Under the Moons of Alchibah All Times In Alchibah Hours and Days
Alc3 Planet Alchibah Rotational period 20 hours 18 deg/hr.
Moon 1 Oliver Dia. 950 miles.
Orbital Radius. 138,000 miles. Period 16.21 Days.
Absolute Orbital Motion 1.1 deg/hr. Relative Motion 16.9 deg/hr.
Angular diameter .4 degrees.
Maximum Luminosity Luna = 1 0 .72
Tidal Influence Luna = 100 32.4%.
Rotational period 46 hours. Surface Gravity 7% Earth Standard.
Moon 2 Carter Dia. 185 miles.
Orbital Radius 16,926 miles. Period 13.7 hours.
Absolute Orbital Motion 26.2 deg/hr. Relative Motion -8.2 deg/hr.
Angular diameter .63 degrees.
Maximum Luminosity Luna = 1 1 .85
Tidal Influence Luna = 100 16.8%.
Rotational period 13.7 hours. One side will always face Alchibah. Surface Gravity TBD. Less than 1% Earth Standard.
Earths Moon Absolute Orbital Motion 0.54 deg/hr. Relative Motion 14.46 deg/hr. Angular diameter .5 deg. Surface Gravity 1/6th Earth Standard.
The maximum light reflected by both moons to the planet Alchibah will average nearly 260% greater than that which Luna reflects to the Earth.
The moons tidal effects, when aligned, will be a bit less than half of what Earth experiences. Due to the differing orbital periods most of the time the tidal effects will be at odds and fighting each other. when they are at the point of greatest interference the resultant maximal tide will be about 15% of that experienced on Earth. This will be when the moons are separated in their orbits by some 90 degrees.
View from above Northern Planetary Pole. Flag showing constant reference position. A tangent to the planet at the base of the flag will give a reference horizon line.
The direction of sunrise on Alchibah has been designated East. The outer moon Oliver, when viewed against the fixed stars, will seem to drift slowly westerly across the night sky in a manner very similar to Earth’s Luna. Because Carter, the inner moon, circles Alchibah so much faster than Oliver, or earths moon, it will be seen to travel towards the East as night progresses at a rate slightly greater than 8 degrees an hour and will also seem to change phases. See Illustration. Both moons are heavily cratered as would be expected.
The angular diameter of the star Alchibah as seen from the planet is about 0.3 degrees, slightly larger than half that of the Sun as seen from the Earth, though Alchibah is of course much brighter. This smaller angular diameter, combined with a 200 million mile distance from the planet, means that even with Oliver and Carter having diameters less than that of Luna, eclipses will be quite common and that both moons are capable of totally eclipsing Alchibah. The relative closeness of both moons to the planet is another factor which will greatly increase the frequency of eclipses. Still another is their more rapid orbital periods. With Carter being so close to the planetary surface it should be possible to see it being eclipsed almost every night.
The above discussion is somewhat simplified as nightly positional changes against the stellar background will also be influenced by Alchibah’s 922 day orbital period and axial inclination. For complete Moon and Tide details see the Alchibah System Ephemeris.