You probably know about the mnemonic “My Very Educated Mother Just Served Us Noodles.”

Indeed, it’s what most students learn about when studying the distance of the planets from the Sun i.e. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

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While this is probably public knowledge, very few people are actually aware of the size of the planets in order. Sure, you may have heard a thing or two about the second smallest planet in our solar system –Mars- from a couple of sci-fi movies. But, do you really know how it compares to the rest of the other planets out there?

Well, our guess is you probably don’t. If you’ve ever wondered about the actual size of the planets in order, then, it’s your lucky day. Here’s how they rank according to size.

A Mnemonic for the Size of the Planets in Order

Before we get started with the countdown, it’s only honorable that we share a mnemonic for the size of the planets in order having already done the same for the distance of the planets from the Sun.

It’s a real easy one too. To ensure that the list stays stuck, just think of something along the lines of “Mercury Met Venus Every Night Until Saturn Jumped.” Essentially, this indicates that the size of the planets in order from smallest to largest is Mercury, Mars, Venus, Earth, Neptune, Uranus, Saturn, and Jupiter.

Pretty cool right?

A Comprehensive Review of the Size of the Planets in Order

1. Mercury

Other than being the smallest planet in the solar system, Mercury is interestingly smaller than Earth’s Moon and extremely hot with temperatures registered going as high as 850 Fahrenheit (454.444 Celsius).

In a bid to learn more about the planet, NASA deployed the MESSENGER probe way back in 2004. Today, we’ve ascertained that its orbit time is equivalent to 88 Earth days and that a single day on the planet lasts about 59 Earth days.

To really get a gist of its diminutive size, the diameter is a little bit over 3,000 miles (4828.032 kilometers).

2. Mars

The red-planet is the second smallest planet in the solar system. It’s also regarded as the last terrestrial planet and potentially has the capability to support human life once the right technology is in place. Given this background, it’s understandable why SpaceX and NASA have accorded the planet so much attention in recent years.

While this is still a far-off dream, the planet is currently inhabited by robots who are continually digging up more intel on Mars. At present, we know that the gravity on Mars is a third of what’s found on Earth and that a single Martian day (called a sol), is actually equivalent to 25 hours.

3. Venus


Named after the Roman goddess of love, Venus is remarkably much hotter than Mercury and filled to the brim with greenhouse gases

The planet has an average diameter of 7,500 miles (12,070.08 kilometers) and its orbit takes about 225 Earth days to complete. With regards to the length of the day, let’s just say that you shouldn’t hold your breath for the day to end since the planet has a day span equivalent to 241 Earth days.

4. Earth

It’s our home planet and the only one known to maintain and support life. Having been formed some 4 billion years ago, the Earth has radically transformed with the passing of time. Thanks to the tilting nature of its axis, Earth experiences 4 seasons and the only natural satellite, the Moon is responsible for the ocean tides.

With an almost 8,000 mile (12874.75 kilometers) diameter, the Earth takes 365 days to orbit the Sun, and an Earth day lasts 24 hours.

5. Neptune

As the 8th planet from the Sun, Neptune is the very last of the gas giants. Constitutionally wise, it’s primarily made up of helium and hydrogen.


While it’s a known fact that the blue coloring emanates from an abundance of methane, it remains unclear whether Neptune’s core is solid

With a diameter of 30,755 miles (49,495.375 kilometers), for Neptune to orbit the Sun, it takes about 165 Earth years and a single day on the planet is equivalent to 19 hours on Earth.

6. Uranus

It’s the third of the gas giants and despite having been discovered in the 1780s, we only managed to catch the very first glimpse of the planet in 1986 as the Voyager probe was making its rounds.

Scientists believe that the core of Uranus is actually extremely icy which makes it unique because most other planets are presumed to be molten.

With a diameter of 31,760 miles, Uranus takes an equivalent of 84 Earth years to orbit the Sun and a single day on the planet translates to 18 Earth years.

7. Saturn

This planet doubles up as the second largest planet and is also the second gas giant. Most recognizable by its one-of-a-kind rings which arose thanks to the action of ice and space debris.

While the planet is largely made up of helium and hydrogen, it remains to be discovered whether Saturn has a solid core or not.

The planet has a large diameter spanning 75,000 miles (120,700.8 kilometers) and takes about 30 Earth years to orbit the Sun. If you’re looking to spend a day on Saturn, then, you’d have to wait an equivalent of 11 Earth hours for a day to pass.

8. Jupiter


As the very first of the gas giants, Jupiter is the largest planet in our solar system

Constitutionally speaking Jupiter consists of helium and hydrogen and just like Saturn, it remains to be seen whether the core is made up of solid matter or not.

With a diameter of 86,881 miles (139,821.42 kilometers), the planet is so massive that if it were 80 times larger, it would qualify to be a star. To orbit the sun, Jupiter takes about 12 Earth years and a single day on the planet is equivalent to 9 Earth hours.

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There you have it, a comprehensive review of the size of the planets in order. Having highlighted the various attributes of the planets, we’re confident you’re loaded with sufficient knowledge to teach an elementary class a thing or two about the heavens.

If you’re not that confident, you can stock up on your knowledge of the cosmos by having a look at our fantastically crafted augmented reality 3D model of the Solar System in all its glory. We promise two things from the experience, an immersive learning experience and loads of fun to be had!