.. default-domain:: py .. highlight:: py .. currentmodule:: SpaceCenter CelestialBody ============= .. class:: CelestialBody Represents a celestial body (such as a planet or moon). See :attr:`bodies`. .. attribute:: name The name of the body. :Attribute: Read-only, cannot be set :rtype: str .. attribute:: satellites A list of celestial bodies that are in orbit around this celestial body. :Attribute: Read-only, cannot be set :rtype: list(:class:`CelestialBody`) .. attribute:: orbit The orbit of the body. :Attribute: Read-only, cannot be set :rtype: :class:`Orbit` .. attribute:: mass The mass of the body, in kilograms. :Attribute: Read-only, cannot be set :rtype: float .. attribute:: gravitational_parameter The `standard gravitational parameter `_ of the body in :math:`m^3s^{-2}`. :Attribute: Read-only, cannot be set :rtype: float .. attribute:: surface_gravity The acceleration due to gravity at sea level (mean altitude) on the body, in :math:`m/s^2`. :Attribute: Read-only, cannot be set :rtype: float .. attribute:: rotational_period The sidereal rotational period of the body, in seconds. :Attribute: Read-only, cannot be set :rtype: float .. attribute:: rotational_speed The rotational speed of the body, in radians per second. :Attribute: Read-only, cannot be set :rtype: float .. attribute:: rotation_angle The current rotation angle of the body, in radians. A value between 0 and :math:`2\pi` :Attribute: Read-only, cannot be set :rtype: float .. attribute:: initial_rotation The initial rotation angle of the body (at UT 0), in radians. A value between 0 and :math:`2\pi` :Attribute: Read-only, cannot be set :rtype: float .. attribute:: equatorial_radius The equatorial radius of the body, in meters. :Attribute: Read-only, cannot be set :rtype: float .. method:: surface_height(latitude, 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. :param float latitude: Latitude in degrees. :param float longitude: Longitude in degrees. :rtype: float .. method:: bedrock_height(latitude, 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. :param float latitude: Latitude in degrees. :param float longitude: Longitude in degrees. :rtype: float .. method:: msl_position(latitude, longitude, reference_frame) The position at mean sea level at the given latitude and longitude, in the given reference frame. :param float latitude: Latitude in degrees. :param float longitude: Longitude in degrees. :param ReferenceFrame reference_frame: Reference frame for the returned position vector. :returns: Position as a vector. :rtype: tuple(float, float, float) .. method:: surface_position(latitude, longitude, 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. :param float latitude: Latitude in degrees. :param float longitude: Longitude in degrees. :param ReferenceFrame reference_frame: Reference frame for the returned position vector. :returns: Position as a vector. :rtype: tuple(float, float, float) .. method:: bedrock_position(latitude, longitude, 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. :param float latitude: Latitude in degrees. :param float longitude: Longitude in degrees. :param ReferenceFrame reference_frame: Reference frame for the returned position vector. :returns: Position as a vector. :rtype: tuple(float, float, float) .. method:: position_at_altitude(latitude, longitude, altitude, reference_frame) The position at the given latitude, longitude and altitude, in the given reference frame. :param float latitude: Latitude in degrees. :param float longitude: Longitude in degrees. :param float altitude: Altitude in meters above sea level. :param ReferenceFrame reference_frame: Reference frame for the returned position vector. :returns: Position as a vector. :rtype: tuple(float, float, float) .. method:: altitude_at_position(position, reference_frame) The altitude, in meters, of the given position in the given reference frame. :param tuple position: Position as a vector. :param ReferenceFrame reference_frame: Reference frame for the position vector. :rtype: float .. method:: latitude_at_position(position, reference_frame) The latitude of the given position, in the given reference frame. :param tuple position: Position as a vector. :param ReferenceFrame reference_frame: Reference frame for the position vector. :rtype: float .. method:: longitude_at_position(position, reference_frame) The longitude of the given position, in the given reference frame. :param tuple position: Position as a vector. :param ReferenceFrame reference_frame: Reference frame for the position vector. :rtype: float .. attribute:: sphere_of_influence The radius of the sphere of influence of the body, in meters. :Attribute: