Difference Between Stars and Planets

Difference Between Stars and Planets - A Complete Guide

Edited By Vishal kumar | Updated on Jul 02, 2025 05:00 PM IST

In this article, we are going to learn about stars, planets, how a planet differs from a star or star and planet difference, the difference between space and sky, the difference between space and universe and many more. When you look up high in the sky at night, you'll see trillions of shimmering dots, some of which are brighter, some of which are larger, and some of which twinkle.

This Story also Contains

Star
The Cycle of a Star's Life
Planets
Difference Between Space and Universe

Difference Between Stars and Planets - A Complete Guide

Star

A celestial body with its own light and energy is known as a star. A star is a massive, gleaming ball of heated gas made primarily of Hydrogen and Helium that have collided due to gravity. Heavy elements such as carbon, nitrogen, and oxygen are produced by stars. The visual aspect of the universe is shaped by star formation, which also supplies the locations for planets. Especially in the field of astronomy.

The Cycle of a Star's Life

Stars are born within dust clouds and are found across most galaxies. The Orion Nebula is a well-known example of such a dust cloud. In the blazons of spiral galaxies, stars develop as an impenetrable cloud of gas.

Under the influence of the star's gravity, individual hydrogen atoms descend with accretionary speed and energy into the cloud's centre. Deep within these clouds, slubs of sufficient mass form, causing the gas and dust to begin to collapse under their own gravitational force. The gas is heated by the increase in energy. The temperature rises to around 20 million degrees Fahrenheit after millions of years of this activity.

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The hydrogen within the star ignites and burns in a never-ending series of nuclear events at this temperature, and the material at the centre begins to heat up. The Sun, our nearest star, is so hot that a massive amount of hydrogen conducts a star-wide nuclear reaction, similar to that of a hydrogen bomb. Even though it is constantly bursting in a nuclear reaction, the Sun and other stars are so massive that the explosion will take billions of years to consume all of the star's fuel. The inward force of gravity balances the exterior pressure of the gas heated by fusion, leaving the star in hydrostatic equilibrium. By keeping the star's temperature constant, this hydrostatic equilibrium remains balanced during the majority of the star's life. From birth to death, and all the stages in between, the life cycle of any star would take billions of years. That's why, to these goliaths, a human morsel of a blink of an eye doesn't seem to change anything.

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Planets

A planet is a celestial body that orbits the Sun and has sufficient mass for itself gravity to overcome rigid body forces, causing it to assume a hydrostatic equilibrium, making it round. Planets are smaller than stars.

A planet is a huge astronomical body that revolves in fixed orbits around the sun. Planets do not emit their natural light, but rather reflect the light of the sun. Planets, like stars, do not twinkle because they are considerably closer to us. The Earth is also a planet, and it is the only place in the cosmos where we know of life.

Types of Planets

Planets can be categorized into two types:
Inner Planets: The inner planets, also referred to as terrestrial planets, are those whose orbits are situated within the asteroid belt. These planets are relatively smaller in size and predominantly composed of solid elements such as rocks and metals. The inner planets in our solar system consist of Mercury, Venus, Earth, and Mars.

Outer Planets: The outer planets, conversely, have orbits that extend beyond the asteroid belt. These planets are notably larger in size compared to their inner counterparts and are characterized by the presence of rings. They are primarily composed of gases like hydrogen and helium. The outer planets in our solar system include Jupiter, Saturn, Uranus, and Neptune.

How Does a Planet Differ from a Star?

Understanding how a planet differs from a star is fundamental in astronomy. Here’s a quick breakdown of what is the difference between a star and a planet.

