Why Is Venus Called Earth’s Sister?

In this article, we’re going to discuss why Venus is called earth’s sister. We’re going to give an overview of the similarities that exist between Earth and Venus, and the reason they are titled, siblings. Of course, we will also discuss the differences between these two planets, and explain why Venus is inhospitable to human life. 

Why Are Venus And Earth Siblings?

Mass, Size, And Density

One of the most notable similarities between Venus and Earth is that they have a similar size mass. The earth’s mass amounts to 5.97 × 10²⁴ kilograms. Comparatively, Venus has a mass of 4.86 × 10²⁴.

If you were to work out the percentage, Venus has 81.5% of Earth’s mass. Moreover, the difference in radius between Venus and Earth is only 5% -- Earth has a radius of 6070 km, while Venus has a radius of 6050 km. 

As you can see, when one looks at the size and mass of these two planets, they are vastly similar. What is more, both of these planets are rocky, which gives them a very similar density.

If you were to look at these two planets next to each other, the outward similarities are astronomical. While they do not by any means look identical, they look vastly similar, especially if you compare Earth to other planets e.g., Saturn.


Another similarity between Venus and Earth is that the Venusian surface contains thousands of volcanoes. In fact, two-thirds of Venus’s surface is covered by volcanoes. While this rocky planet is a volcanic wonderland, the structure of the volcanoes is vastly different from Earth’s.

When we think of volcanoes, we generally think of huge, mountainous peaks that spit lava. While Venus has raging volcanoes, they are actually flat. One of Venus’s volcanoes, Saps Mons, covers 250 miles (402.34 kilometers) of surface area, and yet only rises to 475² feet.

One reason why volcanoes in Venus have a vastly different structure to Earth’s volcanoes is that the temperature of Venus and thus the pressure is so great. As a result, the volcanoes do not vertically impose to the extent of Earth’s volcanoes.


Venus, much like Earth, is home to mountains regions. In fact, Venus has six mountain regions, that makeup ⅓ of the surface. If you’re really into Venus, then you’ve probably heard of its tallest mountain range, Maxwell Montes.

The mountain here rises up to 7 miles (11.27 kilometers), its surface length amounts to a stunning 540 miles (869.05 kilometers). While Venus does not have mountains similar to Earth, due to its mountainous landscape, it contributes to the view that Venus is a sister planet of Earth.

Key Differences Between Venus And Earth

While Venus and Earth are called sister planets, and they do share their similarities, they certainly are not twins. There are major differences between these two planets, and in several ways, they could not be more different.

Temperature And Atmosphere

Venus is known for its hellish atmosphere. It has a heavier atmosphere than any other discovered planet. This is because the atmosphere mainly contains carbon dioxide and clouds full of sulfuric acid. The surface pressure is a massive 90 times that of Earth’s.

To highlight the sheer extent of this, consider the pressure of the ocean. Venus’s surface pressure is comparable to the pressure that exists 3,300 feet deep in Earth’s ocean. When it comes to heat, it also ranks number one in the solar system. The temperatures of Venus can reach up to an astounding 880 degrees Fahrenheit.

To highlight the sheer temperature of this planet, if we were to place lead on this planet, it will completely melt. Any spacecraft that has landed on this fiery planet reaches a scorching end, only surviving up to a few hours after landing.

Water covers roughly 71.1% of Earth’s surface, and the ocean contains around 96% of our total water. Venus, on the other hand, is incredibly dry. While you might find tiny traces of water in their clouds, you will not find any liquid on this planet.

During Venus’s evolution, ultraviolet rays stemming from the sun evaporated water at such a rate, it caused a prolonged molten state.

Ironically, it has been argued that Venus may have, at one point, been able to sustain life. Whether this is true, or false, it remains that Venus in the present day is one of the fieriest planets in our solar system, and cannot sustain life.


Interestingly, Venus has an orbit vastly different from Earth. It takes Venus 243 Earth days to rotate on its axis, This is the slowest amount of time it takes any major planet.

What’s more, Venus rotates clockwise on its axis, while all other planets rotate anti-clockwise. While Venus rotates clockwise on its axis, it is similar to all other planets, in that it orbits the Sun in an anti-clockwise direction.

Why, and how? It is said that Venus was knocked off its original upright position, this caused such a tilt, that now the planet is upside down.

Moving on, it takes Venus 225 Earth days to orbit the sun. That one year on Venus is equivalent to 225 Earth days. It’s certainly a planet with its unique qualities.


To conclude, Venus is called Earth’s sister planet because, in the grand scheme of things, they share some crucial similarities. These similarities are parted by the vast differences between the planets.

Let us state that Venus has a size, dentistry, and mass. When one compares them, they look vaguely similar, due to these outward physical attributes.

When it comes to the atmosphere, temperature, and orbit of Venus, it could not be further away from Earth. You might hear Venus being called the ‘evil’ sister, due to its fiery nature.

While at some point in time, Venus may have been able to sustain life, it is certainly not a planet that we could call home. With spacecraft boiling and being scorched within hours of arrival, and clouds full of sulfuric acid, it’s a sister you’re not going to want to visit. 

Gordon Watts