The planets move around the Sun in ellipses. The point of the orbit closest to the Sun is called perihelion, the most distant – aphelion. The vector drawn from some point of the ellipse to the focus is called the radius vector. The ratio of the distance between the foci to the length of the major axis of the ellipse is called the eccentricity.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.