在 python 中为轨道绘制一个球体

Question

如何在(384400,0,0) 的位置放置一个半径为1737 的球体？

这个球体将是我轨迹中的月亮。

代码中的其他一切都很好，我只是不知道如何在该位置添加一个具有该半径的球体。

import numpy as np
from scipy.integrate import odeint
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D

me = 5.974 * 10 ** (24)  #  mass of the earth                                     
mm = 7.348 * 10 ** (22)  #  mass of the moon                                      
G = 6.67259 * 10 ** (-20)  #  gravitational parameter                             
re = 6378.0  #  radius of the earth in km                                         
rm = 1737.0  #  radius of the moon in km                                          
r12 = 384400.0  #  distance between the CoM of the earth and moon                 
M = me + mm

pi1 = me / M
pi2 = mm / M
mue = 398600.0  #  gravitational parameter of earth km^3/sec^2                    
mum = G * mm  #  grav param of the moon                                           
mu = mue + mum
omega = np.sqrt(mu / r12 ** 3)
nu = -129.21 * np.pi / 180  #  true anomaly angle in radian                       

x = 327156.0 - 4671
#  x location where the moon's SOI effects the spacecraft with the offset of the  
#  Earth not being at (0,0) in the Earth-Moon system                              
y = 33050.0   #  y location                                                       

vbo = 10.85  #  velocity at burnout                                               

gamma = 0 * np.pi / 180  #  angle in radians of the flight path                   

vx = vbo * (np.sin(gamma) * np.cos(nu) - np.cos(gamma) * np.sin(nu))
#  velocity of the bo in the x direction                                          
vy = vbo * (np.sin(gamma) * np.sin(nu) + np.cos(gamma) * np.cos(nu))
#  velocity of the bo in the y direction                                          

xrel = (re + 300.0) * np.cos(nu) - pi2 * r12
#  spacecraft x location relative to the earth         
yrel = (re + 300.0) * np.sin(nu)

#  r0 = [xrel, yrel, 0]                                                           
#  v0 = [vx, vy, 0]                                                               
u0 = [xrel, yrel, 0, vx, vy, 0]


def deriv(u, dt):
    n1 = -((mue * (u[0] + pi2 * r12) / np.sqrt((u[0] + pi2 * r12) ** 2
                                               + u[1] ** 2) ** 3)
        - (mum * (u[0] - pi1 * r12) / np.sqrt((u[0] - pi1 * r12) ** 2
                                              + u[1] ** 2) ** 3))
    n2 = -((mue * u[1] / np.sqrt((u[0] + pi2 * r12) ** 2 + u[1] ** 2) ** 3)
        - (mum * u[1] / np.sqrt((u[0] - pi1 * r12) ** 2 + u[1] ** 2) ** 3))
    return [u[3],  #  dotu[0] = u[3]                                              
            u[4],  #  dotu[1] = u[4]                                              
            u[5],  #  dotu[2] = u[5]                                              
            2 * omega * u[5] + omega ** 2 * u[0] + n1,  #  dotu[3] = that         
            omega ** 2 * u[1] - 2 * omega * u[4] + n2,  #  dotu[4] = that         
            0]  #  dotu[5] = 0                                                    


dt = np.arange(0.0, 320000.0, 1)  #  200000 secs to run the simulation            
u = odeint(deriv, u0, dt)
x, y, z, x2, y2, z2 = u.T

fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')
ax.plot(x, y, z)
plt.show()

Answer 1

您可以在plt.show()之前添加以下代码来绘制球体：

phi = np.linspace(0, 2 * np.pi, 100)
theta = np.linspace(0, np.pi, 100)
xm = rm * np.outer(np.cos(phi), np.sin(theta)) + r12
ym = rm * np.outer(np.sin(phi), np.sin(theta))
zm = rm * np.outer(np.ones(np.size(phi)), np.cos(theta))
ax.plot_surface(xm, ym, zm)

但是，您的月亮看起来会被拉长，因为所有轴的比例都不相同。为了改变轴的比例，你可以添加类似

ax.auto_scale_xyz([-50000, 400000], [0, 160000], [-130000, 130000])

在plt.show() 之前。结果仍然不完全正确，但我让您自己尝试以获得更好的结果 - 我只是选择了一些使其看起来更好的数字。

Answer 2

球体的所有代码都在这里：

http://matplotlib.org/examples/mplot3d/surface3d_demo2.html

从那里你只需要向你想要的任何方向移动，并将 10 更改为你想要的任何半径。