removal (total Loss-of-Power, TLOP) were calculated with STAR-CD CFD code for both systems. The tight pin lattice SFRs (P/D=1.2) showed to have a better neutron economy than wide channel LFRs (P/D=1.8), resulting in larger BOL actinides inventories and lower burn-up swings for LFR. The reactivity burn-up swing of LFR self breeder could be limited to 3$ in 3 years. 

The calculations revealed that LFRs have an advantage over SFRs in coping with the investigated severe accident initiators (ULOF, TLOP). The reason is better natural circulation behaviour of LFR system and much higher boiling temperature of lead. An unprotected Loss-of flow accident in LFR leads to only a 250 K coolant outlet temperature increase whereas in SFR coolant would boil. Regarding the economics, the LFR seems to have an advantage since it does not require an intermediate coolant circuit. However, it was also proposed to avoid an intermediate coolant circuit in an SFR by using a super critical CO2 Brayton cycle.

Sodium has superior thermal hydraulic properties, allowing for tight pin lattices. There is a large (but not always positive) experience with operation of sodium-cooled fast reactors. While several power reactors have been shut down, BOR-60, JOYO, Phénix, and BN-600 are still operating, the latter being in quasi-commercial operation since 1982. New sodium-cooled reactors are under construction in Russia, China and India. Sodium features a reasonably low melting temperature, but also a low boiling point (1156 K), which raises safety concerns regarding unprotected transients leading to a coolant heat up. Sodium exhibits high chemical activity with water, water vapour and air - a limited sodium leak and fire has stopped the operation of the Japanese MONJU reactor since 1995. 

The choice of lead and lead-alloys as coolants is motivated on the one hand by their high boiling temperatures, which avoids the risk of coolant boiling. On the other hand, lead and lead-alloys are compatible with air, steam, CO2, and water, and, thus, no intermediate coolant loop is needed as in the sodium-cooled system. Lead-bismuth eutectic provides a low melting point (398 K) limiting problems with freezing in the system and features a low chemical activity with water and air excluding the possibility for fire or explosions. A drawback connected with lead/bismuth 'is the accumulated radioactivity in lead/bismuth' (mainly due to the α-emitter 210Po, T1/2 = 138 days), which could pose difficulties during fuel reloading or repair work on the primary circuit. However, IPPE Obninsk staff has developed methods to cope with the polonium during refuelling and maintenance.

Lead is considered as a more attractive coolant option than lead/bismuth mainly due to its higher availability, lower price and lower amount of induced polonium activity (by a factor of 104 ), as given in a publication about BREST- 300 LFR reactor design (Adamov, 2001). Pure lead has a melting temperature of 601 K, which narrows in the reactor’s operational interval to about 680-870 K. However, after more research, higher outlet temperatures will eventually be possible. Redundant electrical heaters are proposed to be introduced in order to avoid problems with freezing and blockages in fresh cores. Lead-alloy coolant velocities are limited by erosion concerns of protective oxide layers to about 2.5-3 m/s (Novikova, 1999). 

Typical sodium velocities are up to 10 m/s, hence lead has, in practise, a lower heat removal capacity, which require higher pin pitch-to-diameter ratios to stay below cladding temperature limits. However, as shown later in this paper these high pitch-to-diameter ratios enhance the natural circulation capability of the coolant, and thus, the safety performance of LFRs. Corrosion resistance of the structural material can be achieved through controlling oxygen content in lead or lead-alloy. This technology has been used in the alpha class submarines and its effectiveness up to 820 K has been confirmed by the EU ADS research. The surface alloying by the so-called GESA method enhances corrosion resistance of the structural material further, at least up to 870 K (Wider, 2003). It should also be noted that pure lead shows to be less corrosive than lead/bismuth eutectic at the same temperature (Wider, 2003). Fast creep of the reactor vessel during coolant heat-up transients is another important issue to be considered. It occurs significantly below the lead boiling point, ∼1170 K for SS- 316, 1250 K for NIMONIC alloys and possibly higher for ODS steels. These values refer to an 11 m tall vessel. although this reactor appears very safe the sump has its limitations. 

