Venus examples¶
Let’s define a small helper function:
def print_me(msg, val):
print("{}: {}".format(msg, val))
We can compute the geometric heliocentric position for a given epoch:
epoch = Epoch(1992, 12, 20.0)
lon, lat, r = Venus.geometric_heliocentric_position(epoch)
print_me("Geometric Heliocentric Longitude", round(lon.to_positive(), 5))
# Geometric Heliocentric Longitude: 26.11428
print_me("Geometric Heliocentric Latitude", round(lat, 4))
# Geometric Heliocentric Latitude: -2.6207
print_me("Radius vector", round(r, 6))
# Radius vector: 0.724603
Compute the geocentric position for 1992/12/20:
epoch = Epoch(1992, 12, 20.0)
ra, dec, elon = Venus.geocentric_position(epoch)
print_me("Right ascension", ra.ra_str(n_dec=1))
# Right ascension: 21h 4' 41.5''
print_me("Declination", dec.dms_str(n_dec=1))
# Declination: -18d 53' 16.8''
print_me("Elongation", elon.dms_str(n_dec=1))
# Elongation: 44d 46' 8.9''
Print mean orbital elements for Venus at 2065.6.24:
epoch = Epoch(2065, 6, 24.0)
l, a, e, i, ome, arg = Venus.orbital_elements_mean_equinox(epoch)
print_me("Mean longitude of the planet", round(l, 6))
# Mean longitude of the planet: 338.646306
print_me("Semimajor axis of the orbit (UA)", round(a, 8))
# Semimajor axis of the orbit (UA): 0.72332982
print_me("Eccentricity of the orbit", round(e, 7))
# Eccentricity of the orbit: 0.0067407
print_me("Inclination on plane of the ecliptic", round(i, 6))
# Inclination on plane of the ecliptic: 3.395319
print_me("Longitude of the ascending node", round(ome, 5))
# Longitude of the ascending node: 77.27012
print_me("Argument of the perihelion", round(arg, 6))
# Argument of the perihelion: 55.211257
Compute the time of the inferior conjunction close to 1882/12/1.0:
epoch = Epoch(1882, 12, 1.0)
conjunction = Venus.inferior_conjunction(epoch)
y, m, d = conjunction.get_date()
d = round(d, 4)
date = "{}/{}/{}".format(y, m, d)
print_me("Inferior conjunction date", date)
# Inferior conjunction date: 1882/12/6.6912
Compute the time of the superior conjunction close to 1993/10/1:
epoch = Epoch(1993, 10, 1.0)
conjunction = Venus.superior_conjunction(epoch)
y, m, d = conjunction.get_date()
d = round(d, 4)
date = "{}/{}/{}".format(y, m, d)
print_me("Superior conjunction date", date)
# Superior conjunction date: 1994/1/17.0465
Compute the time and angle of the western elongation close to 2019/1/1:
epoch = Epoch(2019, 1, 1.0)
time, elongation = Venus.western_elongation(epoch)
y, m, d = time.get_date()
d = round(d, 4)
date = "{}/{}/{}".format(y, m, d)
print_me("Western elongation date", date)
# Western elongation date: 2019/1/6.1895
elong = round(elongation, 4)
print_me("Maximum western elongation angle", elong)
# Maximum western elongation angle: 46.9571
Compute the time and angle of the eastern elongation close to 2019/10/1:
epoch = Epoch(2019, 10, 1.0)
time, elongation = Venus.eastern_elongation(epoch)
y, m, d = time.get_date()
d = round(d, 4)
date = "{}/{}/{}".format(y, m, d)
print_me("Eastern elongation date", date)
# Eastern elongation date: 2020/3/24.9179
elong = round(elongation, 4)
print_me("Maximum eastern elongation angle", elong)
# Maximum eastern elongation angle: 46.078
Compute the time of the station in longitude #1 close to 2018/12/1:
epoch = Epoch(2018, 12, 1.0)
sta1 = Venus.station_longitude_1(epoch)
y, m, d = sta1.get_date()
d = round(d, 4)
date = "{}/{}/{}".format(y, m, d)
print_me("Date of station in longitude #1", date)
# Date of station in longitude #1: 2018/10/5.7908
Compute the time of the station in longitude #2 close to 2018/12/1:
epoch = Epoch(2018, 12, 1.0)
sta2 = Venus.station_longitude_2(epoch)
y, m, d = sta2.get_date()
d = round(d, 4)
date = "{}/{}/{}".format(y, m, d)
print_me("Date of station in longitude #2", date)
# Date of station in longitude #2: 2018/11/16.439
Find the epoch of the Perihelion closer to 1978/10/15:
epoch = Epoch(1978, 10, 15.0)
e = Venus.perihelion_aphelion(epoch)
y, m, d, h, mi, s = e.get_full_date()
peri = str(y) + '/' + str(m) + '/' + str(d) + ' at ' + str(h) + ' hours'
print_me("The Perihelion closest to 1978/10/15 happened on", peri)
# The Perihelion closest to 1978/10/15 happened on: 1978/12/31 at 4 hours
Compute the time of passage through an ascending node:
epoch = Epoch(1979, 1, 1)
time, r = Venus.passage_nodes(epoch)
y, m, d = time.get_date()
d = round(d, 1)
print("Time of passage through ascending node: {}/{}/{}".format(y, m, d))
# Time of passage through ascending node: 1978/11/27.4
print("Radius vector at ascending node: {}".format(round(r, 4)))
# Radius vector at ascending node: 0.7205
Compute the (approximate) illuminated fraction of Venus disk for an Epoch:
epoch = Epoch(1992, 12, 20)
k = Venus.illuminated_fraction(epoch)
print_me("Approximate illuminated fraction of Venus", round(k, 2))
# Approximate illuminated fraction of Venus: 0.64
Compute the magnitude of Venus:
sun_dist = 0.724604
earth_dist = 0.910947
phase_angle = Angle(72.96)
m = Venus.magnitude(sun_dist, earth_dist, phase_angle)
print_me("Venus' magnitude", round(m, 1))
# Venus' magnitude: -3.8