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« I don't feel the least humble before the vastness of the heavens. The stars may be large, but they cannot think or love; and these are qualities which impress me far more than size does. » – Frank Ramsey, On There Being No Discussable Subject, 1925

« – Urithi 4, Mission Control here. Do you receive us? Do you receive us, Urithi 4?

– Mission Control, Urithi 4 here. Praise be to God and the Prophet, we receive you. We see Asherah. She's beautiful. »

The solar system of Utu, Ea 's star. Mass measures are given in the picture as Earth's-masses (Me), 1 Me being about 6.0 million billion billion kg; distances are given in astronomical units (AU), 1 AU being equivalent to Earth's average distance from the Sun, or about 150 million km. Body sizes are proportional to each other, as are distances between bodies, but sizes and distances are not proportional to each other (if they were, even the star would be just barely visible).

As a G4-class star , Utu is somewhat smaller and colder than our Sun, which is a G2-class star (Utu has a radius of 650,000 km and a surface temperature of 5530 K, whereas the Sun has a radius of 700,000 km and a surface temperature of 5778 K).
In broad strokes, Utu's system is similar to our own, if slightly smaller, with a number of rocky planets surrounded by gas giants on wider orbits. The outer gas giants protect the inner planet from major meteorite impact by absorbing or deflecting most objects on irregular orbits, or by capturing them as moons.

Asherah (0.38 Me, 0.64 AU) is the closest planet to Utu. In its formation it was closer still; as the high temperatures slowed the consolidation of its crust, its surface is now covered in crystals, mainly quartz, that make it highly reflective. After the moons Nanna and Ereshkigal, it's the brightest object in Ea's night sky. No moons.
Ea (0.64 Me, 1.03 AU) is the only planet in the system with liquid water oceans and an oxygen-rich atmosphere. As such, it was chosen for human colonization. Its native red flora is well visible from space. Two moons: Nanna, Ereshkigal.
Attis (0.18 Me, 1.9 AU) and Cybele (0.31 Me, 1.9 AU) are twin planets that orbit around each other as they revolve around Utu. The tidal forces due to each other's gravity deform and fissure the crust (compare Jupiter's moon Io ). They are being considered for mining because of the deposits of heavy radioactive metals brought to surface by this process. No moons.
Dagon (0.79 Me, 2.6 AU) is the farthest rocky planet. Like Venus , it has a hot core but no significant tectonic activity; instead, pressure builds up for hundreds of millions of years until it is released in a planet-wide eruption that melts most of the crust. Today the surface is frozen and static, but the immense scars of the last eruption are still visible. Thanks to the periodic outgassing, it's the only rocky planet in the system other than Ea with a significant atmosphere. One moon: Astarte.
Bel (256 Me, 6.1 AU) is the first gas giant, and the only planet of Utu's system with visible rings. It's mostly composed of hydrogen, helium, and ammonia, and its surface, like Jupiter's, is divided in parallel belts of alternately rising and falling gases (similarly to what occurs in Ea's own atmosphere ). Four major moons: Sargon, Enheduanna, Rimush, Naram-Sin.
Marduk (298 Me, 13.2 AU) is the largest planet in the system. Its atmosphere appears bluish due to a presence of methane, which glows where it's ionized by electric storms. A counterclockwise cyclone, known as the Eye of Marduk, persists in the northern hemisphere. Three major moons: Hammurabi, Nebuchadnezzar, Nabonidus.
Ashur (156 Me, 21.8 AU) is the farthest planet of Utu's system. At the present is poorly studied. Three major moons: Tukulti-Ninurta, Tiglat-Pileser, Shalmaneser.
The orbit of Ashur was reached just before the Planetary War by the Hanno 3 probe. The further regions of Utu's system, containing a large number of dwarf planets, comets, and other such objects, are to date relatively unknown.

EDIT 13-03-20: added major moons, changed Utu's measurement to Earth-masses.

