How to use the poliastro.bodies.Earth function in poliastro

    "attractor,location_str", [(None, "@ssb"), (Earth, "500@399"), (Venus, "500@299")]
)
@pytest.mark.parametrize(
    "plane,refplane_str",
    [(Planes.EARTH_EQUATOR, "earth"), (Planes.EARTH_ECLIPTIC, "ecliptic")],
)
def test_ephem_from_horizons_calls_horizons_with_correct_parameters(
    horizons_mock, attractor, location_str, plane, refplane_str
):
    unused_name = "Strange Object"
    unused_id_type = "id_type"
    epochs = Time(["2020-03-01 12:00:00"], scale="tdb")

    horizons_mock().vectors.return_value = {
        "x": [1] * u.au,
        "y": [0] * u.au,
        "z": [0] * u.au,

def test_propagate_instance():
    tof = 1.0 * u.min
    ss0 = Orbit.from_classical(
        Earth,
        1000 * u.km,
        0.75 * u.one,
        63.4 * u.deg,
        0 * u.deg,
        270 * u.deg,
        80 * u.deg,
    )
    C_D = 2.2 * u.one  # dimentionless (any value would do)
    A = ((np.pi / 4.0) * (u.m ** 2)).to(u.km ** 2)
    m = 100 * u.kg
    spacecraft = Spacecraft(A, C_D, m)
    earth_satellite = EarthSatellite(ss0, spacecraft)
    orbit_with_j2 = earth_satellite.propagate(tof=tof, gravity=EarthGravity.J2)
    orbit_without_perturbation = earth_satellite.propagate(tof)
    orbit_with_atmosphere_and_j2 = earth_satellite.propagate(
        tof=tof, gravity=EarthGravity.J2, atmosphere=COESA76()

H0=H0,
            rho0=rho0
        )          

    else:
        pass      

    

    print("")
    print("Positions and velocity vectors are:")
    #print(str(rr.x))
    #print([float(s) for s in re.findall(r'-?\d+\.?\d*',str(rr.x))])
    r=[[float(s) for s in re.findall(r'-?\d+\.?\d*',str(rr.x))][0],[float(s) for s in re.findall(r'-?\d+\.?\d*',str(rr.y))][0],[float(s) for s in re.findall(r'-?\d+\.?\d*',str(rr.z))][0]]* u.km
    v=[[float(s) for s in re.findall(r'-?\d+\.?\d*',str(rr.v_x))][0],[float(s) for s in re.findall(r'-?\d+\.?\d*',str(rr.v_y))][0],[float(s) for s in re.findall(r'-?\d+\.?\d*',str(rr.v_z))][0]]* u.km / u.s
    f_orbit= Orbit.from_vectors(Earth, r, v)
    print(r)
    print(v)
    #f_orbit.plot()
    print("")
    print("Orbital elements:")    
    print(f_orbit.classical())
    print("")
    #print("")
    #print(f_orbit.ecc)
    plotOrbit((f_orbit.a.value),(f_orbit.ecc.value),(f_orbit.inc.value),(f_orbit.raan.value),(f_orbit.argp.value),(f_orbit.nu.value))

"""Example data.

"""
from astropy import time, units as u

from poliastro.bodies import Earth, Sun
from poliastro.twobody import Orbit

iss = Orbit.from_vectors(
    Earth,
    [8.59072560e2, -4.13720368e3, 5.29556871e3] * u.km,
    [7.37289205, 2.08223573, 4.39999794e-1] * u.km / u.s,
    time.Time("2013-03-18 12:00", scale="utc"),
)
"""ISS orbit example

Taken from Plyades (c) 2012 Helge Eichhorn (MIT License)

"""

molniya = Orbit.from_classical(
    Earth, 26600 * u.km, 0.75 * u.one, 63.4 * u.deg, 0 * u.deg, 270 * u.deg, 80 * u.deg
)
"""Molniya orbit example"""

_r_a = Earth.R + 35950 * u.km

R = Earth.R.to(u.km).value
    k = Earth.k.to(u.km ** 3 / u.s ** 2).value
    #s0 = Orbit.from_classical(Earth, x[0] * u.km, x[1] * u.one, x[4] * u.deg, * u.deg, x[3] * u.deg, 0 * u.deg, epoch=Time(0, format='jd', scale='tdb'))

    #orbit = Orbit.circular(
    #    Earth, 250 * u.km, epoch=Time(0.0, format="jd", scale="tdb"))

    # parameters of a body
    C_D = 2.2  # dimentionless (any value would do)
    A = ((np.pi / 4.0) * (u.m ** 2)).to(u.km ** 2).value  # km^2
    m = 100  # kg
    B = C_D * A / m

    # parameters of the atmosphere
    rho0 = Earth.rho0.to(u.kg / u.km ** 3).value  # kg/km^3
    H0 = Earth.H0.to(u.km).value
    
    print("Use default constants or you want to customize?\n1.Default.\n2.Custom.")
    check=input()
    if(check=='1'):
        pass
    else:
        m=input("Enter mass of the body in kg:")
        R=input("Enter radius of earth in km:")
        C_D=input("Enter C_D(dimension):")
        H0=input("Enter atmospheric parameter H0:")
        #rho0=input("Enter atmospheric parameter rho0:")
        R=R*u.km
        H0=H0*u.km
        #rho0=rho0*(u.kg / u.km ** 3)

    datetimeFormat = '%Y-%m-%d %H:%M:%S.%f'

Parameters
        ----------
        orbit : Orbit
            Position and velocity of a body with respect to an attractor
            at a given time (epoch).
        spacecraft: Spacecraft

        Raises
        ------
        ValueError
            If the orbit's attractor is not Earth

        """

        if orbit.attractor is not Earth:
            raise ValueError("The attractor must be Earth")

        self._orbit = orbit  # type: Orbit
        self._spacecraft = spacecraft  # type: Spacecraft

[7.37289205, 2.08223573, 4.39999794e-1] * u.km / u.s,
    time.Time("2013-03-18 12:00", scale="utc"),
)
"""ISS orbit example

Taken from Plyades (c) 2012 Helge Eichhorn (MIT License)

"""

molniya = Orbit.from_classical(
    Earth, 26600 * u.km, 0.75 * u.one, 63.4 * u.deg, 0 * u.deg, 270 * u.deg, 80 * u.deg
)
"""Molniya orbit example"""

_r_a = Earth.R + 35950 * u.km
_r_p = Earth.R + 250 * u.km
_a = (_r_a + _r_p) / 2
soyuz_gto = Orbit.from_classical(
    Earth, _a, _r_a / _a - 1, 6 * u.deg, 188.5 * u.deg, 178 * u.deg, 0 * u.deg
)
"""Soyuz geostationary transfer orbit (GTO) example

Taken from Soyuz User's Manual, issue 2 revision 0

"""

churi = Orbit.from_classical(
    Sun,
    3.46250 * u.AU,
    0.64 * u.one,
    7.04 * u.deg,
    50.1350 * u.deg,