Stars	Planets
The most well-known astronomical objects are stars, which are the most basic building pieces of galaxies.	In comparison, the planet is a massive natural body that revolves around the Sun or a star and does not emit energy from nuclear fusion events.
Thermonuclear fusion, which occurs at the centre of stars, produces their own light.	Planets don't have their own light, thus they reflect the Sun's.
Because of the great distance between the stars, their positions vary, and this can be seen after a long period.	Planets have a tendency to shift positions as they orbit the Sun.
Greater in size	Smaller in size
They have a dot-like shape	They have a similar structure
A star is a massive gaseous object with a very high temperature.	Their temperature is low
Because of air refraction, they glitter.	They are not twinkling.
Hydrogen, helium, and other light elements make up this substance.	Solids, liquids, or gases, or a combination of these three.
Stars travel in their own orbits, each with a substantial distance between them, and their motion can be observed after a long period.	Planets follow a specific course around the Sun as they orbit the Sun. Orbit is the name given to this journey (Elliptical orbit).
In the solar system, there is only one star, but there are trillions of stars in the galaxy.	In the solar system, there are eight planets.

This table highlights the difference between a star and a planet and answers questions like how a planet differs from a star and how a planet is different from a star by providing clear contrasts between these celestial objects.

Difference Between Space and Universe

Space	Universe
The void that lies between celestial objects is referred to as space.	The term "universe" encompasses all physical matter and energy, as well as solar systems, planets, galaxies, and all the contents of space.
Space does not include celestial objects; only the space between them is included.	All heavenly objects are included in the universe.
Magnetic fields, electromagnetic radiation, neutrinos, dust, and cosmic rays are all present in space.	Planets, stars, galaxies, and space make up the universe.

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Frequently Asked Questions (FAQs)

1. What do you mean by Star ?

A celestial body with its own light and energy is known as a star.

A star is a massive, gleaming ball of heated gas made primarily of Hydrogen and Helium.

2. What do you mean by Planets ?

A planet is a celestial body that orbits the Sun and has sufficient mass for its self-gravity to overcome rigid body forces, causing it to assume a hydrostatic equilibrium, making it round.

3. Out of star and planet which one have bigger size?

Star

4. What is the total number of planet present in the solar planet?

Eight

5. Distinguish between stars and planets or What is the difference between a star and a planet

Stars	Planets
The most well-known astronomical objects are stars, which are the most basic building pieces of galaxies.	In comparison, the planet is a massive natural body that revolves around the Sun or a star and does not emit energy from nuclear fusion events.
Thermonuclear fusion, which occurs at the centre of stars, produces their own light.	Planets don't have their own light, thus they reflect the Sun's.
Because of the great distance between the stars, their positions vary, and this can be seen after a long period.	Planets have a tendency to shift positions as they orbit the Sun.
Greater in size	Smaller in size
They have dot like shape	They have round like structure
A star is a massive gaseous object with a very high temperature.	There temperature is low
Because of air refraction, they glitter.	They are not twinkling.
Hydrogen, helium, and other light elements make up this substance.	Solids, liquids, or gases, or a combination of these three.
Stars travel in their own orbits, each with a substantial distance between them, and their motion can be observed after a long period.	Planets follow a specific course around the Sun as they orbit the Sun. Orbit is the name given to this journey (Elliptical orbit).
In the solar system, there is only one star, but there are trillions of stars in the galaxy.	In the solar system, there are eight planets.

6. Can planets exist without a star?

Yes, planets can exist without orbiting a star. These are called "rogue planets" or "free-floating planets." They were likely ejected from their original star systems due to gravitational interactions. These planets drift through space alone and are very difficult to detect due to their lack of a nearby light source.

7. Can planets have moons, and can stars have planets?

Planets can indeed have moons, which are natural satellites orbiting them. In our solar system, many planets have moons, with Jupiter having the most (79 known moons). Stars can have planets orbiting them, forming a planetary system. Our Sun, for example, has eight known planets in its system. Many other stars have been discovered to have exoplanets orbiting them as well.

