Our Misleading Illustrations
We've all seen images of the solar system, but these depictions are often inaccurate. For illustrative purposes, these images exaggerate the sizes of planets and place them much closer than they truly are. In reality, all celestial bodies would appear too small, faint, and distant to be seen with the naked eye.
The True Scale of Our Solar System
If we were to view the solar system at its true scale, the sun would be the most easily observable object, but even it would be just a small, bright dot. Some larger planets might appear as stars, while others would be too faint to be seen.
Here’s what we see from Earth:
- We are looking at a vast part of the solar system when we gaze at the night sky.
- Planets and their orbits are proportional to the actual scale, with Earth’s orbit being closer to the sun compared to outer planets.
Image: An accurate depiction of the solar system with Earth’s orbit being close to the Sun in comparison to outer planets (Source: Spacecentre).
The Earth's Constant Motion
The planets in our solar system are constantly spinning on their axes and revolving around the sun. While we might feel stationary on Earth, the reality is very different. Earth rotates on its axis at a speed of approximately 1,700 kilometers per hour (0.5 km/s).
Earth’s Speed Around the Sun
This rotation speed seems impressive, but it’s dwarfed by Earth’s orbital speed around the sun. Earth travels around the sun at a breathtaking 30 km/s. It takes 365 days for Earth to complete a revolution, returning to its starting position, or at least near it, because the sun itself is not stationary.
Image: A realistic model of planetary orbits around the Sun, showcasing the planets’ movement across the galaxy in another direction, all within the same plane (Source: Rhys Taylor).
Our Galaxy's Motion
All celestial bodies, including stars, planets, gas clouds, dust particles, black holes, dark matter, and more, are constantly in motion within the Milky Way galaxy. As observed from Earth, located 25,000 light-years from the galactic center, the sun orbits the Milky Way in an elliptical path, completing a full revolution in 220-250 million years.
The Milky Way's Motion
The sun's velocity in this galactic journey is estimated to be 200-220 km/s, a speed far greater than Earth's rotation and its orbital speed around the sun. Despite this, all planets remain in the same plane, without any instances of them lagging behind or being pulled ahead as depicted in some illustrations.
The Expanding Universe
The Milky Way galaxy is not stationary, but constantly moving due to the gravitational influence of other cosmic objects. Within the Local Group, a collection of over 50 galaxies including the Milky Way, we can measure the Milky Way’s movement relative to the largest galaxy in the group, Andromeda.
Our Incredible Cosmic Journey
Andromeda is moving towards our sun at 301 km/s. When taking into account the sun’s movement within the Milky Way, Andromeda and our galaxy are moving towards each other at approximately 109 km/s.
Image: At the largest scale, not only Earth and the Sun are in motion, but the entire galaxy and the Local Group are moving due to unseen forces (Source: NASA/ ESA).
The Unseen Forces Shaping Our Universe
Even the Local Group, with its impressive size and multitude of galaxies, is not isolated. The pull of other galaxies and clusters around it adds another 300 km/s to our overall motion.
Adding all these movements together, Earth's rotation around its axis, Earth’s orbit around the Sun, the sun's movement around the Milky Way, the Milky Way's approach towards Andromeda, and the Local Group's motion influenced by surrounding regions, reveals our true speed within the universe. This speed is a staggering 368 km/s in a specific direction, with a variance of around 30 km/s depending on the time of year and Earth's rotation direction, according to Ethan Siegel, a Ph.D. astrophysicist at the University of Florida and author of the Starts With A Bang blog.
A Continuous Journey
Our planet, along with the other planets in the solar system, is moving on a plane that orbits in an elliptical path through the Milky Way.
As every star similar to our Sun in the galaxy also moves in an elliptical path, the solar system appears to move in and out of the Milky Way’s plane in cycles spanning tens of millions of years. This journey takes approximately 200-250 million years to complete a full revolution around the Milky Way.
Summary
We often see misleading illustrations of the solar system, misrepresenting the true scale and motion of celestial bodies. In reality, our solar system is a vast and constantly moving entity within the Milky Way galaxy. Our planet, along with the entire Milky Way, is journeying through the universe at incredible speeds, shaped by unseen forces and constantly evolving. Our true cosmic journey is far more dynamic and captivating than we often perceive.