Neutronically, the lead and lead/bismuth energy loss due to the elastic scattering is significantly smaller than that for sodium. However, due to the presence of several thresholds for inelastic scattering in the energy interval from 0.57 to 2 MeV, the neutron energy loss in inelastic scattering is notably larger than for sodium. Therefore, the neutron spectrum of lead and lead/bismuth cooled reactors will be decreased for energies above 1 MeV. On the other hand, the magnitude of the neutron flux for sodium-cooled reactor is decreased in the energy interval of 0.7-1.5 MeV, where contributions to the neutron slowing down from elastic and inelastic scattering reactions are nearly equal. Additionally, the neutron mean free path in sodium is larger than that of lead or lead/bismuth. 

Therefore, the leakage of neutrons and their contribution to overall neutron balance in the system is more significant for sodium. Further, higher scattering in lead and lead/bismuth without increasing the moderation for neutrons below 0.5 MeV prevents the neutrons from escaping from the internal parts of the lead-alloy cooled cores and, at the same time, provide an excellent reflecting capability for the neutrons, which escape the core. Hence, we can also infer that the neutron economy of the lead-alloy cooled systems would be better than for sodium-cooled counterparts having the same geometry. E.g., lead-alloy cooled, (U,Pu)O2 fuelled systems require smaller plutonium enrichments than sodium counterparts to reach critical.

Hybridisation.

Hybridisation and its theory of 1931 as the bonds valence to the bond theory occures. This is the concept that happens when mixing atomic orbitals, as into the new hybrid orbitals (with different energies, shapes, etc. have the component atomic orbitals) Now suitable for the pairing of electrons to form chemical bonds within the valence bond theory. Hybrid orbitals are very useful in the explanation of molecular geometry and atomic bonding as properties. Although sometimes taught together with the valence shell, electron-pair repulsion. The (VSEPR) theory, valence bond and hybridisation are in fact not related to the 'valence shell electron pair repulsion theory known as the VSEPR model. 

Chemist Linus Pauling first developed the hybridisation theory in 1931 in order to explain the structure of simple molecules such as methane (CH 4 ) using atomic orbitals. Pauling pointed out that a carbon atom forms four bonds by using one s and three p orbitals, so that "it might be inferred" that a carbon atom would form three bonds at right angles (using p orbitals) and a fourth weaker bond using the s orbital in some arbitrary direction. In reality however, methane has four bonds of equivalent strength separated by the tetrahedral bond angle of 109.5°.

Pauling explained this by supposing that in the presence of four hydrogen atoms, the s and p orbitals form four equivalent. hybridisation, this approximation is based on atomic orbitals, similar to those obtained for the hydrogen atom, the only neutral atom for which the Schrödinger equation can be solved exactly. In heavier atoms, such as carbon, nitrogen, and oxygen, the atomic orbitals used are the 2s and 2p orbitals, similar to excited state orbitals for hydrogen. Quantum state of a quantum system changes with time. It was formulated in late 1925, and published in 1926, by the Austrian physicist Erwin Schrödinger. 

In classical mechanics Newton's second law, (F = ma), is used to mathematically predict what a given system will do at any time after a known initial condition. In quantum mechanics, the analogue of Newton's law is Schrödinger's equation for a quantum system (usually atoms, molecules, and subatomic particles whether free, bound, or localized). Schrödinger equation for a harmonic oscillator. Is when the wave function. Leads to the probability distribution of finding the particle with this wave function at a given position. Examples of stationary states, which correspond to standing waves.

The most famous example is the non-relativistic Schrödinger equation for a single particle moving in an electric field (but not a magnetic field; need to see the Pauli equation) interaction of the particle's spin with an external electromagnetic field. It is the non-relativistic limit of the Dirac equation and can be used where particles are moving at speeds much less than the speed of light, so that relativistic effects can be neglected. It was formulated by Wolfgang Pauli in 1927. Two-component spinor, therefore, we can see that the spin of the particle only affects its motion in the presence of a magnetic field.

