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Can Planets Become Stars?

Can Planets Become Stars?

The vast universe we live in contains an array of celestial bodies, ranging from planets and stars to more exotic objects like black holes and neutron stars. One fascinating question that often arises is whether planets can transform into stars.

It is highly unlikely for planets to become stars due to the significant differences in their mass and composition, which are essential for the initiation of nuclear fusion. Brown dwarfs, on the other hand, are substellar objects that share characteristics of both planets and stars, occupying a transitional space between the two.

This article aims to explore the possibilities and limitations of such a transition, delving into the fundamental differences between planets and stars, the conditions required for a planet to ignite into a star, and the known examples of celestial objects that have undergone similar transformations.

Defining Planets And Stars

Before examining the feasibility of a planet becoming a star, it is crucial to understand the defining characteristics of these celestial bodies.


Planets are celestial bodies orbiting a star or stellar remnants that have sufficient mass for their self-gravity to overcome rigid body forces, resulting in a nearly spherical shape. Moreover, planets have cleared the neighborhood around their orbit of other debris or smaller objects.

However, they are not massive enough to initiate and sustain nuclear fusion in their cores.

Examples of planets in our solar system include Earth, Mars, and Jupiter.


Stars are massive celestial bodies that generate their own light and heat through nuclear fusion processes in their cores. They have several distinct characteristics. Firstly, stars possess enough mass to trigger nuclear fusion, primarily involving the fusion of hydrogen atoms into helium.

Additionally, the internal pressure of stars balances the force of gravity, resulting in a stable size and shape. Moreover, they emit electromagnetic radiation, including visible light, as a result of the energy produced by nuclear fusion.

The Sun, Proxima Centauri, and Sirius are examples of stars in our galaxy.

The Process Of Stellar Formation

Understanding how stars form is essential when considering the possibility of a planet becoming a star. Star formation occurs in vast, dense regions of interstellar gas and dust called molecular clouds. These clouds are primarily composed of hydrogen, with trace amounts of helium and other elements.

When a section of a molecular cloud collapses under its own gravity, a protostar forms. As the protostar continues to accumulate mass from its surroundings, it heats up and increases in density. Eventually, the core temperature and pressure become high enough to initiate nuclear fusion, marking the birth of a star.

Watch this video to learn about stars becoming planets:

Can Stars Become Planets?

The Conditions Needed For A Planet To Become A Star

For a planet to become a star, it would have to undergo several fundamental changes, including:

  1. A significant increase in mass to attain the conditions necessary for nuclear fusion.
  2. A rise in core temperature and pressure facilitates the fusion process.
  3. The ability to generate and sustain energy output through nuclear fusion.

These requirements present several challenges for a planet aspiring to become a star.

Mass And Composition

The most significant obstacle for a planet to overcome is attaining the mass required for nuclear fusion. Planets are typically not massive enough to generate the necessary core pressure and temperature to initiate fusion. For instance, Jupiter, the largest planet in our solar system, would need to be approximately 80 times more massive to sustain nuclear fusion in its core.

Moreover, the composition of a planet is also a critical factor. Planets are mainly composed of elements heavier than hydrogen and helium, which are the primary constituents of stars. A planet’s composition would have to change dramatically to resemble that of a star.

Core Temperature And Pressure

Even if a planet could accumulate enough mass, it would also need to attain the proper core temperature and pressure required for nuclear fusion. For a celestial body to achieve these conditions, it must have a high enough mass to generate the gravitational force necessary to compress its core. However, this mass threshold is significantly higher than the mass of most known planets.

Brown Dwarfs

While the transformation of a planet into a star is highly unlikely, there exist celestial objects that blur the line between planets and stars – brown dwarfs. Brown dwarfs are substellar objects that possess more mass than the most massive planets but are not massive enough to sustain hydrogen fusion in their cores. They are often referred to as “failed stars” since they were unable to reach the mass necessary to become full-fledged stars.

Formation Of Brown Dwarfs

Brown dwarfs form in a similar manner to stars through the gravitational collapse of a molecular cloud. However, their growth is stunted prematurely, preventing them from amassing enough mass to initiate nuclear fusion. Brown dwarfs can also form when a protostar is ejected from a star-forming region, halting its ability to accumulate mass.

Characteristics And Detection

Brown dwarfs are challenging to detect due to their low luminosity and temperatures, which range from 300 to 3,000 Kelvin. They are often discovered through infrared observations, as they emit most of their radiation in the infrared spectrum.

Brown dwarfs have masses between approximately 13 and 80 times that of Jupiter, which places them in the mass range between planets and stars. While brown dwarfs are not stars, their existence demonstrates that some celestial objects occupy a transitional space between planets and stars.


While the idea of a planet becoming a star seems intriguing, it is highly unlikely due to the significant differences between planets and stars. Planets lack the necessary mass and composition required for nuclear fusion to occur in their cores.

Brown dwarfs, on the other hand, occupy a transitional space between planets and stars, demonstrating that there exists a continuum of celestial objects in the universe.