How Hot Is the Earth’s Core and Does the Temperature Change? 

Weather and climate across our beautiful planet are more important than ever. However, sometimes an unseen part of the equation lies right under our noses – more specifically, under our feet. Hundreds of miles beneath us, and under several layers of different materials, lies the center of Earth. This unimaginable object is not only massive and superheated, it’s also terribly difficult to study. Despite this, it remains a critical piece of the puzzle in making our planet the way it is. Let’s unravel the mysteries surrounding the Earth’s enigmatic core and discover some potentially shocking truths about it!

What Are the Layers of Earth?

As a refresher on the differing segments that make up Earth, let’s first start with the crust. This is the topmost layer and is the only visible one to its inhabitants. Everything from the tallest mountains to the beds of the ocean has the crust as its foundation. Beneath that sits the upper mantle, a mostly solid layer of rock that runs nearly 255 miles deep. Together, the crust and upper mantle are known as the lithosphere. This combined region is where the tectonic plates exist, and they are vital for regulating planetary temperatures.

Beneath the lithosphere lies the asthenosphere, an extremely pliable area of the Earth’s interior. Although current research isn’t sure why this zone is so flexible, melting rocks are thought to be a large contributor. What job does this oddly named layer perform? In general, it is the primary source of magma that we see here on the surface.

Further in, the outer core looms at depths between 1,795 and 3,200 miles underground. Thanks to relatively lower amounts of surrounding pressure, the outer core’s materials exist in a liquid form. This chiefly iron-based region is what primarily generates the planet’s magnetic field. In case you didn’t know, studies indicate that such a field is required for a planet to sustain life!

Finally, sitting at the very center of Earth is the inner core. Unlike its neighboring layer, the inner core is made of solid elements. Oddly enough, research has proven that the inner core spins on its own, even faster than the Earth itself. Every 400 years, it completes an entire revolution where it lies. The speed at which it turns is, geologically speaking, dizzyingly quick.

Does Earth’s Core Temperature Affect Its Surface?

While it’s the result of many complicated, connected systems, yes! All of the ebbs and flows that occur within Earth’s interior eventually affect everything that exists on the surface. For example, all of the superheated events underground, which are the results of reactions within the core, have visible consequences.

One of the most obvious outcomes is volcanoes, whether they’re hulking monoliths found on land or sneaky vents seen along the ocean’s floor. You see, higher core temperatures within our planet provoke shifts beneath us, moving the mighty tectonic plates. As a result, the landmass is moved, a change that inevitably causes magma to flow upwards. Once the pressure builds to a certain level, volcanoes are born as Earth vents the related energy. As you might assume, earthquakes are another obvious symptom during the transition of great volumes of mass and force.

Another product of high inner temperatures is far more subtle. What might be gigantic changes inside the Earth ripple off and cause almost invisible changes topside. Basically, the surface temperature varies by fractions of a degree as cycles chug along in the interior. Other slight transitions occur as well, such as several milliseconds of time appearing or disappearing from a day’s total length. Researchers need to use rather delicate instrumentation to pick up these changes, which appear to take place over decades or longer.

While even trickier to detect and observe, even small shifts within the planetary core may also influence Earth’s magnetic field. While scientists are still trying to figure out all of the side effects this brings, one possibility is that cloud formation is likely altered. In exchange, the natural protection that clouds provide against solar radiation is impacted.

How Is the Inside of Earth Studied?

No attempts to delve deep into the surface of Earth have ever gotten very far. The deepest cave, Veryovkina Cave, only goes 7,257 feet below the ground. The deepest point in the ocean, found within the Mariana Trench, was measured at approximately 36,037 feet. In contrast, the deepest artificial hole ever created, the Kola Superdeep Borehole, reached a staggering 40,229 feet deep. While even that sounds impressive, even that is several miles short of poking through the crust, the uppermost layer!

With no way to crawl, swim, or dig deep enough to study things up close, how do scientists get a better picture of each layer of Earth? Surprisingly enough, the answer lies within earthquakes. These naturally occurring tremblings are caused by energy escaping from the lithosphere. With a multitude occurring every year, researchers have plenty of opportunities to examine a vast array of information. The readings they gather from seismic events are analyzed and interpreted. In turn, light is shed on the inner workings of the planet.

The concept of two cores within Earth would not have been discovered as we know it if not for Inge Lehmann, a Danish seismologist. After observing a quake near New Zealand, she hypothesized that the planet contained both a solid and liquid core, unlike prior theories. Her studies spanned over seven years, which upon completion she published. Although it took another 34 years for these findings to be confirmed, it was critical pioneering that paved the way to contemporary planetology.

Lastly, scientists are also able to create scaled simulations to visualize and study core mechanics. Using satellites to observe Earth’s magnetic patterns can also be used to measure the effects of Earth’s core.

What is Earth’s Core Temperature?

At this point, we can truly see the complex nature of the Earth’s interior along with the innumerable secrets it still holds. Originally, the temperature at the deepest places within the planet was thought to be slightly cooler, with a window of 9,300°F to 9,800°F. However, research has recently progressed to allow for more precise estimations of what its internal temperatures may be.

Earth’s core is a scorching 10,754°F on average, although this can fluctuate between 9,854°F to 11,654°F depending on varying environmental factors. The Earth’s current rotation, differing amounts of elements within the core, and differing pressure levels all influence the possible range of temperatures.

For comparison, the surface of the sun is normally around 10,340°F, with slight variations of its own!

Does Earth’s Inner Temperature Change Over Time?

Contemporary reasoning states that the original formation of Earth trapped a great deal of energy and therefore heat. While it’s only possible to surmise, the extreme temperatures present during the accretion of Earth may have been as high as 17,540°F, if not more. This residual heat still radiates to this day, contributing to a large source of the high temperatures found within the planet. Another supplier of internal heat is radioactive decay, although most of this takes place within the mantle and not the core sections themselves.

It’s important to note the thermodynamic nature of the energy that was stored billions of years ago, as it will slowly burn away over time without replenishing. Also, in regard to the decaying radioactive elements, these eventually disintegrate as well once their atomic lifetime is up. That said, these limited resources and the fact that the prior searing temperatures are no longer present must be taken into account when considering Earth’s internal cooling.

From there, it’s obvious to see that the internal temperature of Earth is dropping, albeit at an exceedingly slow rate. Not to worry though, as it will likely take billions more years for the planet to lose a significant amount of heat, and billions extra to go completely cold. Besides, there would be other bizarre concerns that far into the future, including the inner core expanding too far or the sun going out – things too surreal to fathom seeing during our lifetimes!

Earth’s Core Temperatures in Summary

Science and technology are always changing and so does the way that researchers obtain and interpret data. That said, what we currently know about the composition of Earth’s interior and how it behaves could change upon a single discovery. Models and formulas may become more accurate or replaced entirely, depending on what breakthroughs are made. Recall that not too long ago, scientists proposed theories that Earth was hollow inside until experimentation came along and dispelled them! In all seriousness, what we currently know is likely the closest we’ve ever been to understanding, but there is so much more to be learned.

The photo featured at the top of this post is © iStock.com/Rost-9D