What are Sunspots?

How Big is the Sun Compared to Earth? Facts About the Sun

Our Sun is a star at the center of our galaxy, and a very important source of energy, heat, and life for all living things here on Earth.

In this guide, we will discuss how big is the Sun compared to Earth, as well as other facts related to our Sun: like how far the Sun is from the earth, how hot the sun is, as well as other intriguing facts.

Let us begin answering the first question.

How Big Is The Sun Compared to Earth?

The short answer is, the Sun’s volume is as big as more than 1 million times that of the Earth, to be exact, 1,287,000 times bigger than our Earth.

The Sun has a diameter of 865,000 miles (or, 1,392,000 km), while the Earth’s diameter is only 7,918 miles or (12,742 km). So, diameter-wise, the Sun is nearly 109 times larger than our Earth. To put it into context, we can theoretically put 109 Earths side by side to match the Sun’s diameter.

The sun itself is almost a perfectly spherical object that is made of magnetic fields and hot plasma energy. It has a mass of 4.385 × 10^30 lbs or 1.9891 × 1030 kg, which is 330,000 times the Earth’s mass.

In fact, the Sun’s mass makes up almost the whole (99.98%) mass of our solar system. About three-quarters of the Sun’s mass is formed by hydrogen and the other quarter is mostly helium.

Only around 1.69% of the Sun’s mass consists of other elements like carbon, oxygen, neon, iron, and other materials. However, even 1.69% of the Sun’s mass is already 5,628 times the Earth’s mass.

Again, it would take almost 1.3 million Earths to fill the Sun’s whole volume, and so it is really a giant when compared to our Earth.

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How Far is The Sun From Earth

The Sun is located at the center of our solar system and all objects in our solar system (planets, asteroids, comets, and others) revolve around it at various distances.

With that being said, the Earth orbits the sun at an average distance of 92,955,807 miles (or,149,597,870 km). We say average, because the Earth’s orbit is not a perfect circle but elliptical (oval-shaped).

So, there’s a point during our Earth’s orbit when the distance is closest to the Sun (called perihelion) and there’s another point when the Earth is furthest to the sun or aphelion.

In 2020, the Perihelion happened on 5 January 2020, 14:47 and the Earth-Sun distance was 147,091,144 km. In 2021, the Perihelion will happen on 2 January 2021 20:50 and the distance between the Earth and Sun will be 147,093,163 km. As you can see, the perihelion distances might vary year by year.

Similarly, the Aphelion this year will happen on 4 July 2020 18:34 with a distance of 152,095,295 km. In 2021, it will happen on 6 July 2021 05:27 with a distance of 152,100,527 km.

In general, the perihelion is about 91 million miles (146 million km) and comes in early January, while the aphelion is about 94.5 million miles (152 million km) and comes in early July.

Mercury is the planet closest to the sun at our solar system and can be as close as 29 million miles (47 million km). Also, the distance between the Earth and The Sun is called an astronomical unit (or AU), and this measurement unit is used to measure distances throughout our solar system.

For example, Jupiter is, on average, 5.2 AU from the Sun, and Neptune is 30.07 AU from the Sun, on average.

The official standard of the astronomical unit (AU) since August 2012 is 149,597,870,700 meters, and the measurement is based on the speed of light, while a meter is defined as the distance traveled by light in a vacuum in 1 / 299,792,458 of a second.

However, for longer distances, we use light-years instead of AU, with light-years being the distance that light can travel in a vacuum in a standard Earth-year. One light-year is equal to 63,239 AU. For example, the nearest star, Proxima Centauri, is about 4.25 light-years away from Earth, or 268,770 AU.

What Is The Sun Made Of?

Just like any star (at least, any star in its prime age/condition), the sun consists of mainly hydrogen, and hydrogen atoms fusing by two by two into helium. This fusion (just like nuclear) produces a lot of energy, and this is how the Sun produces its heat.

Hydrogen makes around 71% of the Sun, and about 27% is Helium. Carbon, oxygen, and hydrogen make up 1.5%, while the other 0.5% is made up of other elements including iron, neon, silicon, and magnesium.

Below is a table listing the most common elements in our Sun:

Element NameAbundance (percentage of total mass)
Hydrogen71.0
Helium27.1
Oxygen0.97
Carbon0.40
Nitrogen0.096
Silicon0.099
Magnesium0.076
Neon0.058
Iron0.014
Sulfur0.040

A star’s characteristics and behavior are massively determined by its metal content. Even a very small difference in metals can completely change the behavior of a star, and this is called a star’s metallicity.