These are most lightly to be involved in a chemical reaction than in solids, electrons are the primary means of conducting current. (since protons are larger, they are typically bound to a nucleus and thus more difficult to move). In liquids, current carriers are more often ions. The possibility of electrons was predicted by Richard Laming (1838-1851), Irish physicist G. Johnstone Stoney (1874), and other scientists. The term "electron" was first suggested by Stoney in 1891, although the electron was not discovered until 1897, by British physicist J.J. Thomson.

Wolf 1061c Earth

Wolf 1061c the closest planet yet a large water planet that could support life.
As its beyond our solar system, it would be a risky venture. Then have a re-entry and have a never return card. As for decades we could see only stars and a few nearby planets from our own solar system. As when we looked to the heavens. Twenty years ago we started spotting exo-planets; then potentially habitable exoplanets; and now astronomers have pinpointed the closest exoplanet yet that might support life. The so-called "super-earth" is one of three planets orbiting a red dwarf star called Wolf 1061 that's just 14 light-years away. "While a few other planets have been found that orbit stars closer to us than Wolf 1061, those planets are not considered to be remotely habitable," said Duncan Wright, of the University of New South Wales in Australia. Wright is lead author of a study on the discovery that will be published in The Astrophysical Journal Letters.

Wright says it's the middle planet, called Wolf 1061c, that orbits in the habitable "Goldilocks zone" of the star, where temperatures are not too hot and not too cold but just right for liquid water, making life as we know it theoretically possible. "It is fascinating to look out at the vastness of space and think a star so very close to us  a near neighbour could host a habitable planet," Wright says. "Near" is of course a very relative term. Current understanding of physical limitations mean it would take at least 14 years to make the journey to Wolf 1061c, and we would have to invent light-speed travel first. Still, this planet is a much closer neighbor than most other potentially habitable exoplanets spotted so far, which tend to be hundreds or thousands of light-years away. One notable exception is Gliese 667 Cc, which sits 22 light-years away. If future generations did make it to Wolf 1061c, they'd find an oversize rocky planet circling a star that's dimmer and smaller than our sun.

The UNSW team says it hopes to study the atmosphere of the planet in the future to see if it might be conducive to life. It could also make an excellent candidate for observation by the next generation of powerful telescopes, starting with the Transiting Exoplanet Survey Satellite (TESS) and the James Webb Space Telescope, both set to launch in the next two to three years. Of course, by that time the math makes it seem likely that we'll have found a number of potentially habitable planets that are even closer still. Could a 'super-Earth' be even more habitable than our own planet? There's reason to believe that other planets might be better for supporting life as we know it, and they might not even be that far off, cosmically speaking.Could the redder planet be the better planet? Rene Heller It's popular to talk about how wonderful, beautiful and rare a treasure our planet is; I certainly say such things all the time, and many satellite, as photos testify to this truism. But let's be real for a minute, my fellow humans and A.I. beings we don't really have first-hand experience with an adequate sample size of habitable planets to say this for sure as Russian Photo Is Released. 

In fact, a pair of scientists have been looking into the possibility that there might be a distant planet (or a couple of them or maybe 3 billion) out there more suitable to supporting life as we know it. They even describe what such a "super-habitable" planet might look like a super-Earth with a mass double or triple that of our planet, orbiting in the habitable zone around a K-type dwarf star several billion years older than our sun. The basic explanation for why such a planet would make a "better Earth" is that it might have a long-lasting magnetic field, which protects the planet from the abundant radiation of space and stars, and plate tectonics activity, which keeps some of the key life-supporting elements in balance. Also, a planet with double or triple the mass of Earth would mean more surface gravity, likely forming more shallow lakes and oceans, more archipelago-like land masses and fewer deserts. More shallow waters might mean more biodiversity, as they typically do here on our planet?

The 7 confirmed exoplanets most likely to host life (pictures) In other words, a better Earth would be a little more than a "Water World" and a lot less of a film planet as in "Mad Max." It would also be awesome for snorkelling. That's part of the case that René Heller of McMaster University in Ontario and John Armstrong from Weber State University in Utah plan to make at the 2015 Astrobiology Science Conference in Chicago in June, according to an advance briefing on the session. The duo admit that they are refuting the "Rare Earth Hypothesis", which basically posits that the emergence of life on Earth was a result of amazing coincidences and everything being in the right place at the right time just once off in the milky way galaxy. "While we agree that the occurrence of another truly Earth-like planet is trivially impossible, we hold that this argument does not constrain the emergence of other inhabited planets," Heller and Armstrong write these have to have an atmosphere otherwise wouldn't survive as a specie.

