The Universe is a dynamic place where everything is in motion. From the smallest particles to the largest galaxies, nothing exists in isolation. Our Solar System, containing trillions of masses, is also part of this cosmic dance, orbiting around the galactic center. A popular video suggests that as the Solar System moves through the galaxy, it creates a vortex, dragging the planets behind it. However, the reality of our cosmic motion is far more complex and fascinating, governed by the principles of General Relativity. Our journey through the cosmos is shaped by gravity.
Planets orbiting the sun
Qualitative Accuracy vs. Quantitative Reality
The “vortex video” does capture some aspects of our Solar System’s motion correctly, showing that:
- The planets orbit the Sun roughly in the same plane.
- The Solar System moves through the galaxy at approximately a 60° angle relative to the galactic plane.
- The Sun appears to move up and down and in and out with respect to the rest of the galaxy as it revolves around the Milky Way.
While these points are qualitatively true, the video misrepresents the quantitative reality. Our motion is not a simple vortex but a complex interplay of various gravitational forces.
Our Cosmic Address: A Hierarchical Motion
We reside on Earth, a planet spinning on its axis and revolving around the Sun. The Sun, in turn, orbits the center of the Milky Way. Our Local Group, which includes the Milky Way, is being drawn towards Andromeda. The Local Group is moving within our cosmic supercluster, Laniakea, influenced by galactic groups, clusters, and cosmic voids. Laniakea itself resides within the KBC void amidst the large-scale structure of the Universe. Science has pieced together a comprehensive picture of our motion, allowing us to quantify our speed through space at various scales.
Local galaxy group
Quantifying Our Speed Through Space
While we perceive ourselves as stationary, Earth’s rotation propels us through space at approximately 1700 km/hr at the equator. However, this is a small contribution compared to other motions. Earth’s rotation contributes a speed of just 0.5 km/s.
Planets revolving around the Sun
Revolution Around the Sun
Earth orbits the Sun at around 30 km/s. Inner planets like Mercury and Venus move faster, while outer planets like Mars move slower. Mercury completes about four orbits for every one of Earth’s, while Neptune takes over 160 Earth orbits to complete a single revolution. Planets orbit in the plane of the Solar System and change their direction of motion continuously, with Earth returning almost to its starting point after 365 days.
Planetary orbits around the sun
Orbiting the Milky Way
The Sun is not stationary. Our Milky Way galaxy is massive and in motion. All its components move around inside, influenced by its net gravity. Located about 25,000 light-years from the galactic center, the Sun orbits in an ellipse, completing one revolution every 220–250 million years.
The Sun’s speed along this journey is estimated at 200–220 km/s, significantly larger than Earth’s rotation and revolution speeds. Throughout this motion, the planets remain in the same plane, without any “dragging” or vortex patterns.
The Milky Way Galaxy
Motion Within the Local Group
The galaxy itself is not stationary. It moves due to the gravitational attraction of overdense matter clumps and the lack of attraction from underdense regions. Within our Local Group, we are moving towards Andromeda at approximately 301 km/s relative to the Sun. Factoring in the Sun’s motion through the Milky Way, Andromeda and the Milky Way are approaching each other at around 109 km/s.
Andromeda Galaxy
Influence of Larger Structures
The Local Group is influenced by other galaxies and clusters of galaxies in our vicinity. These structures contribute an additional motion of approximately 300 km/s, but in a different direction than other motions.
Repulsion of Cosmic Voids
Cosmic voids, regions with less matter than average, exert a repulsive force. The attractive forces of overdense regions and the repulsive forces of underdense regions combine, contributing approximately 300 km/s each, resulting in a total effect approaching 600 km/s.
Virgo Supercluster
The gravitational effects on the Milky Way
The Total Motion
Combining all these motions, we find that we are moving through the Universe at 368 km/s, with a margin of error of about 30 km/s depending on the time of year. Measurements of the cosmic microwave background (CMB) confirm this, appearing hotter in the direction we are moving and colder in the opposite direction.
CMB
Ignoring Earth’s rotation and revolution, our Solar System moves relative to the CMB at 368 ± 2 km/s. Including the motion of the Local Group, the entire group moves at 627 ± 22 km/s relative to the CMB. The larger uncertainty is primarily due to the difficulty in measuring the Sun’s motion around the galactic center.
The Dipole Repeller
Conclusion: A Sum of Cosmic Motions
The journey of How The Solar System Travels Through The Galaxy isn’t a simple vortex. Our planet and all the planets orbit the Sun in a plane, and this entire plane moves in an elliptical orbit through the galaxy. Every star in the galaxy moves in an ellipse, causing us to periodically pass in and out of the galactic plane. The Milky Way within the Local Group, the Local Group in our Supercluster, and all of it with respect to the rest-frame of the Universe all contribute to our complex cosmic motion. Thanks to astronomy and astrophysics, we now understand, with remarkable precision, the intricate details of our journey through the cosmos.
