# CelestialBody¶

class CelestialBody

Represents a celestial body (such as a planet or moon). See bodies().

std::string name()

The name of the body.

Game Scenes: All
std::vector<CelestialBody> satellites()

A list of celestial bodies that are in orbit around this celestial body.

Game Scenes: All
Orbit orbit()

The orbit of the body.

Game Scenes: All
float mass()

The mass of the body, in kilograms.

Game Scenes: All
float gravitational_parameter()

The standard gravitational parameter of the body in $$m^3s^{-2}$$.

Game Scenes: All
float surface_gravity()

The acceleration due to gravity at sea level (mean altitude) on the body, in $$m/s^2$$.

Game Scenes: All
float rotational_period()

The sidereal rotational period of the body, in seconds.

Game Scenes: All
float rotational_speed()

The rotational speed of the body, in radians per second.

Game Scenes: All
double rotation_angle()

The current rotation angle of the body, in radians. A value between 0 and $$2\pi$$

Game Scenes: All
double initial_rotation()

The initial rotation angle of the body (at UT 0), in radians. A value between 0 and $$2\pi$$

Game Scenes: All
float equatorial_radius()

The equatorial radius of the body, in meters.

Game Scenes: All
double surface_height(double latitude, double longitude)

The height of the surface relative to mean sea level, in meters, at the given position. When over water this is equal to 0.

Parameters: latitude – Latitude in degrees. longitude – Longitude in degrees. All
double bedrock_height(double latitude, double longitude)

The height of the surface relative to mean sea level, in meters, at the given position. When over water, this is the height of the sea-bed and is therefore negative value.

Parameters: latitude – Latitude in degrees. longitude – Longitude in degrees. All
std::tuple<double, double, double> msl_position(double latitude, double longitude, ReferenceFrame reference_frame)

The position at mean sea level at the given latitude and longitude, in the given reference frame.

Parameters: latitude – Latitude in degrees. longitude – Longitude in degrees. reference_frame – Reference frame for the returned position vector. Position as a vector. All
std::tuple<double, double, double> surface_position(double latitude, double longitude, ReferenceFrame reference_frame)

The position of the surface at the given latitude and longitude, in the given reference frame. When over water, this is the position of the surface of the water.

Parameters: latitude – Latitude in degrees. longitude – Longitude in degrees. reference_frame – Reference frame for the returned position vector. Position as a vector. All
std::tuple<double, double, double> bedrock_position(double latitude, double longitude, ReferenceFrame reference_frame)

The position of the surface at the given latitude and longitude, in the given reference frame. When over water, this is the position at the bottom of the sea-bed.

Parameters: latitude – Latitude in degrees. longitude – Longitude in degrees. reference_frame – Reference frame for the returned position vector. Position as a vector. All
std::tuple<double, double, double> position_at_altitude(double latitude, double longitude, double altitude, ReferenceFrame reference_frame)

The position at the given latitude, longitude and altitude, in the given reference frame.

Parameters: latitude – Latitude in degrees. longitude – Longitude in degrees. altitude – Altitude in meters above sea level. reference_frame – Reference frame for the returned position vector. Position as a vector. All
double altitude_at_position(std::tuple<double, double, double> position, ReferenceFrame reference_frame)

The altitude, in meters, of the given position in the given reference frame.

Parameters: position – Position as a vector. reference_frame – Reference frame for the position vector. All
double latitude_at_position(std::tuple<double, double, double> position, ReferenceFrame reference_frame)

The latitude of the given position, in the given reference frame.

Parameters: position – Position as a vector. reference_frame – Reference frame for the position vector. All
double longitude_at_position(std::tuple<double, double, double> position, ReferenceFrame reference_frame)

The longitude of the given position, in the given reference frame.

Parameters: position – Position as a vector. reference_frame – Reference frame for the position vector. All
float sphere_of_influence()

The radius of the sphere of influence of the body, in meters.

Game Scenes: All
bool has_atmosphere()

true if the body has an atmosphere.

Game Scenes: All
float atmosphere_depth()

The depth of the atmosphere, in meters.

Game Scenes: All
double atmospheric_density_at_position(std::tuple<double, double, double> position, ReferenceFrame reference_frame)

The atmospheric density at the given position, in $$kg/m^3$$, in the given reference frame.

