[Article déjà publié le 27 juin 2024]
Who says planetary alignment means at least three planets taken into account, including Earth. It is then enough to see two planets (or more) coming together in the sky at the same point or in the same restricted area.
To estimate the probability of this type of event, it is necessary to look back at the environment of the planets in the solar system. These evolve within a narrow band of the sky called the zodiac, the central line of which is none other than a large circle going around the sky and called the ecliptic.
However, this point of view remains purely earthly. In space, the circle is actually a plane, called the ecliptic, which the planets remain close to during their orbit around the Sun. To evaluate the position of the planets at each moment, they are marked by an ecliptic geocentric longitude and latitude.
A notable influence of planetary alignments on Earth?
The Earth-Sun-Moon alignment is the source of spectacular tides. So what about planets? In reality, the force of attraction of a celestial object decreases greatly with distance. The Sun, for example, exerts a force on the Earth that is less than that of the Moon.
Jupiter is the most massive planet in the solar system, reaching one thousandth of the solar mass, but is five times further from us. The tide due to the attraction exerted by the giant planet is thus limited to a rise in ocean levels of barely one millimeter. A planetary alignment therefore has no notable effect on the Earth.
The synodic period of the planets of the solar system
A true planetary alignment would see the points at the center of the different planets positioned along the same line at a given time. Of course, such an event is extremely rare, because the planets do not move in exactly the same plane. By seeing them as spheres rather than points, alignment becomes easier to achieve.
The synodic period represents the time taken to return to an Earth-planet-Sun configuration. It is 116 days for Mercury, 584 for Venus, 780 for Mars, 399 for Jupiter, 378 for Saturn, 370 for Uranus and 368 for Neptune.
Trading the alignment with a planetary grouping
To mathematically determine a general alignment, it is necessary to find the smallest common multiple of the synodic periods of each of the planets. Such an event should therefore take place every 147 billion years… Suffice to say that the chances of observing it are almost impossible!
It is better to look towards a planetary grouping in a given region of the sky. Thus, by combining the brightest stars visible to the naked eye within a radius of 10 degrees between -2000 and 2750, we come across nine dates. So make an appointment now for the next one: September 8, 2040!
With an unwavering passion for local news, Christopher leads our editorial team with integrity and dedication. With over 20 years’ experience, he is the backbone of Wouldsayso, ensuring that we stay true to our mission to inform.
