def nearest_system(centre, systems):
    """
    Given a centre system, choose next nearest in systems.

    Returns:
        [dist_to_centre, System]
    """
    best = [centre.dist_to(systems[0]), systems[0]]
    for system in systems[1:]:
        dist = centre.dist_to(system)
        if dist < best[0]:
            best = [dist, system]

    return best