This astronomical event will be appreciated next January 21, 2025 and involves Mars, Jupiter, Uranus, Neptune, Venus and Saturn which will be observed in a single line facing north at sunset.
While it is common knowledge that Earth’s revolution around the Sun takes 365 days, this duration varies for other planets. Each follows its own path, known as the ecliptic, moving approximately in the same plane but at different speeds depending on their distance from the Sun. For instance, closer planets like Mercury and Venus move faster than distant ones like Saturn or Neptune.
This variation causes, very sporadically, a planetary alignment to occur. This means that some of the members of our solar system are grouped on the same side of our star to form an apparent straight line. It is important to understand that this alignment does not mean that they are physically close to each other, because there are millions of kilometers of distance between them.
According to Sandro Villanova, an Associate Researcher at the Center for Astrophysics and Associated Technologies (CATA), the rarity of this event lies in the number of planets involved. This time, six celestial bodies—Mars, Jupiter, Uranus, Neptune, Venus, and Saturn—will participate. Mercury will be on the opposite side of the Sun, not part of this planetary dance”.
“The planets orbit roughly in the same plane, and on that date, they will be located in the same part of the sky, aligned in a straight line tilted relative to the horizon. The tilt will depend on the observer’s latitude. The alignment will be visible in the evening along a band stretching from northeast to northwest as the Sun sets, lasting for several days, with January 21 being the most prominent. It will be observable from around 9:30 PM to 10:30 PM, depending on latitude. By early February, the Moon will also join this alignment,” explains Villanova, who is also the Director of the Astronomy Department at the University of Concepción.
Four of these planets (Mars, Jupiter, Venus, and Saturn) will be visible without special equipment. However, viewing Uranus and Neptune will require a telescope or binoculars. “These tools are also useful for observing planetary details, such as Jupiter’s moons, Saturn’s rings, or Venus’s phase,” adds Villanova.
It is worth noting that tall buildings or nearby mountains may obstruct the view, as some planets will be very low on the horizon. Smartphone apps like Starwalk or Stellarium can help locate the celestial bodies in the night sky.