In other words, keep your "Star Trek" dreams alive and always remember the Prime Directive, as it could come in handy in a distant future because humanity carbon dioxide could make for a whole oil deposit.
Especially if a superhabitable planet is discovered in orbit around Alpha Centauri B. This is one of the nearest stars to our solar system, at just "four light-years away". This next door neighbor, cosmically speaking, fits the requirements set by Heller and Armstrong for fostering possible super-snorkeling worlds as described above. Astronomers have already found one Earth-size planet in orbit around this star, but it is not in the habitable zone. However, there's no reason to believe that there isn't a super-Earth lurking a little farther away from Alpha Centauri B yet to be detected. For now, until we build our first warp drive or send out our first multi-generational ship of colonists to Alpha Centauri B, we'll just have to deal with the planet we've got, where frankly, even the deserts and the deep oceans are still pretty awesome and still full well wishers.

Fields of Force.

As The Meissner effect is an expulsion of a magnetic field from a superconductor during its transition to the superconducting state.
The German physicists Walther Meissner and Robert Ochsenfeld discovered the phenomenon in 1933 by measuring the magnetic field distribution outside superconducting tin and lead samples. The samples, in the presence of an applied magnetic field, were cooled below their superconducting transition temperature. Below the transition temperature the samples cancelled nearly all interior magnetic fields. They detected this effect only indirectly; because the magnetic flux is conserved by a superconductor, when the interior field decreased, the exterior field increased. The experiment demonstrated for the first time that superconductors were more than just perfect conductors and provided a uniquely defining property of the superconducting state.

The Casimir effect is a small attractive force that acts between two close parallel uncharged conducting plates.
It is due to quantum vacuum fluctuations of the electromagnetic field. The effect was predicted by the Dutch physicist Hendrick Casimir in 1948. According to the quantum theory, the vacuum contains virtual particles which are in a continuous state of fluctuation. Casimir realised that between two plates, only those virtual photons whose wavelengths fit a whole number of times into the gap should be counted when calculating the vacuum energy. The energy density decreases as the plates are moved closer, which implies that there is a small force drawing them together. Plasma actuators are a type of actuator currently being developed for aerodynamic flow control. Plasma actuators impart force in a similar way to ionocraft.

A dielectric-barrier-discharge (DBD) plasma is used to induce a flow close to a surface for flow control. The DBD plasma actuator consists of two electrodes separated by a dielectric barrier. When a high voltage alternating current is applied, the air close to the exposed electrode is ionized. On the surface the ions collide with the surrounding neutral air particles so as to transfer their momentum to the air. Therefore, the plasma actuator can be thought of as imposing a localized body force to the surrounding air. The aim of using this electric wind is in most cases to accelerate the airflow tangentially and very close to the actuator's surface in order to modify the local airflow profile. The main advantage of this process is that it directly converts electric energy into kinetic energy without involving moving mechanical parts.

Star Classifications.

Geometric physics and Astronomy. Star classification (Stellar classification) In physics, stars are classified by their surface temperature, that is associated to specific spectral patterns.
An early schema from the 19th century ranked stars from A to P, which is the origin of the currently used spectral classes. After several transformations, today the spectral classification includes 7 main types: O, B, A, F, G, K, M. A popular mnemonic for remembering this order is "Oh, Be A Fine Girl, Kiss Me". This is called "Morgan-Keenan spectral classification", even though its form was already by Annie Cannon, also based on the work of other astronomers from the Harvard College Observatory. The classes, listed from hottest to coldest, are their class and temperature

O 30,000 - 60,000 °K B 10,000 - 30,000 °K A 7,500 - 10,000 °K F 6,000 - 7,500 °K G 5,000 - 6,000 °K K 3,500 - 5,000 °K M 2,000 - 3,500 °K As one will notice that hottest stars are blue, while coldest stars are red. This seems unusual to most people, who associate red with hot and blue with cold. This is because we see fire as yellow, orange or red, but light produced by hotter sources is blue. However, blue sources are hard to find on Earth because it requires a large amount of energy. Also notice that this is true for light-emitting objects. However, the color of a common object, like a blue shirt or a piece of red paper, is not related to its temperature. Confusion also arises when one considers how artists or photographers may refer to the color of light: usually they describe reds as "warm" colors and blues as "cool".