Parameters: position – The position vector at which to measure the density. reference_frame – Reference frame that the position vector is in. All
bool has_atmospheric_oxygen()

true if there is oxygen in the atmosphere, required for air-breathing engines.

Game Scenes: All
double temperature_at(std::tuple<double, double, double> position, ReferenceFrame reference_frame)

The temperature on the body at the given position, in the given reference frame.

Parameters: position – Position as a vector. reference_frame – The reference frame that the position is in. All

Note

This calculation is performed using the bodies current position, which means that the value could be wrong if you want to know the temperature in the far future.

double density_at(double altitude)

Gets the air density, in $$kg/m^3$$, for the specified altitude above sea level, in meters.

Parameters: All

Note

This is an approximation, because actual calculations, taking sun exposure into account to compute air temperature, require us to know the exact point on the body where the density is to be computed (knowing the altitude is not enough). However, the difference is small for high altitudes, so it makes very little difference for trajectory prediction.

double pressure_at(double altitude)

Gets the air pressure, in Pascals, for the specified altitude above sea level, in meters.

Parameters: All
std::set<std::string> biomes()

The biomes present on this body.

Game Scenes: All
std::string biome_at(double latitude, double longitude)

The biome at the given latitude and longitude, in degrees.

Parameters: All
float flying_high_altitude_threshold()

The altitude, in meters, above which a vessel is considered to be flying “high” when doing science.

Game Scenes: All
float space_high_altitude_threshold()

The altitude, in meters, above which a vessel is considered to be in “high” space when doing science.

Game Scenes: All
ReferenceFrame reference_frame()

The reference frame that is fixed relative to the celestial body.

• The origin is at the center of the body.
• The axes rotate with the body.
• The x-axis points from the center of the body towards the intersection of the prime meridian and equator (the position at 0° longitude, 0° latitude).
• The y-axis points from the center of the body towards the north pole.
• The z-axis points from the center of the body towards the equator at 90°E longitude.
Game Scenes: All

Celestial body reference frame origin and axes. The equator is shown in blue, and the prime meridian in red.

ReferenceFrame non_rotating_reference_frame()

The reference frame that is fixed relative to this celestial body, and orientated in a fixed direction (it does not rotate with the body).

• The origin is at the center of the body.
• The axes do not rotate.
• The x-axis points in an arbitrary direction through the equator.
• The y-axis points from the center of the body towards the north pole.
• The z-axis points in an arbitrary direction through the equator.
Game Scenes: All
ReferenceFrame orbital_reference_frame()

The reference frame that is fixed relative to this celestial body, but orientated with the body’s orbital prograde/normal/radial directions.

• The origin is at the center of the body.
• The x-axis points in the orbital anti-radial direction.
• The y-axis points in the orbital prograde direction.
• The z-axis points in the orbital normal direction.
Game Scenes: All
std::tuple<double, double, double> position(ReferenceFrame reference_frame)

The position of the center of the body, in the specified reference frame.

Parameters: reference_frame – The reference frame that the returned position vector is in. The position as a vector. All
std::tuple<double, double, double> velocity(ReferenceFrame reference_frame)

The linear velocity of the body, in the specified reference frame.

Parameters: reference_frame – The reference frame that the returned velocity vector is in. The velocity as a vector. The vector points in the direction of travel, and its magnitude is the speed of the body in meters per second. All
std::tuple<double, double, double, double> rotation(ReferenceFrame reference_frame)

The rotation of the body, in the specified reference frame.

Parameters: reference_frame – The reference frame that the returned rotation is in. The rotation as a quaternion of the form $$(x, y, z, w)$$. All
std::tuple<double, double, double> direction(ReferenceFrame reference_frame)

The direction in which the north pole of the celestial body is pointing, in the specified reference frame.

Parameters: reference_frame – The reference frame that the returned direction is in. The direction as a unit vector. All
std::tuple<double, double, double> angular_velocity(ReferenceFrame reference_frame)

The angular velocity of the body in the specified reference frame.

Parameters: reference_frame – The reference frame the returned angular velocity is in. The angular velocity as a vector. The magnitude of the vector is the rotational speed of the body, in radians per second. The direction of the vector indicates the axis of rotation, using the right-hand rule. All