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Python solar system (a file in this repo https://github.com/chongchonghe/Python-solar-system )
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| #!/usr/bin/env python | |
| import numpy as np | |
| import matplotlib.pyplot as plt | |
| import matplotlib.animation as animation | |
| from astropy.time import Time | |
| from astroquery.jplhorizons import Horizons | |
| sim_start_date = "2018-01-01" # simulating a solar system starting from this date | |
| sim_duration = 2 * 365 # (int) simulation duration in days | |
| m_earth = 5.9722e24 / 1.98847e30 # Mass of Earth relative to mass of the sun | |
| m_moon = 7.3477e22 / 1.98847e30 | |
| class Object: # define the objects: the Sun, Earth, Mercury, etc | |
| def __init__(self, name, rad, color, r, v): | |
| self.name = name | |
| self.r = np.array(r, dtype=np.float) | |
| self.v = np.array(v, dtype=np.float) | |
| self.xs = [] | |
| self.ys = [] | |
| self.plot = ax.scatter(r[0], r[1], color=color, s=rad**2, edgecolors=None, zorder=10) | |
| self.line, = ax.plot([], [], color=color, linewidth=1.4) | |
| class SolarSystem: | |
| def __init__(self, thesun): | |
| self.thesun = thesun | |
| self.planets = [] | |
| self.time = None | |
| self.timestamp = ax.text(.03, .94, 'Date: ', color='w', transform=ax.transAxes, fontsize='x-large') | |
| def add_planet(self, planet): | |
| self.planets.append(planet) | |
| def evolve(self): # evolve the trajectories | |
| dt = 1.0 | |
| self.time += dt | |
| plots = [] | |
| lines = [] | |
| for p in self.planets: | |
| p.r += p.v * dt | |
| acc = -2.959e-4 * p.r / np.sum(p.r**2)**(3./2) # in units of AU/day^2 | |
| p.v += acc * dt | |
| p.xs.append(p.r[0]) | |
| p.ys.append(p.r[1]) | |
| p.plot.set_offsets(p.r[:2]) | |
| p.line.set_xdata(p.xs) | |
| p.line.set_ydata(p.ys) | |
| plots.append(p.plot) | |
| lines.append(p.line) | |
| self.timestamp.set_text('Date: ' + Time(self.time, format='jd', out_subfmt='date').iso) | |
| return plots + lines + [self.timestamp] | |
| plt.style.use('dark_background') | |
| fig = plt.figure(figsize=[6, 6]) | |
| ax = plt.axes([0., 0., 1., 1.], xlim=(-1.8, 1.8), ylim=(-1.8, 1.8)) | |
| ax.set_aspect('equal') | |
| ax.axis('off') | |
| ss = SolarSystem(Object("Sun", 28, 'red', [0, 0, 0], [0, 0, 0])) | |
| ss.time = Time(sim_start_date).jd | |
| colors = ['gray', 'orange', 'blue', 'chocolate'] | |
| sizes = [0.38, 0.95, 1., 0.53] | |
| names = ['Mercury', 'Venus', 'Earth', 'Mars'] | |
| texty = [.47, .73, 1, 1.5] | |
| for i, nasaid in enumerate([1, 2, 3, 4]): # The 1st, 2nd, 3rd, 4th planet in solar system | |
| obj = Horizons(id=nasaid, location="@sun", epochs=ss.time, id_type='id').vectors() | |
| ss.add_planet(Object(nasaid, 20 * sizes[i], colors[i], | |
| [np.double(obj[xi]) for xi in ['x', 'y', 'z']], | |
| [np.double(obj[vxi]) for vxi in ['vx', 'vy', 'vz']])) | |
| ax.text(0, - (texty[i] + 0.1), names[i], color=colors[i], zorder=1000, ha='center', fontsize='large') | |
| def animate(i): | |
| return ss.evolve() | |
| ani = animation.FuncAnimation(fig, animate, repeat=False, frames=sim_duration, blit=True, interval=20,) | |
| plt.show() | |
| # ani.save('solar_system_6in_150dpi.mp4', fps=60, dpi=150) |
Change this (line 56):
ss.time = Time(sim_start_date).jd
to this:
ss.time = Time(sim_start_date)
ss.time.format='jd'
And change this (line 47):
self.timestamp.set_text('Date: ' + Time(self.time, format='jd', out_subfmt='date').iso)
to this:
self.timestamp.set_text('Date: ' + self.time.iso)
That fixed the problem for me.
Yes that worked. Thanks!
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I got the following error message: