Cosmic Velocity: A Journey Through the Universe
From planetary orbits to the movement of galaxies, cosmic speeds are now clearer.
The universe is a stage of perpetual motion. From the planets orbiting stars to galaxies crossing intergalactic space, nothing is static. Everything, from the smallest to the most colossal, moves at impressive speeds, some of which are as difficult to imagine as they are to measure. These dynamics are not only essential for understanding the structure of the cosmos, but they also reveal the fundamental forces that govern it, such as gravity and the expansion of space.
To tackle this challenge of scale and magnitude, a system that allows for comparing these speeds in a more accessible way is necessary. For this reason, I proposed the unit EVE (Earth Escape Velocity). This measure takes as reference the minimum speed required to overcome Earth’s gravitational pull, which is 11.2 km/s. By using EVE as a metric, cosmic speeds can be expressed in terms that are more intuitive and manageable for those seeking to understand the movements of the universe from a practical perspective.
Planetary Orbits in EVE
In the Solar System, planets present orbital speeds that decrease as their distance from the Sun increases, a direct reflection of how gravity regulates their movements. By expressing these speeds in EVE units, a more intuitive comparative scale is obtained:
- Mercury: 4.27 EVE
- Venus: 3.13 EVE
- Earth: 2.66 EVE
- Mars: 2.15 EVE
- Jupiter: 1.17 EVE
- Saturn: 0.86 EVE
- Uranus: 0.61 EVE
- Neptune: 0.49 EVE
The decrease in orbital speed with distance from the Sun is a direct consequence of the nature of gravity. According to Kepler’s laws and Newton’s universal law of gravitation, the gravitational force between two bodies decreases with the square of the distance between them. In the case of the Solar System, this decreasing force means that more distant planets experience less gravitational attraction from the Sun, which allows them to maintain stable orbits at slower speeds.
The Sun and Its Movement
The Sun is also in constant motion. It travels at a speed of 230 km/s, which is equivalent to 20.54 EVE. This figure, impressive in itself, becomes even more significant when understanding that it represents its trajectory relative to nearby stars, within a vast galactic neighborhood.
This movement is part of a much larger cycle: the Sun’s orbit around the center of the Milky Way. This journey, known as a galactic year, takes approximately 225 million years to complete. During this time, the Sun drags with it all the planets, asteroids, and comets of the Solar System. This galactic rhythm not only reflects our position within the galaxy but also underscores that we are immersed in a dynamic and ever-changing cosmos.
The Milky Way and the Great Attractor
On even larger scales, the Milky Way, our galaxy, reveals impressive speeds that challenge our understanding. As it moves through the cosmos, the Milky Way does not only experience local displacement. Compared to the cosmic microwave background (CMB), the remnant radiation from the Big Bang, the galaxy moves at a speed of 552 km/s, equivalent to 49 EVE. This speed, though astonishing, reflects only one aspect of the cosmic dynamism surrounding us.
The most surprising part is that the Milky Way does not move randomly. Its motion is driven by an enormous gravitational force from a massive galaxy cluster known as the Great Attractor. This cosmic region, located toward the Centaurus constellation, exerts such powerful gravitational attraction that the Milky Way is moving toward it at an even greater speed: 630 km/s, or 56 EVE. This movement highlights the intense interaction between galaxies in the universe and how large-scale gravitational forces govern the motion of cosmic structures.
Other Interesting Speeds Beyond the Solar System
Below are some other significant speeds. These figures offer a clearer view of the magnitude of cosmic movements, from our closest stellar neighbor to galactic collisions and the large-scale movements of galaxy groups.
- Alpha Centauri, our neighboring star system: 2.68 EVE (30 km/s)
- The future collision between the Milky Way and Andromeda: 9.82 EVE (110 km/s)
- The Local Group of galaxies toward the Virgo Cluster: 55.36 EVE (620 km/s)
With the EVE unit, cosmic speeds become more accessible and easier to compare. From the rapid orbits of planets in the Solar System to the stunning velocities of galaxies in the universe, this unit offers a clearer perspective on astronomical movements. The EVE unit helps us better understand the dynamism of the cosmos and put into context the vastness of our cosmic environment, allowing us to appreciate how small we are compared to cosmic scales.