Kelvin Temperature the K means Kelvin degrees, that can be calculated adding 273 to Celsius degrees. Here are 4 examples of common temperatures in Fahrenheit, Celsius and Kelvin degrees. O F Condition Water boils 212 Room Temperature Water Freezes Absolute Zero -460 However, a star temperatures are much higher, so the following table can be useful: Conditions in different temperatures Kelvins Celsius 1,808 °K 1,535 °C Melting point of iron Boiling point of lead 1,740 °C 2,013 °K 3,683 °K 3,410 °C Melting point of tungsten 3,925 °K 3,652 °C Sublimation point of carbon 5,780 °K 5,500 °C Surface temperature of the Sun

Boiling point of tungsten 5,555 °C 5,828 °K Spectral types the seven spectral classes were subdivided into tenths (for example B0, B1, B2, B3, ..., B9, A0, A1, A2, A3, ... A9, F0, F1, F2, F3...). The Sun is a G2 star. Class O stars are very hot and luminous, being blue in colour. Naos (in the constellation Puppis) shines with a power close to a million times solar. These stars have prominent ionized and neutral helium lines and only weak hydrogen lines. Class O stars emit most of their radiation in ultra-violet. Class B stars are again very luminous, Rigel (in the great constellation Orion) is a prominent B class blue supergiant. Their spectra have neutral helium and moderate hydrogen lines. As O and B stars are so powerful, they live for a very short time. They do not stray far from the area in which they were formed as they don't have the time. They therefore appear clustered together in the OB associations, which are associated with giant molecular clouds. The Orion OB association is an entire spiral arm of our Galaxy. 

Class A stars are amongst the more common naked eye stars. Deneb in Cygnus is another very powerful star. Sirius, that appears the brightest star as seen from Earth, is also an A class star, but not nearly as powerful. As with all class A stars, they are white. Many white dwarfs are also A. They have strong hydrogen lines and also ionized metals. Class F stars are still quite powerful and they are average-sized, such as Fomalhaut in Pisces Australis. Their spectra is characterized by the weaker hydrogen lines and ionized metals, their colour is white with a slight tinge of yellow. Class G stars are probably the most well known for the reason that our Sun is of this class. They have even weaker hydrogen lines than F but along with the ionized metals, they have neutral metals. Class K are orange stars which are slightly cooler than our Sun. Some K stars are giants and supergiants, such as Arcturus, while others like Alpha Centauri B are smaller. They have extremely weak hydrogen lines, if they are present at all, and mostly neutral metals. Class M is the most common class by the number of stars. All red dwarfs, such Proxima Centauri, the closest star to our Solar Sysem, go in here, and they are plentiful. M is also host to most giants and some supergiants such as Antares in Scorpio and Betelgeuse in Orion, as well as Mira variable stars. These red giants are old stars. The spectrum of an M star shows lines belonging to molecules and neutral metals but hydrogen is usually absent. Titanium oxide can be strong in M stars.

M stars may be dwarf stars or supergiant stars and A stars can be white dwarfs or white giants as well. However, not all combinations are possible.

For example, F and G stars must be average-sized stars.This can be understood through the Hertzsprung-Russell diagram, that is very important in astrophysics and relates temperature and spectral classification of stars with their luminosity and size.While these descriptions of stellar colors are traditional in astronomy, they really describe the light as we see them from Earth, after it has been scattered by the atmosphere. The Sun is not in fact a yellow star, but has the color temperature of a body of 5780 K, that is a white with no trace of yellow which is sometimes used as a definition for standard white. Spectral type additions. Ad number of other spectral types have been taken into use for rare types of stars, these are W, L, T, S, and C (that includes R and N).

Huygens Titans Geometric.

