How to plot celestial equator in galactic coordinates? Why does my plot appear "backwards"? I'm trying to plot celestial equator in galactic coordinates. Here is my code (based on this answer):
import matplotlib.pyplot as plt
import seaborn as sns; sns.set()
import numpy as np

from astropy.coordinates import SkyCoord
from astropy import units as u

ra_all = np.linspace(-180, 180, 100)
dec_0 = np.zeros(100)

# Transform equatorial coordinates to galactic
eq = SkyCoord(ra_all, dec_0, unit=u.deg)
gal = eq.galactic
l_plot, b_plot = gal.l.wrap_at('180d').radian, gal.b.radian


lon = np.linspace(0, 360, 100)
lat = np.zeros(100)

# Transform ecliptic coordinates to galactic
ecl = SkyCoord(lon, lat, unit=u.deg, frame='barycentricmeanecliptic')
ecl_gal = ecl.transform_to('galactic')
l_ecl_gal, b_ecl_gal = ecl_gal.l.wrap_at('180d').radian, ecl_gal.b.radian


plt.figure(figsize=(14,7))
plt.subplot(111, projection='aitoff')

plt.scatter(l_plot, b_plot, s=5, label='Celestial Equator')
plt.scatter(l_ecl_gal, b_ecl_gal, s=5, label='Eclptic')


plt.grid(True)
plt.legend(fontsize=16)

plt.show()


However, the map I drew seems to be flipped left to right compared to the one bellow (taken from here)


Question 1: Why does the result of my implementation appear to be the reverse of the other image? Do I have something wrong, or is this simply an issue of mapping the surface from the inside versus from the outside?
Question 2: What is the best way to change my code to make it draw galactic map in a conventional format?
Ok, community helped me to figure out that I faced the “mapping from the inside” issue (explained here). I'll use this answer to show my final code.
import numpy as np
from astropy.coordinates import SkyCoord
import astropy.units as u
import matplotlib.pyplot as plt
import seaborn as sns

sns.set()

def eq2gal(ra, dec):
    
    '''
    Transforms equatorial coordinates to galactic ones.
    Then prepares them for matplotlib aitoff projection. 
    '''
    
    eq = SkyCoord(ra, dec, unit=u.deg)
    gal = eq.galactic

    # Minus appears because of “mapping from the inside” issue
    l_gal, b_gal = -gal.l.wrap_at('180d').radian, gal.b.radian
    
    return l_gal, b_gal

def ecl2gal(lon_ecl, lat_ecl):
    
    '''
    Transforms ecliptic coordinates to galactic ones.
    Then prepares them for matplotlib aitoff projection.
    '''
    
    ecl = SkyCoord(lon_ecl, lat_ecl, unit=u.deg, frame='barycentricmeanecliptic')
    gal = ecl.transform_to('galactic')

    # Minus appears because of “mapping from the inside” issue
    l_gal, b_gal = -gal.l.wrap_at('180d').radian, gal.b.radian
    
    return l_gal, b_gal

# Equatorial plane
ra_all = np.linspace(-180, 180, 100)
dec_0 = np.zeros(100)

l_eq_gal, b_eq_gal = eq2gal(ra_all, dec_0)

# Ecliptic plane
lon_ecl = np.linspace(0, 360, 100)
lat_ecl = np.zeros(100)

l_ecl_gal, b_ecl_gal = ecl2gal(lon_ecl, lat_ecl)


plt.figure(figsize=(14,7))
plt.subplot(111, projection='aitoff')

plt.scatter(l_eq_gal, b_eq_gal, s=4, marker='v', label='Celestial Equator')
plt.scatter(l_ecl_gal, b_ecl_gal, s=4, marker='^', label='Eclptic')

# Essential thing is to rename RA axis ticks to transform them to conventional format
plt.xticks(ticks=np.radians([-150, -120, -90, -60, -30, 0, \
                             30, 60, 90, 120, 150]),
           labels=['150°', '120°', '90°', '60°', '30°', '0°', \
                   '330°', '300°', '270°', '240°', '210°'])


plt.grid(True)
plt.legend(fontsize=16, loc='lower center')

plt.title('Galactic', fontsize='16')

plt.show()