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In February 2025, a stunning planetary alignment–also known as the planet parade–allowed observers to see seven planets in the night sky simultaneously: Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune. The excitement around this event was palpable, as stargazers eagerly anticipated the rare sight of multiple Solar System planets in one view.
Aside from being amazing to look at, planetary alignments such as these are important for scientific research. Curious as to why? Check out this gallery to find out more.
On February 28, seven planets were visible: Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune, producing a rare seven-planet alignment.
Planet alignments are rare, but they happen because the eight major planets of our solar system orbit the Sun on the same flat plane, but at different speeds.
This means that every now and again, multiple planets line up on the same side of the Sun. If they are not perfectly aligned, the planets appear in an arc.
For people interested in astronomy, planet alignments are a sight to behold. However, they also have scientific implications.
In 2019, for example, researchers suggested that planet alignments may have an impact on solar activity, due to the way they combine the planets’ tidal forces.
The tidal pull of an individual planet on the Sun is very small. When combined, however, researchers believe that their pull may cause small rotations within the Sun.
These rotations are referred to as Rossby waves, and we also see them on Earth, where they cause extreme weather events such as cyclones and anticyclones.
Some scientists believe that in the Sun, Rossby waves may provide an explanation for why the Sun works on an 11-year cycle that goes from peak activity to low activity.
However, not every expert is convinced by this hypothesis. Indeed, many believe that solar activity can be explained by processes in the Sun alone.
A less contentious implication of planetary alignments is that they can be used to visit multiple different planets in a relatively short period of time.
In general, reaching the outer planets with a spacecraft is difficult because they are so far away that they would take decades to reach.
In 1966, however, a NASA scientist worked out that a planetary alignment of Jupiter, Saturn, Uranus, and Neptune in 1977 would allow astronauts to visit all four planets in just 12 years.
Given that the same voyage would take 30 years if the planets were not aligned, NASA scientists seized on the opportunity.
In 1977, they launched the twin Voyager 1 and 2 spacecraft on a so-called "Grand Tour" of the outer solar system.
Voyager 2 was the most successful. It used the alignment to visit all four planets, and became the first spacecraft ever to visit Uranus and Neptune.
Planetary alignments are also useful for learning about what goes on outside of our own solar system. In particular, they help us discover exoplanets (a planet that orbits a star other than our Sun).
When an exoplanet passes in front of its star from our point of view, it dims the light of the star, allowing for the planet’s size and orbit to be discerned.
This method of discovering an exoplanet is called the transit method, and it has been used to discover many exoplanets in orbit around certain stars.
For example, it is thanks to the transit method that we know there are seven Earth-sized planets orbiting Trappist-1, a red dwarf star that is located 40 light-years from our planet.
Transits can also be used to study the atmosphere on the exoplanets themselves. Indeed, when a planet passes in front of a star, the star’s light goes through the planet.
Given that the molecules and atoms of different gases absorb the star’s light at different wavelengths, this allows for gases such as carbon dioxide and oxygen to be identified.
Indeed, scientists owe a lot of their atmospheric composition analyses and the learnings therefrom to planetary alignments.
Alignments on a much larger scale, namely the alignment of galaxies, can even help scientists learn about the early universe.
In general, it is very difficult to observe galaxies in the early universe because they are so faint and distant.
However, if a large galaxy, or even a cluster of galaxies, passes between us and a much more distant galaxy, its huge gravitational pull can magnify the light of the more distant object.
This process is called gravitational lensing, and it allows us to observe and study the farther away of the two galaxies.
The work on these huge alignments is done by telescopes such as the James Webb Space Telescope.
This telescope is used to observe and study distant stars and galaxies, such as Earendel, the furthest known star from planet Earth.
The light from Earendel came from the first billion years of the 13.7-billion-year history of the universe, and it was only visible thanks to gravitational lensing.
Sources: (BBC)
See also: Stellar spectacular: NASA photos that will make you feel small
What does it really mean when the planets align?
The scientific implications of this rare event
TRAVEL Science
In February 2025, a stunning planetary alignment–also known as the planet parade–allowed observers to see seven planets in the night sky simultaneously: Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune. The excitement around this event was palpable, as stargazers eagerly anticipated the rare sight of multiple Solar System planets in one view.
Aside from being amazing to look at, planetary alignments such as these are important for scientific research. Curious as to why? Check out this gallery to find out more.