Titan probe landed in January 2005. Scientists have been modelling the interior. Explaining the evolution of Titan Saturn's moon an describing it in attempt to match both.

As the moments of inertia and the study of tidal currents as it has since been a decade since Huygens probe by ESA that landed on Saturn's moon Titan. Huygens probe it’s at the northern most seabed as it is gentler and smoother surface than the southern. This is a land scape with flooded valleys and punctuated by steep peaks. Getting the depth profile meant that scientists could estimate how much liquid hydrocarbon.

As it rests in Ligeia Mare: As much as 100 times more than the oil and gas reserves on Earth combined which was organic. As peering into the depth of Kraken Mare, which this would cover an area of at least 400,000 square kilometers across, or approximately equal to the size of Germany.

“Kraken appears to consist of no fewer than three distinct basins, each about the size of Ligeia Mare,” Lunine says.
“So there’s a lot of sea to see on Titan.” Phenomena is a gathering of spirited science writers who take delight in the new worlds. As the strange, the beautiful and awe-inspiring details of our world. Nadia Drake is a science and a journalist who grew up thinking about cosmic questions and staring at Saturn through giant telescopes. This is her space talk about space from other worlds to exploding stars to the fabric of the universe. Her work has also appeared in Science News, Nature, New Scientist, the Proceedings of the National Academy of Sciences, and geometricphyics She lives in beautiful, San Francisco. Also Follow On Twitter Titans Revealed @natgeoscience.

Earth Magnetic Field.

Nibiru, Sirius and the Sun, are deemed to be stars. They are relatively unknown, these have a polar plane. As does Earth it has a magnetic plane rises or falls to this galactic medium and this fluctuates. One has to ponder a thought to some of these new findings. Find the ancient structures point to this, so does the importance of which the alignment of these structures thus formed for example the pyramids. This seems to have been a world wide project of such significance by there importance and being built with only one reason. As this points towards the Earths magnetic flip.
It seems to have been a project to control Earth's energetic resonance via the use of directional wavelengths. This is done true their tip to align energy. Maybe this was to stabilise the moons orbit aligning it to the Earth's Core? It was later said they were built as a high priest alter of worship for mummification. So as to get their plan correct, these were to become a world wide network of pyramids extending the globe to focal points. With Bosnian as many other locations in reach thus concluded. Some just put this age of pyramid building down, to be an enclosure for learning. Where the organisation of labour took place, like the internet today and this may make for a fantastic computer game. If this was done so the outer edge to the sun polar flip wouldn't flux, as it approached near the suns equatorial top and bottom axis. This would be a huge project that wouldn't be repeated? If it's all this is speculation, even the carvings claim that there are 10 planets with one exo planet depicted having an orbit of 39 light years, Then Earth may be the final planet in its quest for survival in our system, as it becomes the contest for zombie domination, as gravity vectors conclude and onto our reduced cranium? Here is a big forget, that some apes show more intellect, under gravitational G force than us as a species. Such is this to human civilisation, as it becomes quite a large constraint also.
MRI have shown no offence a decline in human cognitive activity due to inactivity. Earth last humanoid might not be so far into the distance future, that been said what animal will dominate the Earth. As a planet. As Venus and Mars are now out of the way this does leave the? Here is example of all the detections that have been made since the nineteenth century. Some of the earliest involve the binary star 70 Ophiuchi.
In 1855 Capt. W. S. Jacob at the East India Company's Madras Observatory reported that orbital anomalies made it "highly probable" that there was a "planetary body" in this system. In the 1890s, Thomas J. J. See of the University of Chicago and the United States Naval Observatory stated that the orbital anomalies proved the existence of a dark body in the 70 Ophiuchi system with a 36-year period around one of the stars. However, Forest Ray Moulton published a paper proving that a three-body system with those orbital parameters would be highly unstable. During the 1950s and 1960s, Peter van de Kamp of Swarthmore College made another prominent series of detection claims, this time for planets orbiting Barnard's Star. Now astronomers now generally regard all the early reports of detection as erroneous not to be considered.