8. How do the lifespans of stars and planets compare?

Stars and planets have vastly different lifespans. Stars live for millions to billions of years, depending on their mass, with smaller stars living longer. Planets, however, can potentially exist for much longer. They may survive the death of their parent star and continue orbiting the stellar remnant or become rogue planets. Earth, for example, is about 4.5 billion years old and is expected to remain habitable for another billion years or so, while our Sun is only halfway through its expected 10-billion-year lifespan.

9. How does gravity differ between stars and planets?

Gravity on the surface of a star is typically much stronger than on a planet due to the star's much greater mass. However, the exact strength depends on the object's mass and radius. Some dense planets or stellar remnants like neutron stars can have stronger surface gravity than some stars. The Sun's surface gravity is about 28 times Earth's, but a neutron star's gravity can be billions of times stronger than Earth's.

10. Why don't we see planets during the day like we see the Sun?

We don't see planets during the day for the same reason we don't see other stars - the Sun's brightness overwhelms their relatively faint light. The Sun is much closer to Earth than any other star or planet, making it appear much brighter. Planets are visible at night because they reflect sunlight and there's no competing light from the Sun. Venus and Jupiter can occasionally be seen during twilight or even in a clear daytime sky, but this is rare and requires excellent viewing conditions.

11. Do stars and planets have the same shape?

No, stars and planets have different shapes. Stars are generally spherical due to their immense gravity pulling matter inward equally from all directions. Planets, while also mostly spherical, can have slight deviations from a perfect sphere due to factors like rotation speed and internal composition. Gas giant planets can even appear visibly oblate (flattened at the poles) due to their rapid rotation.

12. Can planets become stars?

Planets cannot become stars under normal circumstances. To become a star, an object needs to have enough mass (at least 75 times the mass of Jupiter) to initiate and sustain nuclear fusion in its core. Even the largest known planets are far below this threshold. However, very large gas giants are sometimes called "failed stars" or brown dwarfs, as they occupy a middle ground between planets and stars.

13. Why do planets orbit stars, but stars don't orbit planets?

Planets orbit stars due to the vast difference in mass between them. Stars are much more massive, creating a strong gravitational field that attracts and holds planets in orbit. While planets do exert a small gravitational pull on their stars, it's not enough to cause the star to orbit. Instead, stars and planets orbit a common center of mass, which is typically very close to or inside the star due to its much larger mass.

14. Why are stars much hotter than planets?

Stars are much hotter than planets because they generate energy through nuclear fusion in their cores. This process releases enormous amounts of energy, heating the star to temperatures of thousands or millions of degrees. Planets, on the other hand, only receive heat from their parent star and don't have internal fusion reactions, resulting in much lower temperatures.

15. Do stars and planets have atmospheres?

Both stars and planets can have atmospheres, but they are very different in composition and behavior. Star atmospheres are extremely hot, consisting mainly of hydrogen and helium plasma. Planet atmospheres vary widely, from the thick, carbon dioxide-rich atmosphere of Venus to the thin, mostly nitrogen atmosphere of Mars. Some planets, like Mercury, have virtually no atmosphere at all.

16. How do the sizes of stars compare to planets?

Stars are generally much larger than planets. Our Sun, an average-sized star, has a diameter about 109 times that of Earth. Even the largest known planet, Jupiter, is tiny compared to most stars. However, there is some overlap between the smallest stars (red dwarfs) and the largest gas giant planets in terms of physical size, though stars are always much more massive.

17. Why do stars appear in different colors, while planets usually look white?

Stars appear in different colors due to their surface temperatures. Hotter stars appear blue or white, while cooler stars appear orange or red. This is related to black-body radiation. Planets, however, primarily reflect light from their star, which is often a mix of all visible wavelengths, resulting in a white appearance. Some planets may have a slight color due to their atmospheric composition or surface features, but this is usually subtle when viewed from Earth.

18. What is the main difference between stars and planets?

The main difference is that stars produce their own light through nuclear fusion, while planets only reflect light from stars. Stars are massive, hot balls of gas, primarily hydrogen and helium, that generate energy in their cores. Planets are smaller, cooler bodies that orbit around stars and are made of rock, gas, or a combination of both.

