What is the Difference Between Solar System and Galaxy

The main difference between solar system and galaxy is that the solar system is based around a single star, whereas a galaxy contains millions-trillions of stars, including planets going around them.  

Solar systems and galaxies are two types of systems in the universe. Generally, solar systems are the smallest systems, while the galaxy is larger than a solar system.

Key Areas Covered

1. What is Solar System
     – Definition, Structure, Importance
2. What is Galaxy
     – Definition, Structure, Importance
3. Similarities Between Solar System and Galaxy
     – Outline of Common Features
4. Difference Between Solar System and Galaxy
     – Comparison of Key Differences

Key Terms

Galaxy, Solar System

What is Solar System

The solar system is a gravitationally bound system of the Sun. It is 4.6 billion years old. A giant, interstellar molecular cloud underwent a gravitational collapse in order to form the solar system. The solar system contains a star orbited by planets. In our solar system, the Sun takes the vast majority of the system’s mass (around 99.86%), while the planet Jupiter takes the highest mass among other planets. The Sun also has eight planets orbiting around it. They include Mercury, Venus, Earth, Mass, Jupiter, Saturn, Uranus, and Neptune. Among them, Venus, Mercury, Earth, and Mass are terrestrial planets containing rocks and metal.

Figure 1: Solar System      

Furthermore, there are four other planets that are larger than terrestrial planets. Jupiter and Saturn mainly contain gases such as hydrogen and helium. In contrast, Uranus and Neptune contain mainly ice. All eight planets have nearly circular orbitals around the sun. Moreover, the orbit of Earth is the ecliptic. Apart from that, our solar system contains six dwarf planets. The moons are the smaller bodies orbiting around planets. The two largest moons include Jupiter’s moon Ganymede and Saturn’s moon Titan.    

What is Galaxy

A galaxy is a system of gas, dust, billions of stars, and their solar systems. Therefore, a galaxy contains stars, interstellar gases, stellar remnants, dust, dark matter, etc. All these things are bound together by gravity. Generally, a galaxy contains 100 million stars. The largest galaxy contains 100 trillion stars. Meanwhile, galaxies’ morphology can be either spiral, elliptical, or irregular. Our galaxy is also known as the Milky Way.

Figure 2: Galaxy

Moreover, most of the mass of a galaxy occurs in the dark matter. In addition, galaxies contain supermassive black holes in their center. The central black hole of our galaxy has a mass four million times greater than the Sun. Black holes have gravitational effects. Dark matter is not visible as it does not emit radiation. Additionally, the spaces between galaxies are filled with tenuous gas. Its average density is less than one atom per cubic meter. Apart from that, the gravitational arrangement of most galaxies is in groups, clusters, and superclusters. The Milky Way is a local group.

Similarities Between Solar System and Galaxy

• Solar systems and galaxies are two types of things that occur in the universe.
• They contain stars and planets going around these stars.
• They do not expand.

Difference Between Solar System and Galaxy

Definition

The solar system refers to the collection of eight planets and their moons in orbit around the sun, together with smaller bodies in the form of asteroids, meteoroids, and comets, while a galaxy refers to a system of millions or billions of stars together with gas and dust, held together by gravitational attraction.

Size

The solar system contains one star and orbiting planets, while a galaxy contains a few thousand to trillions of stars. 

Age

The age of the solar system is about 4.6 billion years, while the age of the galaxy is about 500 million to 13.4 billion years.

Formation

The solar system forms from smaller pockets of gas within galaxies, while a galaxy forms from clouds of dust and gas that collide and merge.

Conclusion                                                     

In brief, the solar system and galaxy are two types of systems that occur in the universe. Generally, the solar system contains one star and its orbiting planets. The solar system is about 4.6 billion years. In addition, the solar system forms from smaller pockets of gas within the galaxy. In comparison, a galaxy contains a few thousand to trillions of stars. However, it is about 500 million to 13.4 billion years. Normally, a galaxy forms from clouds of dust and gas that collide and merge. In brief, the main difference between the solar system and the galaxy is their size.                                      

References:                

1. Our solar system. NASA. Retrieved May 3, 2023
2. What is a galaxy? NASA. Retrieved May 3, 2023

Image Courtesy:

1. “Solar System true color” By CactiStaccingCrane – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “NGC 4414 (NASA-med)” By The Hubble Heritage Team (AURA/STScI/NASA). – Own Work (Public Domain) via Commons Wikimedia