In 1991 Andrew Lyne, M. Bailes and S. L. Shemar claimed to have discovered a pulsar planet in orbit around PSR 1829-10, using pulsar timing variations.
The claim briefly received intense attention, but Lyne and his team soon retracted it. Confirmed discoveries. These discoveries of exoplanets. See also the list of exoplanet firsts. The three known planets of the star HR8799, as imaged by the Hale Telescope. The light from the central star was blanked out by a vector vortex coronagraph. 2MASS J044144 is a brown dwarf with a companion about 5–10 times the mass of Jupiter. It is not clear whether this companion object is a sub-brown dwarf or a planet. Coronagraphic image of AB Pictoris showing a companion (bottom left), which is either a brown dwarf or a massive planet. The data was obtained on 16 March 2003 with NACO on the VLT, using a 1.4 arcsec occulting mask on top of AB Pictoris.
As of 1 November 2015, a total of 1977 confirmed exoplanets are listed in the Extrasolar Planets Encyclopaedia, including a few that were confirmations of controversial claims from the late 1980s. The first published discovery to receive subsequent confirmation was made in 1988 by the Canadian astronomers Bruce Campbell, G. A. H. Walker, and Stephenson Yang of the University of Victoria and the University of British Columbia.  Although they were cautious about claiming a planetary detection, their radial-velocity observations suggested that a planet orbits the star Gamma Cephei. Partly because the observations were at the very limits of instrumental capabilities at the time, astronomers remained sceptical for several years about this and other similar observations. It was thought some of the apparent planets might instead have been brown dwarfs, objects intermediate in mass between planets and stars. In 1990 additional observations were published that supported the existence of the planet orbiting Gamma Cephei, but subsequent work in 1992 again raised serious doubts. Finally, in 2003, improved techniques allowed the planet's existence to be confirmed. On 9 January 1992, radio astronomers Aleksander Wolszczan and Dale Frail announced the discovery of two planets orbiting the pulsar PSR 1257+12. 

This discovery was confirmed and is generally considered to be the first definitive detection of exoplanets.
Follow-up observations solidified these results and confirmation of a third planet in 1994 revived the topic in the popular press. These pulsar planets are believed to have formed from the unusual remnants of the supernova that produced the pulsar, in a second round of planet formation, or else to be the remaining rocky cores of gas giants that somehow survived the supernova and then decayed into their current orbits.On 6 October 1995, Michel Mayor and Didier Queloz of the University of Geneva announced the first definitive detection of an exoplanet orbiting a main-sequence star, namely the nearby G-type star 51 Pegasi.
This discovery, made at the Observatoire de Haute-Provence, ushered in the modern era of exoplanetary discovery. Technological advances, most notably in high-resolution spectroscopy, led to the rapid detection of many new exoplanets: astronomers could detect exoplanets indirectly by measuring their gravitational influence on the motion of their host stars. More extrasolar planets were later detected by observing the variation in a star's apparent luminosity as an orbiting planet passed in front of it. Initially, most known exoplanets were massive planets that orbited very close to their parent stars. 

Astronomers were surprised by these as there "hot Jupiters", because theories of planetary formation had indicated that giant planets should only form at large distances from stars.
But eventually more planets of other sorts were found, and it is now clear that hot Jupiters are a minority of exoplanets. In 1999, Upsilon Andromedae became the first main-sequence star known to have multiple planets. Kepler-16 contains the first discovered planet that orbits around a binary main-sequence star system. On 26 February 2014, NASA announced the discovery of 715 newly verified exoplanets around 305 stars by the Kepler Space Telescope. These exoplanets were checked using a statistical technique called "verification by multiplicity".
Prior to these results, most confirmed planets were gas giants comparable in size to Jupiter or larger as they are more easily detected, but the Kepler planets are mostly between the size of Neptune and the size of Earth.On 23 July 2015, NASA announced Kepler-452b, a near-Earth-size planet orbiting the habitable zone of a G2-type star. Candidate discoveries. As of March 2014, NASA's Kepler mission had identified more than 2,900 planetary candidates, several of them being nearly Earth-sized and located in the habitable zone, some around Sun-like stars. Kepler mission – new exoplanet candidates – as the answers still remains as elusive as the Earth's core.