The more metallic a star is, the more it can absorb radiation, and the more opaque it will be. Also, how opaque a star is will affect its size, brightness, and temperature.

Metallicity will also tell you when the star will die: low-metallicity stars burn fuel faster than high-metallicity stars, and the Sun is only 1.3 percent metal. Meaning, the sun is not very opaque and might ‘die’ sooner than what we initially thought. However, it is still billions of years away, so we are fairly ‘safe’.

How Hot is Our Sun?

The average surface temperature of our Sun is around 5,778 Kelvins (10,000 Fahrenheit/ 5,600 Celsius), but the Sun itself is composed of three different layers with varying temperatures.

Our Sun, as discussed above, is mainly composed of gas which produces a massive amount of light and heat energy. Although the Sun is obviously the hottest object in our solar system, there are other stars that are tens of times hotter than the Sun.

However, answering the question ‘how hot is the Sun?’ is quite complex, since the Sun can vary greatly in temperatures depending on where it is measured:

The Core 

In the Sun’s core, the temperatures are estimated to be at 27 million degrees Fahrenheit / 15 million degrees Celsius (obviously there’s no way we can measure it directly). This immense temperature is created mainly due to two processes: gravitational attraction and nuclear fusion.

Nuclear fusion occurs when hydrogen atoms (which as we’ve discussed, makes 71% of the Sun) are compressed and fused to create helium. Nuclear fusion creates a massive amount of heat and light energy, which radiates outward to the Sun’s surface.

Remember that the Sun is very large, and the energy bounces around for up to a million years before it will move up to the upper layer of the Sun’s interior, called the convective zone. In this convective zone, temperatures can range between 3.5 million degrees F / 2 million degrees C.

While it has dropped significantly, it’s still a very massive heat creating large bubbles of hot plasma. In turn, this heat will produce ionized atoms that will move upward to the photosphere.

The Photosphere

 In the Sun’s photosphere, the temperatures dropped significantly to just about 10,000 degrees F or 5,500 degrees Celcius. In this region, the Sun’s radiation is detected as visible light. In the photosphere, we can also find sunspots, which are colder and darker compared to the surrounding area. Temperatures in sunspots can vary but can be as low as 7,300 degrees F  or 4,000 degrees C.

The Chromosphere 

The next layer of the Sun’s atmosphere is the chromosphere, which is much cooler than the photosphere at only 7,800 degrees Fahrenheit or around 4,320 degrees Celsius. The chromosphere also produces much weaker light compared to the photosphere.

Yet, during a total solar eclipse, the photosphere is blocked by the Moon, and so we can see the chromosphere as a red ring around the Sun (remember that viewing the chromosphere without protection can lead to eye damage, which can be permanent.)

The reason why the chromosphere appears red is still unknown, but many experts believe that it is caused by a huge presence of hydrogen.

The Corona/Crown 

In the Sun’s corona, the temperatures rise drastically ranging from 1.7 million degrees F / 1 million degrees Celsius and can reach more than 17 million degrees F / 10 million degrees C. The corona is much hotter than the layers, which is interesting since we expected the temperatures to be coolest in the outer layers.

How Heavy Is The Sun?

Answering this question is difficult since weight is relative to local gravity. The sun is obviously a source of its local gravity, and so we can’t weigh it with conventional means (not to mention, it’s so far away from Earth and so massive).

So, we can’t measure the true weight of the sun since we can’t sit the Sun upon something else.

However, the mass of the sun is 4,400,000,000,000,000,000,000,000,000,000 lbs or 1,989,000,000,000,000,000,000,000,000,000 kg (with 30 zeros).

So, as mentioned, our Sun is equivalent to 330,000 Earths, mass-wise. Comparatively, the Sun’s mass is 1,600 times that of Saturn, and 1,048 times Jupiter.

Weight vs Mass 

We have to differentiate between mass and true weight, which can be quite confusing for some who are not familiar with physics terms. So, let’s have a brief discussion about these two terms:

  • Mass: is the total amount of matter contained in an object.
  • Weight: is the total mass in relation to the local gravity (as discussed above) of the object, on which the object is being weighed

Why is the Sun’s weight so massive?

 The Sun’s size is obviously massive with a diameter of 865,000 miles (or, 1,392,000 km), which will translate into a circumference of around 2,7 million miles (the Earth, on the other hand, has a mere circumference of 25,000 miles).

