¿Por qué Venus y Mercurio se ven siempre cerca del horizonte?

Why are Venus and Mercury always seen near the horizon?

Venus and Mercury are always seen near the horizon due to their positions in the solar system and their orbits relative to Earth.

Venus and Mercury will be visible on the horizon

The planets Venus and Mercury begin to rise over the horizon during the evening. From about mid-June to the end of August, we can observe this event during the evenings just after sunset.

Venus and Mercury in the Solar System

  1. Internal Orbits : Venus and Mercury are the two planets closest to the Sun, with internal orbits relative to Earth. This means their orbits are closer to the Sun compared to Earth's.

  2. Distance from the Sun :

    • Mercury : Orbits at an average distance of about 0.39 astronomical units (AU) from the Sun.
    • Venus : Orbits at an average distance of approximately 0.72 AU from the Sun.
    • Earth : Orbits at an average distance of 1 AU from the Sun.
Buy MAK 127 telescope
Buy telescope

Relative Positions and Angle of Elongation

  1. Angle of Elongation : The angle of elongation is the angle between the Sun and a planet as seen from Earth. Since Venus and Mercury are closer to the Sun, their angle of elongation (maximum angular separation from the Sun) is limited.

    • Mercury : Its maximum elongation is approximately 28 degrees.
    • Venus : Its maximum elongation is approximately 47 degrees.

  2. Visibility :

    • Due to their limited elongations, Venus and Mercury never stray far from the Sun in the sky. This means they are only visible near the horizon, either shortly after sunset (when they are east of the Sun) or shortly before sunrise (when they are west of the Sun).
Buy telescope
Buy telescope

Horizon Effect

  1. Earth's Atmosphere : When we observe celestial objects near the horizon, we are looking through a greater amount of Earth's atmosphere than when we look at objects high in the sky. This can cause planets to appear brighter or to flicker due to atmospheric scattering.

  2. Visual Perspective : Due to the curvature of the Earth and the inclination of the planet's orbit, objects at positions of maximum elongation are still low in the sky from the perspective of the Earth-based observer.

Conclusion

The main reason why Venus and Mercury are always seen near the horizon is their proximity to the Sun and their internal orbits relative to Earth, which restrict their angles of elongation and, consequently, limit their visibility to twilight hours, near sunrise or sunset.

Back to blog