Read-only, cannot be set :rtype: float .. attribute:: is_star Whether or not the body is a star. :Attribute: Read-only, cannot be set :rtype: bool .. attribute:: has_solid_surface Whether or not the body has a solid surface. :Attribute: Read-only, cannot be set :rtype: bool .. attribute:: has_atmosphere ``True`` if the body has an atmosphere. :Attribute: Read-only, cannot be set :rtype: bool .. attribute:: atmosphere_depth The depth of the atmosphere, in meters. :Attribute: Read-only, cannot be set :rtype: float .. method:: atmospheric_density_at_position(position, reference_frame) The atmospheric density at the given position, in :math:`kg/m^3`, in the given reference frame. :param tuple position: The position vector at which to measure the density. :param ReferenceFrame reference_frame: Reference frame that the position vector is in. :rtype: float .. attribute:: has_atmospheric_oxygen ``True`` if there is oxygen in the atmosphere, required for air-breathing engines. :Attribute: Read-only, cannot be set :rtype: bool .. method:: temperature_at(position, reference_frame) The temperature on the body at the given position, in the given reference frame. :param tuple position: Position as a vector. :param ReferenceFrame reference_frame: The reference frame that the position is in. :rtype: float .. 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. .. method:: density_at(altitude) Gets the air density, in :math:`kg/m^3`, for the specified altitude above sea level, in meters. :param float altitude: :rtype: float .. 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. .. method:: pressure_at(altitude) Gets the air pressure, in Pascals, for the specified altitude above sea level, in meters. :param float altitude: :rtype: float .. attribute:: biomes The biomes present on this body. :Attribute: Read-only, cannot be set :rtype: set(str) .. method:: biome_at(latitude, longitude) The biome at the given latitude and longitude, in degrees. :param float latitude: :param float longitude: :rtype: str .. attribute:: flying_high_altitude_threshold The altitude, in meters, above which a vessel is considered to be flying "high" when doing science. :Attribute: Read-only, cannot be set :rtype: float .. attribute:: space_high_altitude_threshold The altitude, in meters, above which a vessel is considered to be in "high" space when doing science. :Attribute: Read-only, cannot be set :rtype: float .. attribute:: 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. :Attribute: Read-only, cannot be set :rtype: :class:`ReferenceFrame` .. figure:: /images/reference-frames/celestial-body.png :align: center Celestial body reference frame origin and axes. The equator is shown in blue, and the prime meridian in red. .. attribute:: 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. :Attribute: Read-only, cannot be set :rtype: :class:`ReferenceFrame` .. attribute:: 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 axes rotate with the orbital prograde/normal/radial directions. * 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. :Attribute: Read-only, cannot be set :rtype: :class:`ReferenceFrame` .. method:: position(reference_frame) The position of the center of the body, in the specified reference frame. :param ReferenceFrame reference_frame: The reference frame that the returned position vector is in. :returns: The position as a vector. :rtype: tuple(float, float, float) .. method:: velocity(reference_frame) The linear velocity of the body, in the specified reference frame. :param ReferenceFrame reference_frame: The reference frame that the returned velocity vector is in. :returns: 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. :rtype: tuple(float, float, float) .. method:: rotation(reference_frame) The rotation of the body, in the specified reference frame. :param ReferenceFrame reference_frame: The reference frame that the returned rotation is in. :returns: The rotation as a quaternion of the form :math:`(x, y, z, w)`. :rtype: tuple(float, float, float, float) .. method:: direction(reference_frame) The direction in which the north pole of the celestial body is pointing, in the specified reference frame. :param ReferenceFrame reference_frame: The reference frame that the returned direction is in. :returns: The direction as a unit vector. :rtype: tuple(float, float, float) .. method:: angular_velocity(reference_frame) The angular velocity of the body in the specified reference frame. :param ReferenceFrame reference_frame: The reference frame the returned angular velocity is in. :returns: 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. :rtype: tuple(float, float, float)