However, not only the Sun is massive in size, it is also not hollow and as discussed above, is made of various layers:

  • The Corona
  • Transition Region
  • Chromosphere
  • Photosphere
  • Convective Zone
  • Radiative Zone
  • The Sun’s Core

The core makes up around a quarter of the star’s whole radius. It only makes up 2% of the Sun’s total volume but holds almost half of the Sun’s total mass. The radiative zone (which goes from 25% to 70% from the Sun’s radius.) makes 48% of the Sun’s mass while taking 32% of the sun’s volume.

So, the last 2% of its mass is taken by the convection zone (but it makes up 66% of the Sun’s volume). This is because the convection zone is made up of roiling convection cells of gas, so it’s pretty hollow.

How heavy is a human on the Sun’s surface? 

Since we know the gravity of the Sun, we can answer this question pretty accurately. Let’s assume that we are going to measure a human who weighs 150 lbs (68.0389 kg) on Earth.

The Sun has a relatively stronger gravitational pull than the Earth (due to its huge mass). So, all objects would weigh more on the Sun than they would on Earth. So, this person’s hypothetical weight on the Sun will be:

  • Weight on earth: 150 lbs (68.0389 kg)
  • Weight on the Sun: 3,947.7272 lbs (1790.658936761)

So, an object’s weight on the Sun is 26.31 times its weight on Earth.

Obviously this is all hypothetical. Not only we can’t put any object on the Sun’s surface without fully burning it first, but the Sun’s massive gravity pressure would also destroy the object completely.

What Is Solar Flare and What Causes It?

A solar flare is, in a nutshell, a giant explosion (flare) on the Sun’s surface. A solar flare is sudden and rapid, and can have an intense variation in brightness.

What actually causes a solar flare? The short answer is we don’t know exactly, and this is also why we can’t accurately predict them. It is still an active area of research and scientists are still working on this issue.

However, solar flares seem to be related to the Sun’s magnetic field. To be exact, a sudden release of the Sun’s magnetic energy. This caused enormous outbursts of energy and in a matter of minutes can spread along the Sun’s magnetic field lines.

This process releases a massive amount of energy that is equivalent to billions of nuclear explosions and thus will dramatically increase the temperature of the area on which the solar flare occurs.

A solar flare region is actually pretty huge, about the size of our Earth and the raised temperature can reach millions of degrees and can last for hours. In fact, the flare can become much hotter than the Sun’s core for a short period of time.

Again, since we don’t know much about how the Sun’s magnetic field works, the exact cause of these solar flares is still unknown.

What Are Sunspots?

Sunspots are temporary dark dots on the Sun’s photosphere.

Image source: https://spaceplace.nasa.gov/solar-activity/en/

They appear dark to us because sunspots are actually cooler than the surrounding areas. The photosphere, as discussed, has an average temperature of 10,000 degrees Fahrenheit or around 5,500 degrees Celsius.

On the other hand, the umbra, interior of a sunspot is around 1,600 degrees Fahrenheit cooler. This interior is surrounded by a lighter area, the penumbra, which is around 500 degrees Fahrenheit cooler than the surrounding photosphere.

Sunspots are cooler because of the Sun’s magnetic energy. Sunspots are areas of intense magnetic energy, and thus it pulls the flow of hot gasses from the Sun’s interior to its surface.

Remember that the Sun is not a solid object, but is a ball of continually circulating and rotating hot gases. Also, an important phenomenon to consider is that the Sun’s interior and exterior rotate separately: the exterior rotates quicker at the equator than the poles.

So, these messy movements distort the Sun’s magnetic energy and create areas of intense magnetism. In turn, they push back the hot gases beneath them while preventing the heat to rise to the Sun’s surface.

This phenomenon creates the sunspots, and at the same time, the hot gases are blocked by the sunspots and thus flow into the areas around them (which temporarily making these surrounding areas brighter and hotter than normal).

What Is The Nearest Star Besides Our Sun?

The closest star that is not our Sun is the Proxima Centaury of the Alpha Centaury star system. Alpha Centauri is a double-star (and partly triple-star) system, consisting of the Alpha Centauri A and B stars and the Proxima Centauri.

Closest Star to Our Sun - Proxima Century
Image source: https://www.nasa.gov/image-feature/goddard/2016/hubbles-best-image-of-alpha-centauri-a-and-b

The Proxima Centauri is about 4.22 light-years away from earth (268,770 AU). However, the faint red dwarf Proxima Centauri is almost a fifth of a light-year from Alpha Centauri A ad B (this is why there’s the debate whether the Proxima Centauri is actually a part of the star system or not).

Proxima Centauri is also a flare star. Meaning, it’s subject to sudden changes in brightness. However, since it’s a fairly faint start, the flare is not very noticeable.

