Pandora's planet

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In case of fixed limb-darkening parameters during sampling, Pandora creates a lookup table of occultation values before the sampling commences. This procedure calculates a 2D grid of occultation values covering planet-to-star radius ratios 0 < ( R p/ R s) < 0.2 and distances from the stellar center 0 < z< 1 + ( R p/ R s) with 300 values along each axis, which we verified to result in errors <1 ppm. Afterwards, the occultation values are calculated for each model from this rectilinear 2D grid with a bilinear interpolation from their nearest neighbors. This procedure only requires four floats to be obtained from memory, and at most eight multiplications, one division, and thirteen additions per data point.

The obesus rotundus ( Rumut in Na'vi) is a tree that resembles a puffball tree. [1] Pseudocycas altissima [ edit ] If the exposure time of a light curve is longer than the time scale of the variation due to the signal, then this signal becomes temporally smeared ( Kipping 2010). In Pandora, this temporal smearing can be compensated for by using supersampling of the light curve, which naturally comes at a higher computational cost and which is thus optional for users. When ACB shares the daytime sky with ACA, at its closest it adds about half a percent to the total illumination. When the 2 stars are close together in the sky, the effect of ACB's more orange light is unnoticeable. But, as they separate over the years, an orange tint may be seen in areas shadowed from ACA's direct illumination. At its most distant, ACB is about 2,700 times dimmer than ACA and does not produce noticeable lighting effects. However, it still appears as a blindingly-bright tiny orange disk in the sky. Because of its high axial tilt (29°), Pandora exhibits considerable annual variation in the day-to-night ratio. In addition, its elliptical orbit produces seasonal temperature variations and a range in daytime illumination of about ten percent. Clouded Forest · Dusk Valley · Grave's Bog · Hallelujah Mountains ( Mons Veritatis · Iknimaya) · Hanging Gardens · Highlands · Kinglor Forest · Kxanìa Taw · Needle Hills · Plains of Goliath · Skycliffs · Stalker's Valley · Swotulu · Tantalus · Torukä Na'rìng · Three Brothers · Upper Plains · Vaderas Hollow · Valley of Mo'ara · Valley of Origins · Wetlands

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Due to Pandora's lower gravity, most creatures on Pandora are hexapods (six-legged), although the Na'vi resemble Humans and have only two legs. Creatures roam the air and forest canopy below, similar to Earth's animals, but on a scale several times larger. Pandora receives significant light from Alpha Centauri B (ACB). As a result, Pandoran nights are never dark during half of the Polyphemian year, but instead are more like Earthly dusk. At the closest point in its orbit, ACB is about 2,300 times as bright as Earth's full moon; at its furthest point, it is still one hundred and seventy times as bright. During the other half of the year when ACB is in the daytime sky, many Pandoran nights are illuminated by both Polyphemus's huge disk and the reflected light from other nearby moons. Truly dark nights are uncommon. Polyphemus occasionally eclipses ACB at night for about one hundred minutes, but the light reflected by the planet still keeps the night from being dark. While the search for planets beyond the Solar System (exoplanets) has greatly benefited from the transit method in search for periodic occultations of a star by its planets (e.g., Batalha et al. 2013; Zeng et al. 2019), no moon around any exoplanet has been securely discovered as of today. With over 3400 exoplanets found by the transit method, we naturally wonder if any exo-moons could be detected around them. The detection of exomoon transits is very difficult due to the complex orbital motion, the occurrence of combined transits of an exoplanet with its moon (or moons), possible planet-moon eclipses, and potentially due to the small physical radii of exomoons, all of which make phase-folding approaches similar to those used for transiting exoplanets ( Kovâcs et al. 2002; Hippke & Heller 2019) inefficient. Indeed, methods like the orbital sampling effect ( Heller 2014) or transit origami ( Kipping 2021) neglect about half of the tiny signal, details depending on the planet-moon orbital separation, and the transit geometry ( Heller & Hippke 2022). Plants are subject to greater wind force, as the greater air density means that the moving air carries more kinetic energy and more momentum, and the plants, leaves, stems, branches, and trunks must all have a greater strength and/or flexibility to resist it. The star is at the origin of our ( x, y) coordinate system and all distances are measured in stellar radii. The distance of the center of any transiting body (planet or moon) from the center of the stellar disk, which is required for the flux calculations, is thus simply given as .

Corner plot from the UltraNest retrieval of the system shown in Fig. 3, but with four transit epochs. We note that R s is given in units of R ⊙, a b in units of AU, and M p in units of Jupiter masses. Due to the small number of transits, the posterior is multimodal for combinations of P pm and τ pm. Additional transits would constrain the system much better.As for the frequency and duration of planet-moon eclipses, they are rare in the Solar System and they can be expected to be rare in most exomoon scenarios. The highest frequency and longest duration occurs in an edge-on geometry, when the planet–moon orbit is in alignment with the line of sight. In this case, the maximum fraction of the planet-moon orbit spent in eclipse is roughly 2 R p/( πa pm). For the Earth–Moon system, this corresponds to about 1% of the time; also, for the Galilean moons around Jupiter, this corresponds to about 10.4% (Io), 6.6% (Europa), 4.1% (Ganymede), and 2.3% (Callisto), respectively. Athena is the principal member or primary of the binary system, being slightly larger and more luminous than Sol. It is a solar-like main sequence star with a similar yellowish-white color, whose stellar classification is spectral type G2 V. From mutual orbital parameters, Athena is about 10% more massive than Sol, with a radius about 23% larger.

Leri Greer, a designer at Weta Workshop, explained the unusual day/night cycle experienced by the Na'vi, who inhabit a moon orbiting a planet, that in turn orbits around a star. One of Anvil's best-known short stories is "Pandora's Planet", which appeared first in Astounding in September 1956. [7] It has since been reprinted several times, and also combined with the other stories in his Pandora series into a full length "fixed-up" novel, Pandora's Legions. [8] Before calculating any data points for the Kepler ellipse, however, Pandora estimates if the planet–moon barycenter is sufficiently close to the stellar disk for any transits to occur in the first place. If the planet-moon barycenter is farther away from the origin of the coordinate system than the sum of the stellar radius and the maximum possible deflection of the moon from the planet, then occultations are geometrically impossible. In this case, no calculations are made and the flux in the model light curve is set to 1. This saves CPU time out of transit.Ngim-a Kilvan: The Na'vi city was the first built by the Na'vi on a portion of the Hallelujah Mountains that drifts over the southern coast. In English its name is Long River, given the unobtanium shard floats over the Or'ant river basin. Ngim-a Kilvan is also home to a sizable population of Eloran, Tarlac and Orions. In the original script, Pandora's flora was mostly violet, blue and cyan in color, but ultimately director James Cameron decided to go with the more familiar green so as to keep the scenery more believable. [11] The pseudocycas altissima ( Tsyorina'wll in Na'vi) is a plant akin to a tall Earth cycad. [1] Hometrees [ edit ]