19. Why do stars appear to twinkle, but planets don't?

Stars appear to twinkle due to atmospheric turbulence distorting their light as it travels through Earth's atmosphere. Planets don't twinkle because they appear as small discs rather than point sources of light, so the atmospheric effects average out across their surface. This difference in appearance can help distinguish stars from planets in the night sky.

20. How can you tell the difference between a star and a planet with the naked eye?

There are several ways to distinguish stars from planets with the naked eye:

21. How do the compositions of stars and planets differ?

Stars are primarily composed of hydrogen and helium, the two lightest elements, with small amounts of heavier elements. Planets, on the other hand, have a wide range of compositions. Terrestrial planets like Earth are made mostly of rock and metal, while gas giants like Jupiter are primarily hydrogen and helium. Ice giants like Uranus contain significant amounts of "ices" such as water, ammonia, and methane.

22. How does the concept of "habitable zone" apply to stars and planets?

The habitable zone, often called the "Goldilocks zone," is a concept that applies to the relationship between stars and planets. It refers to the range of distances from a star where conditions on an orbiting planet might be suitable for liquid water on its surface. This zone depends on the star's size and temperature - larger, hotter stars have habitable zones farther out than smaller, cooler stars. Planets within this zone are considered more likely to support life as we know it.

23. How do the rotation periods of stars and planets compare?

The rotation periods of stars and planets can vary widely:

24. How do stars and planets move differently in the night sky?

Stars appear to move across the night sky in a fixed pattern due to Earth's rotation. They maintain their positions relative to each other, which is why we see the same constellations year after year. Planets, however, move independently against the background of stars. They follow paths near the ecliptic (the apparent path of the Sun across the sky) and can be seen to change position relative to the stars over weeks or months. This independent motion is why planets were named "wanderers" by ancient astronomers.

25. Can stars and planets both have magnetic fields?

Yes, both stars and planets can have magnetic fields, but they are generated differently. Stars create magnetic fields through the movement of charged particles in their plasma, often resulting in complex and dynamic field structures. Planets typically generate magnetic fields through the movement of molten material in their cores, creating a dynamo effect. Not all planets have significant magnetic fields; Mars, for example, has only a weak field, while Jupiter's is extraordinarily strong.

26. Why do some planets have rings while stars don't?

Some planets, particularly gas giants like Saturn, have ring systems composed of ice, dust, and rock particles orbiting in a disc around the planet. These rings are held in place by the planet's gravity and are believed to form from debris of moons, comets, or asteroids that were broken apart by the planet's gravitational forces. Stars don't have ring systems because their intense heat and radiation would vaporize or push away any nearby small particles. Additionally, a star's gravity would likely incorporate any significant amount of orbiting material into the star itself or form it into planets.

27. How do stars and planets end their lives differently?

Stars and planets have very different end-of-life scenarios. Stars end their lives based on their mass:

28. Can stars capture planets, or can planets capture moons?

Both scenarios are possible, but capturing planets or moons is relatively rare:

29. How do stars and planets contribute to the formation of elements?

Stars and planets contribute to element formation in different ways:

30. Why do some stars pulsate, but planets don't?

Some stars pulsate due to internal processes related to their structure and energy generation:

31. How do binary star systems differ from star-planet systems?

Binary star systems and star-planet systems differ in several key ways:

32. How do stars and planets affect space-time differently?

Both stars and planets affect space-time through their gravity, as described by Einstein's theory of general relativity. However, the magnitude of this effect differs significantly:

33. Why can we see surface features on planets but not on stars?

We can see surface features on planets but not on stars for several reasons:

34. Can stars and planets both have storms or weather systems?

Both stars and planets can have storms and weather systems, but they are very different in nature:

35. How do stars and planets differ in their internal structure?

Stars and planets have fundamentally different internal structures: