Are Stars Bigger Than Planets?

When it comes to learning about space, it quickly becomes apparent that there really is a lot to learn, and our basic understanding from movies, high school lessons, and pop culture often give conflicting and even totally inaccurate perspectives on the truth about space and the various bodies and phenomena that occupy it.

One of the most prominent and interesting of all the objects in space are stars, and they have been an object of fascination for human civilization since ancient times when various civilizations worshipped the sun as a God or used the stars to depict their pantheons as well as navigate. 

It’s amazing how little people really know about stars in the modern era, however, and interest in space has declined since the days of the space race and early shuttle programs.

While there is a resurgent interest in the wake of the success of SpaceX, and the purported plans for Mars colonization, many people still don’t understand the rudiments of stellar bodies and their relationship with planets. 

In this guide, we’re going to look at whether stars can be bigger than planets, and how the two objects relate to each other to give you a better understanding of scale and how these bodies interact in space.]

Are Stars Bigger Than Planets?

The question technically has two answers, both of which are correct. 

In terms of main-sequence stars which are still active and churning out a lot of heat, such as our sun, planets are often far smaller. Even Jupiter, the biggest planet in our solar system, doesn’t come close to the size or mass of the sun, which is why the sun is at the center of the solar system, its gravitational pull is stronger than any other object in the area so these other smaller planets and objects orbit around it.

However, as we will discuss later there are other types of stars some of which are much smaller and weaker.

The best example of this is a white dwarf. This is essentially the remains of a once-proud main-sequence star that has exhausted itself and is no longer capable of sustaining nuclear fusion. The process of a star shrinking to a white dwarf involves several complex phases, but essentially what happens is that the star sheds its outer layers due to the loss of energy that its shrinking size and gravitational causes. 

The white dwarf is all that remains of the core of the star that would’ve once blazed immensely hot and been far larger in size.

Some stars turn into black holes at the end of their life cycle, but several turn to white dwarfs, which are still giving off some heat and light but only produce a minuscule amount, and are only as big as the Earth in size.

This leads us to the fact that in this case, there are many planets capable of being larger than a white dwarf. Gas giants are some of the largest planets in the universe, and these are capable of being several times larger than the white dwarf star.

Aside from this, however, most stars, even red dwarfs, will be comparable in size or much larger than the biggest gas giants.

Scientists believe that gas giants themselves may have once had the potential to become stars but lacked sufficient mass and gravity to become stars, so it’s easy to see why they are so large and can compare to some of the smaller types of stars.

Are There Different Types Of Stars?

Believe it or not, yes! Stars are grouped into various categories based on their size, the heat they give off, and their age as well as other factors to help scientists track and monitor them, as well as study them and discover them.

There are 7 main types of stars. These are;

O-type stars – These are fairly rare blue-colored stars known for their massive size. 

B-type stars – These are slightly smaller than 0 type stars but still massive compared to the other star classifications.

A-type stars – A types are slightly smaller than B types but still extremely big and are typically white in color.

F-type stars – F-type stars are slightly smaller than A-type stars and are typically yellowish-white, and make up around 3% of all stars.

G-type stars – G-type stars are yellow to yellowish white and make up some 7 to 8 percent of all stars. Our own sun is a good example of a G-type main-sequence star, and they are known for their smaller size compared to most other types of stars.

K-type stars – K types are slightly smaller than G-type stars and are usually light orange, occurring with a frequency of around 12 percent.

M-type stars – These are the smallest stars and vastly more common making up around 76 percent of all stars. They are orangey-red and are typically very weak compared to other types of stars.

Are There Different Types Of Planets?

There are many different types of planets, from rocky worlds such as Venus, Mars, and Earth, to water planets and huge gas giants which are essentially massive balls of gas surrounding a much smaller core.

The biggest planets in the universe are gas giants, such as Jupiter and Saturn, and it’s believed that these planets may have had the potential to become stars in some cases.

Why Are Stars Bigger Than Planets?

Stars are bigger than planets because they have much more mass. Stars are extremely dense and formed of various tightly packed gases and material that was captured as the star was being born. The sheer mass of the star is what allows it to sustain nuclear fusion, which is the reaction that allows the star to give off the radiation, light, and heat that sustains life and lights up the night sky.

Planets are made up of far less mass, and this is the reason why planets are smaller and orbit around stars, as stars have far more mass and thus far stronger gravity than planets.

For a star to be able to function there is a minimum amount of mass it needs to have in order to support the various reactions and processes that allow it to exist, and this is often a far greater amount of mass than most planets have, which is why planets are almost always smaller than main-sequence stars.

Can Planets Turn Into Stars?

Technically it’s possible, as there is a theoretical process known as stellification, in which Jovian-class planets or brown dwarf stars could potentially be provided with the mass required to initiate the fusion process that stars rely on.

Jovian class planets and brown dwarfs do not have the mass required to sustain the temperatures and processes that make up a star, but the theory suggests that seeding these bodies with a black hole could lead to a chain reaction of processes that leads to enough mass and energy being created to kickstart a brand new nuclear fusion reaction that would mark the reignition of a star.

Do Stars Have More Gravity Than Planets?

Almost certainly yes, stars have more gravity than planets in almost all cases due to their sheer size and mass, and the necessity of stars to acquire these amounts of mass in order to exist.