Categories: Guide to Space

How Much Does the Earth Weigh?

Earth is, by any reckoning, a pretty big place. Ever since humanity first began the process of exploring, philosophers and scholars have sought to understand its exact dimensions. In addition to wanting to quantify its diameter, circumference, and surface area, they have also sought to understand just how much weight it packs on.

In terms of mass, Earth is also a pretty big customer. Compared to the other bodies of the Solar System, it is the largest and densest of the rocky planets. And over the course of the past few centuries, our methods for determining its mass have improved – leading to the current estimate of 5.9736×1024kg (1.31668×1025 lbs).

Size and Composition:

With a mean radius of 6,371.0 km (3,958.8 mi), Earth is the largest terrestrial planet in our Solar System. This means that it is composed primarily of silicate rock and metals, which are differentiated between a solid inner core, an outer core of molten metal, and a silicate mantle and crust made of silicate material.

This cutaway of planet Earth shows the familiar exterior of air, water and land as well as the interior: from the mantle down to the outer and inner cores. Credit: Kelvinsong / Wikipedia

Earth is composed approximately of 32% iron, 30% oxygen, 15% silicon, 14% magnesium, 3% sulfur, 2% nickel, 1.5% calcium, and 1.4% aluminum, with the remaining made up of trace elements. Meanwhile, the core region is primarily composed of iron (88.8%), with smaller amounts of nickel (5.8%), sulfur (4.5%), and less than 1% trace elements.

Mass and Density:

Earth is also the densest planet in the Solar System, with a mean density of 5.514 g/cm3 (0.1992 lbs/cu in). Between its size, composition, and the distribution of its matter, the Earth has a mass of 5.9736×1024 kg (~5.97 billion trillion metric tons) or 1.31668×1025 lbs (6.585 billion trillion tons).

But since the Earth’s density is not even throughout – i.e. it is denser towards the core than it is at its outer layers – its mass is also not evenly distributed. In fact, the density of the inner core (at 12.8 to 13.1 g/cm³; 0.4624293 lbs/cu in), while the density of the crust is just 2.2–2.9 g/cm³ (0.079 – 0.1 lbs/cu in).

The layers of the Earth, a differentiated planetary body. Credit: Wikipedia Commons/Surachit

This overall mass and density are also what causes Earth to have a gravitational pull equivalent to 9.8 m/s² (32.18 ft/s2), which is defined as 1 g.

History of Study:

Modern scientists discerned what the mass of the Earth was by studying how things fall towards it. Gravity is created by mass, so the more mass an object has, the more gravity it will pull with. If you can calculate how an object is being accelerated by the gravity of an object, like Earth, you can determine its mass.

In fact, astronomers didn’t accurately know the mass of Mercury or Venus until they finally put spacecraft into orbit around them. They had rough estimates, but once there were orbiting spacecraft, they could make the final mass calculations. We know the mass of Pluto because we can calculate the orbit of its moon Charon.

The Geoid 2005 model, which was based on data of two satellites (CHAMP and GRACE) plus surface data. Credit: GFZ

And by studying other planets in our Solar System, scientists have had a chance to improve the methods and instruments used to study Earth. From all of this comparative analysis, we have learned that Earth outstrips Mars, Venus, and Mercury in terms of size, and all other planets in the Solar System in terms of density.

In short, the saying “it’s a small world” is complete rubbish!

We have written many articles about Earth for Universe Today. Here’s Ten Interesting Facts About Earth, What is the Diameter of the Earth?, How Strong is the Force of Gravity on Earth?, What is the Rotation of the Earth?

If you’d like more info on Earth, check out NASA’s Solar System Exploration Guide on Earth. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.


Matt Williams

Matt Williams is the Curator of Universe Today's Guide to Space. He is also a freelance writer, a science fiction author and a Taekwon-Do instructor. He lives with his family on Vancouver Island in beautiful British Columbia.

Recent Posts

Dust Devils and Strong Winds Produce the Constant Haze on Mars

Dust is an everyday feature on Mars and wreaks havoc on various pieces of equipment…

17 hours ago

Giant Sunspot AR3038 has Doubled in Size and is Pointed Right at Earth. Could be Auroras Coming

Sunspots are typically no real reason to worry, even if they double in size overnight…

20 hours ago

Remember That Rocket That was Going to Crash Into the Moon? Scientists Think They've Found the Crater

The Lunar Reconnaissance Orbiter (LRO) – NASA’s eye-in-the-sky in orbit around the Moon – has…

20 hours ago

Supernovae Were Discovered in all These Galaxies

The Hubble space telescope has provided some of the most spectacular astronomical pictures ever taken.…

22 hours ago

VY Canis Majoris is Dying, and Astronomers are Watching

Three-dimensional models of astronomical objects can be ridiculously complex. They can range from black holes…

23 hours ago

NASA Funds the Development of a Nuclear Reactor on the Moon That Would Last for 10 Years

If NASA's Artemis project to return to the Moon permanently is going to succeed, it…

1 day ago