The major difference between stars and planets is that Stars consist of plasma, a state of matter characterized by ionized atoms while Planets are composed of various materials such as rock, ice, gas, or water, determined by their composition and proximity to the star.
What are Stars?
Stars can be described as luminous spheres composed of plasma, held together by their gravitational force. Plasma, an extremely hot state of matter, forms the bulk of a star’s composition. These celestial bodies primarily consist of gases such as hydrogen, helium, and other lightweight elements.
Stars emerge from vast clouds of gas and dust in space, forming what are known as stellar nurseries commonly located within galaxies. Through the process of stellar formation, these colossal clouds collapse under their gravitational pull, initiating nuclear fusion in their cores, thereby commencing a star’s lifecycle.
Predominantly composed of hydrogen and helium, the lightest and most abundant elements in the cosmos, stars’ cores harbor extreme pressure and temperature conditions conducive to nuclear fusion. Within this environment, hydrogen atoms merge to create helium, releasing immense energy in the process. This energy generation sustains the luminous glow and thermal output that characterize a star.
Astronomers classify stars based on their size, temperature, and color, utilizing the Hertzsprung-Russell diagram as a framework. This classification system encompasses a spectrum of classes denoted as O, B, A, F, G, K, and M. O-type stars, the hottest and most radiant, contrast with M-type stars, which are cooler and less luminous.
What are Planets?
The term “planet” refers to celestial bodies orbiting a star in a defined path, known as an orbit. Planets are sufficiently massive to assume a spherical shape due to their gravitational pull but are not large enough to initiate nuclear reactions. Additionally, they have cleared their neighboring regions of other celestial bodies. Our solar system’s planets are categorized into two groups:
- Inner Planets: These planets orbit within the asteroid belt. They are relatively small in size and composed mainly of solid materials such as rocks and metals. The inner planets include Mercury, Venus, Earth, and Mars.
- Outer Planets: Outer planets orbit beyond the asteroid belt. They are larger in size compared to inner planets and often have rings surrounding them. Composed mainly of gases such as hydrogen and helium, the outer planets consist of Jupiter, Saturn, Uranus, and Neptune.
Stars vs Planets
The primary difference between stars and planets is given below:
| Stars | Planets | |
| Meaning | Astronomical objects emitting light through thermonuclear fusion at their core | Celestial objects with fixed orbits around a star |
| Light | Emit their own light. | Do not emit their own light. |
| Position | Changes but visibility may require substantial time. | Change position. |
| Size | Large | Small |
| Shape | Dot-shaped | Sphere-shaped |
| Temperature | High | Low |
| Number | One in a solar system. | Several in a solar system. |
| Twinkle | Twinkle | Do not twinkle. |
| Matter | Hydrogen, Helium, and other light elements. | Solid, liquid, gases, or a combination thereof. |