Extraterrestrial skies in the Tendor System

In astronomy, an extraterrestrial sky is a view of outer space from the surface of an astronomical body other than Anteria.

The only extraterrestrial sky that has been directly observed and photographed by astronauts is that of the Moon. The sky of Stratos has been observed by space probes designed to land on the surface and transmit images back to Anteria.

Characteristics of extraterrestrial sky appear to vary substantially due to a number of factors. An extraterrestrial atmosphere, if present, has a large bearing on visible characteristics. The atmosphere's density and chemical composition can contribute to differences in colour, opacity (including haze) and the presence of clouds. Astronomical objects may also be visible and can include natural satellites, rings, star systems and nebulas and other planetary system bodies.

Slahonus

Because Slahonus has no atmosphere, the view of planets and other celestial bodies would be no different than viewing them from orbit.

The Sun has a big difference in angular diameter due to its orbit's eccentricity, ranging from 2.261° to 1.558° (The Sun from Anteria has an angular diameter of 31' for example). Thus, the apparent magnitude of the Sun also fluctuates between -29.96 at perihelion to -29.15 at aphelion.

Other planets viewed from Slahonus

Out of all the objects of the Tendor System (Sun excluded) the closest object from Slahonus is Anteria with an apparent magnitude of -4.09 at the closest approach possible. Anteria would look be a bright blue dot in the Slahonian sky, accompanied by the Moon, with a magnitude of +0.00 at the closest approach. The Moon and Anteria would look like binary stars, merging every two weeks and gaining maximal apparent distance 1 week later. The maximum apparent distance is of 0.21°. Other planets are also visible, just less bright than on Anteria. The brightest planet would be Aurious with a magnitude around -7.40.

Anteria

Anteria has an atmosphere : The sky is sometimes covered by clouds, making observation impossible. The Sun has an angular diameter of 0.5334° from Anteria, making it 3 times smaller than on Slahonus at aphelion. The Sun's magnitude is approximatively of -26.83, varying slightly as the planet orbits around the star.

Other planets from Anteria

The most proeminent object excluding the Sun is the Moon, with an apparent magnitude of -12.7 and an angular diameter of 0.5178°, similar to the Sun. Slahonus has a magnitude of -0.55 during its crescent phase, meaning that it is in the brightest phase. Slahonus has an angular diameter varying between 0.0035° and 0.0029° and looks like an orange dot in the sky, visible after sunset or before sunrise. Stratos is the third brightest planet visible from Anteria, with a magnitude varying between -4.26 at opposition and -3.66 near solar conjunction. It has an angular diameter of 0.0017° at opposition, meaning that it is smaller than Slahonus visually. The Stratoshian Moons are visible in a telescope, with a magnitude of around +10. Bieruta would be seen as a orange dot of magnitude -3.51, and the same angular diameter than Stratos, meaning that a perfect occultation of Bieruta by Stratos could possibly happen, although very rare. The Bierutan moons are very dim and their angular separation is too small to permit an Anterian observer to see them correctly. Aurious, the biggest planet of the Tendor System, is the brightest of all, with a magnitude of -7.50 at full opposition, it looks like a bright violet dot illuminating the sky. It also disturbs deep sky observations to some extent. Aurious has an angular diameter of about 0.0063°, making it the biggest planet too. Aurious's moons are also visible with binoculars or a telescope, and you can see them orbiting around Aurious and changing position every day. Aurious's rings are also visible with a telescope. Nirduk looks like a pale beige dot, of magnitude -7.12 at opposition, due to its high albedo. It also ruins deep sky observations and some people mistake Nirduk with UFOs. The planet has an angular diameter of about 0.003°, which means that Nirduk has approximatively the same size as Slahonus. The Nirduki rings are not visible in the visible spectrum and they weren't discovered before the 1980s. Tsanfau, the last planet of the Tendor System, is a dark blue dot, similar to Anteria from other planets. Tsanfau has an average magnitude of -4.83 at opposition, although it looks fainter due to its color ; The gas giant has an angular diameter of 0.0011°, meaning that it is the smallest planet seen from Anteria.