Related information:
- Ea, introduction
- A physical and political map of Ea
- UNSS Utnapishtim , the starship that brough humans to Ea, and its commander
- The world they left
- A first sample of Ea's life

Description

« I don't feel the least humble before the vastness of the heavens. The stars may be large, but they cannot think or love; and these are qualities which impress me far more than size does. » – Frank Ramsey, On There Being No Discussable Subject, 1925

« – Urithi 4, Mission Control here. Do you receive us? Do you receive us, Urithi 4?

– Mission Control, Urithi 4 here. Praise be to God and the Prophet, we receive you. We see Asherah. She's beautiful. »

The solar system of Utu, Ea 's star. Mass measures are given in the picture as Earth's-masses (Me), 1 Me being about 6.0 million billion billion kg; distances are given in astronomical units (AU), 1 AU being equivalent to Earth's average distance from the Sun, or about 150 million km. Body sizes are proportional to each other, as are distances between bodies, but sizes and distances are not proportional to each other (if they were, even the star would be just barely visible).

As a G4-class star , Utu is somewhat smaller and colder than our Sun, which is a G2-class star (Utu has a radius of 650,000 km and a surface temperature of 5530 K, whereas the Sun has a radius of 700,000 km and a surface temperature of 5778 K).
In broad strokes, Utu's system is similar to our own, if slightly smaller, with a number of rocky planets surrounded by gas giants on wider orbits. The outer gas giants protect the inner planet from major meteorite impact by absorbing or deflecting most objects on irregular orbits, or by capturing them as moons.

Asherah (0.38 Me, 0.64 AU) is the closest planet to Utu. In its formation it was closer still; as the high temperatures slowed the consolidation of its crust, its surface is now covered in crystals, mainly quartz, that make it highly reflective. After the moons Nanna and Ereshkigal, it's the brightest object in Ea's night sky. No moons.
Ea (0.64 Me, 1.03 AU) is the only planet in the system with liquid water oceans and an oxygen-rich atmosphere. As such, it was chosen for human colonization. Its native red flora is well visible from space. Two moons: Nanna, Ereshkigal.
Attis (0.18 Me, 1.9 AU) and Cybele (0.31 Me, 1.9 AU) are twin planets that orbit around each other as they revolve around Utu. The tidal forces due to each other's gravity deform and fissure the crust (compare Jupiter's moon Io ). They are being considered for mining because of the deposits of heavy radioactive metals brought to surface by this process. No moons.
Dagon (0.79 Me, 2.6 AU) is the farthest rocky planet. Like Venus , it has a hot core but no significant tectonic activity; instead, pressure builds up for hundreds of millions of years until it is released in a planet-wide eruption that melts most of the crust. Today the surface is frozen and static, but the immense scars of the last eruption are still visible. Thanks to the periodic outgassing, it's the only rocky planet in the system other than Ea with a significant atmosphere. One moon: Astarte.
Bel (256 Me, 6.1 AU) is the first gas giant, and the only planet of Utu's system with visible rings. It's mostly composed of hydrogen, helium, and ammonia, and its surface, like Jupiter's, is divided in parallel belts of alternately rising and falling gases (similarly to what occurs in Ea's own atmosphere ). Four major moons: Sargon, Enheduanna, Rimush, Naram-Sin.
Marduk (298 Me, 13.2 AU) is the largest planet in the system. Its atmosphere appears bluish due to a presence of methane, which glows where it's ionized by electric storms. A counterclockwise cyclone, known as the Eye of Marduk, persists in the northern hemisphere. Three major moons: Hammurabi, Nebuchadnezzar, Nabonidus.
Ashur (156 Me, 21.8 AU) is the farthest planet of Utu's system. At the present is poorly studied. Three major moons: Tukulti-Ninurta, Tiglat-Pileser, Shalmaneser.
The orbit of Ashur was reached just before the Planetary War by the Hanno 3 probe. The further regions of Utu's system, containing a large number of dwarf planets, comets, and other such objects, are to date relatively unknown.

EDIT 13-03-20: added major moons, changed Utu's measurement to Earth-masses.

Related information:
- Ea, introduction
- A physical and political map of Ea
- UNSS Utnapishtim , the starship that brough humans to Ea, and its commander
- The world they left
- A first sample of Ea's life