Stargazers are in for a spectacular celestial event on February 28, when all seven visible planets in our Solar System align in the night sky. This rare alignment, which includes Mercury joining the already-visible planets Venus, Mars, Jupiter, Saturn, Uranus, and Neptune, offers not only a visual treat but also scientific value.
During the months of January and February, six planets are visible from Earth, offering a planetary parade. However, the full alignment will only occur on February 28, weather permitting. As explained by Jenifer Millard, an astronomer at Fifth Star Labs, “There is something special about looking at the planets with your own eyes. Yes, you can go on Google and get a more spectacular view of all these planets. But when you’re looking at these objects, these are photons that have travelled millions or billions of miles through space to hit your retinas.” This alignment provides an opportunity to appreciate the vast distances that the light from these planets has traveled to reach us.
Although such alignments are visually captivating, the alignment of planets does not significantly impact Earth. As Millard notes, “it’s just happenstance that they happen to be in this position of their orbits.” Some scientists have speculated about the potential effects of planetary alignments on Earth, such as influencing solar activity. In 2019, physicist Frank Stefani proposed that the tidal forces of Venus, Earth, and Jupiter could combine to influence the Sun’s 11-year activity cycle, known as the solar cycle. However, other scientists, such as Robert Cameron from the Max Planck Institute, remain skeptical, pointing out that solar activity can be explained by internal processes within the Sun itself.
Despite the lack of evidence for direct impacts on Earth, planetary alignments do have practical uses in space exploration. Alignments enable spacecraft to travel more efficiently through the Solar System by using the gravitational pull of well-placed planets to slingshot them toward their destinations. A historic example of this occurred with NASA’s Voyager missions. In 1977, a rare alignment of the outermost planets—Jupiter, Saturn, Uranus, and Neptune—allowed Voyager 2 to visit all four planets in just 12 years, a feat that would have taken much longer without the alignment. Fran Bagenal, an astrophysicist on the Voyager team, explains, “If Voyager 2 had left in 1980, it would have taken until 2010 to get to Neptune.”
Planetary alignments also aid in the study of exoplanets—planets that orbit stars outside our Solar System. Astronomers use the transit method to detect these distant worlds. When an exoplanet passes in front of its host star from our viewpoint, the star’s light dims, revealing key information about the planet’s size and orbit. This method has allowed scientists to study the atmospheres of exoplanets in systems like TRAPPIST-1, a star system 40 light-years from Earth that features seven Earth-sized planets. As Jessie Christiansen from NASA’s Exoplanet Science Institute explains, “The vast majority of our atmospheric composition analysis is due to alignments.”
Alignments are also invaluable tools for studying the early Universe. Through gravitational lensing, a process in which the gravitational pull of a galaxy or cluster of galaxies magnifies the light from more distant objects, astronomers can observe far-off stars and galaxies. The James Webb Space Telescope uses this method to study stars like Earendel, the most distant known star, with light dating back to the first billion years of the Universe’s existence.
Beyond these practical applications, planetary alignments may also provide opportunities for more speculative scientific inquiries. In 2024, graduate student Nick Tusay at Pennsylvania State University used alignments of the planets in the TRAPPIST-1 system to search for any signals between the planets, similar to how humans send signals to Mars. While no signals were detected, the idea of extraterrestrial civilizations potentially using alignments to communicate is an intriguing possibility.
The February 28 planetary alignment serves as a reminder of the beauty and complexity of our Solar System and the broader Universe. Whether through practical space exploration, studying exoplanets, or merely gazing up at the night sky, these alignments allow us to better understand our place in the cosmos.
