SCIENCE&ARTWORK | THE HOKU | ASTROPHYSICS | PART 2

Hokushoku's vast oceans cover around 75% of the planet's surface

HOKUSHOKU / Auot’zae, literal for "The World"

Tropical Superterran

About 4.60 Gyr old

2.54 Earth-masses, or 15.168×10^24 kg

1.42 Earth-radii, 9050 km radius

12.28 m/s², 1.25 G

Mean density 4.84 g/cm³

Escape velocity ~15 km/s at the surface

Semi-major axis 0.805 AU

Orbital eccentricity 0.014

Orbital period 0,72 Earth-years, or ~263.28 Earth-days

or 1 Hoku-years = 200.06 days of ~31h35min each.

            (add a leap day every 15.64 Hoku-years)

Axial tilt ~23.9° (current era)

EQ. Temperature 253 K (-20 °C)

Atmosphere 77.9% N2, 20.0% O2, 1.1% H2O vapor, 0.9% Helium, 0.078% CO2, 0.011% SO2, 0.01% Ar & Others (somewhat breathable for humans, poor air quality, hour-long exposure causes irritation to the eyes, nose, and respiratory tract).

~1.52 bar at sea-level.

Mean temperature between 19.7 °C with an Earth-like albedo.

Very Earth-like climate, yellow vegetation — chrysophyll pigment.

Known native species:

Hoku (Avipoda sapiens, "wise bird-feet").

Antillo.

Deathmoth.

Scute.

White peas.

With 2.01x the Earth's surface area, the continents and oceans are vast, not only allowing for large habitable spaces, but also large deserts across the two Pangea-sized continents

In natural colors it is rather difficult for us humans to distinguish vegetation from deserts because of the light yellow/orange tones, though the natives have well adapted eyes to separate soil from different types of vegetation, which had only managed to spread inland due the atmosphere's high humidity

THE MOON, NUHEZA

HOKU-b / Nuheza (moon of Hokushoku)

Rocky moon

0.0067 Earth-masses, or 4.00×10^22 kg

0.21 Earth-radii, 1340 km radius

1.43 m/s², 0.15 G

Mean density 3.78 g/cm³

Escape velocity ~2.0 km/s at the surface

Semi-major axis ~277.1 thousand km or 21.75 Earth-diameters

Orbital eccentricity 0.054

Orbital period ~26.34 Earth-days or ~8 local days

(tidally locked) (25 cycles / Hoku-year)

Exosphere trace levels of hydrogen, neon, and argon.

Mean temperature around -5 °C assuming a Moon-like albedo.

Tidal forces are on average ~2.1x That of Earth’s moon

Apparent size and brightness equivalent to that of Earth’s moon, though the tidal pull is double that of the Earth’s moon because of the mass difference between the bodies.

The moon currently orbits the planet in roughly the same orientation as its equator, which means that its orbit is very inclined, and thus, the moon is only fully full or fully new twice a year. Having a slim line of darkness or sunlit area during the other 23 cycles.

The lunar cycle of 1 Hoku-year

1 frame = 1 Hoku-day

Because Hokushoku stays close to its star, Paza, which is rather less luminous than our Sun despite having similar size, the angular size of Paza is around 0.6° in the sky (compared to the Sun's 0.5°), this makes up for slightly larger eclipse shadows over the planet.

Speaking of eclipses, the only eclipses are annular eclipses because there is a 0.02° difference between the moon's largest angular size and the angular size of Paza.

Standing on the surface of Hokushoku wouldn't feel dramatically different than on Earth, but by human standards the air has very poor quality, and coupled with the stronger gravity and thick atmosphere it may be difficult to exercise or run across large distances for time exceeding one or two hours. It feels like venturing in a volcanic island carrying extra 20 kg of cargo on your back, a task impractical to the typical human, but not impossible for trained explorers.

The moon is barely larger than Earth's moon in the sky, and the day is dictated by the main star just like on Earth, tides are noticeably more violent and tall.

- M.O. Valent, 11/12/2022

happy birthday to me!