Nevertheless, the Proxima Centauri is the closest star to our star system and is about 620 billion miles (a trillion km) closer than the Alpha Centauri A and B.

How Old Is The Sun?

There are several methods we can use to estimate the age of the Sun, and so far, they all estimate that the Sun is about 4.5 to 5 billion years.

The age of the Sun can be estimated by performing radioactive dating of the oldest meteorites. This is due to the theory that the whole solar system (the Sun, planets including our Earth, and asteroids, etc.) is formed together at the same time.

So, according to this theory, the age of the sun should be close to the age of these oldest meteorites. With this method, G.J. Wasserburg obtained a radioactive dating of (4.57 +/- 0.01) x 10^9 years (4.57 billion years).

Another method is by dating the oldest Earth rocks, which are also about 4.6 billion years. The oldest fossils on earth are estimated to be about 3.5 billion years old, which implies that the Sun has been there at that time, making the Earth a suitable place for life.

So, 3.5 billion years is considered the ‘lower bound’ of the Sun’s age.

Another method of estimating the Sun’s age is to observe the Standard Solar Model, a mathematical model that observes the Sun at various stages in its life while it is burning hydrogen and fusing helium.

With this model, we can check the observable quantities in the model like luminosity, radius, composition, frequencies, and so on to estimate the Sun’s age.

How Long Will Our Sun Live?

The Sun is our solar system’s—and therefore, our Earth’s— source of energy, and without the Sun, we simply won’t live.

However, like anything else, the Sun isn’t designed to have an unlimited lifetime. The Sun is technically a star, and we have observed other stars with limited lifetimes. So, one day, our Sun will die.

The sun is ‘powered’ with a nuclear fusion engine at its core which fuses hydrogen into helium, and it will die when it runs out of fuel.

The Sun, like other stars, was formed when a huge cloud of hydrogen, helium, and other gases grows so large and so it collapses under its own weight. This will create immense pressure at the center of this collapsing mass of gas, creating a massive amount of heat.

With this very high temperature, hydrogen atoms lose their electrons, and naked hydrogen atoms will then fuse together to form helium atoms.

This reaction releases huge energy, big enough to counter the gravity pressure that collapses the cloud of gas in the first place. This intense ‘battle’ between the gravity pressure and the energy created by the fusion reactions is the fuel of our sun (and other stars).

Fortunately, it still has a lot of fuel left, and most experts estimate that our Sun still has around 5 billion years’ worth of fuel. So we shouldn’t need to worry about the Sun’s death anytime soon.

What Will Happen When Our Sun Dies?

As we’ve discussed, the sun will run out of hydrogen, its fuel in around 5 billion years. It’s still a very long time, but it will come nonetheless. The Sun (or solar system’s star) is currently in the most stable phase of its life cycle since the birth of our solar system around 4.5 billion years ago (as discussed above).

When the hydrogen is used up, the sun will grow unstable, and when all the hydrogen atoms have been used up with no hydrogen left to fuse in the core, a shell of fusion hydrogen will form around the Sun’s core (now filled with helium).

This will create a massive gravitational force, which will compress the core. In turn, this will expand the rest of the Sun, and the Sun will grow very large–so large that it will burn the inner planets, including the Earth, and the Sun will transform into a red giant.

After this, for about a billion years, the sun will burn as this red giant. Eventually, the hydrogen in the outer core will also deplete, leaving the helium atoms. The helium atoms will then fuse into heavier elements (carbon, oxygen, etc.) without releasing as much energy.

Once all of these helium atoms are fused, the gravity pressure will be much heavier and the sun will shrink into a white dwarf, leaving behind a planetary nebula (which includes the remnants of our Earth).

When the Sun finally dies, it will eject a mass of dust and gas into space (the envelope) which can be as much as 50% the Sun’s mass. This process will reveal the Sun’s core, which will eventually turn off and die completely.

The YouTube video below does a good job of explaining what will happen when our sun begins to die.

Although there are still ongoing debates around this subject (when the sun will die, what will happen, etc), the fact remains that we still have billions of years before our sun will die, and we shouldn’t need to worry.

End Words

Above, we have discussed some interesting facts surrounding the Sun, the star of our Solar System. The Sun is our solar system’s source of energy, heat, and light, but at the same time is just one among millions if not billions of stars in the vast universe.

While there are many things we have learned about the Sun and the stars, there are also many mysteries we haven’t really understood at all.

There are obviously more facts about the Sun we haven’t included in this article, and many more we didn’t know at all. However, these facts above can be a solid foundation if you want to learn further about our Sun, our solar system, and astronomy in general.