def calculate_density_after_time(densities, time_0, time_explosion):
    """
    scale the density from an initial time of the model to the time of the explosion by ^-3

    Parameters:
    -----------

    densities: ~astropy.units.Quantity
        densities

    time_0: ~astropy.units.Quantity
        time of the model

    time_explosion: ~astropy.units.Quantity
        time to be scaled to

    Returns:
    --------

    scaled_density
    """

    return densities * (time_explosion / time_0) ** -3