Understanding Singular, Plural, and Possessive Forms: The Case of “Mars”

Grasping the concepts of singular, plural, and possessive forms in English can sometimes be a bit tricky, especially with proper nouns like “Mars.” In this article, we’ll explore how to correctly use “Mars,” “Mars’,” and “Mars’s” in sentences, making it simple to understand through explanations and a handy table.

Singular and Plural Forms

Singular and Plural Forms

Singular Form

“Mars” refers to the fourth planet from the Sun, known for its reddish appearance. In this instance, “Mars” is a singular noun because it denotes one specific celestial body.

Plural Form

The plural form is used when referring to more than one of something. However, in the case of “Mars,” we rarely use a plural form because there is only one Mars in our solar system. This makes the concept of a plural form for “Mars” unnecessary for most practical purposes.

Possessive Forms

The possessive form is where it gets interesting, especially with singular nouns ending in “s.” Let’s break down how to form the possessive with “Mars.”

Mars’s or Mars’?

The possessive form of “Mars” can be written in two ways: “Mars’s” or “Mars’.” Both forms are grammatically correct, and the choice between them often comes down to style guides or personal preference.

  • Mars’s: This form is recommended by style guides that prefer adding ’s to singular nouns ending in “s,” including proper nouns. It indicates that something belongs to Mars.
  • Mars’: Other style guides suggest simply adding an apostrophe after the “s” for nouns ending in “s,” especially for proper nouns. This form is also correct and widely accepted.

When to Use Each Form

  • Use Mars’s when you want to follow the style that adds ’s to all singular possessive forms, even when the noun ends in “s.”
  • Use Mars’ if you prefer the style that applies only an apostrophe to singular nouns ending in “s.”

Read More: Understanding “Sundays or Sunday’s?”: A Guide to Singular, Plural, and Possessive Forms

Table for Better Understanding

Table for Better Understanding

To clarify, let’s look at a table summarizing the usage:

FormWhen to UseExample Sentence
MarsReferring to the planet itself.“Mars is known as the Red Planet.”
Mars’sPossessive form (style 1).“Mars’s atmosphere is thin and cold.”
Mars’Possessive form (style 2).“Mars’ atmosphere is mostly carbon dioxide.”

Examples in Sentences

  • Mars: “NASA’s rover sent back stunning images of Mars.”
  • Mars’s: “Mars’s largest moon, Phobos, is slowly spiraling inward toward the planet.”
  • Mars’: “The exploration of Mars’ surface has provided valuable insights into its geological history.”


Understanding when and how to use “Mars,” “Mars’s,” and “Mars'” correctly is essential for clear and accurate communication, especially when writing about this fascinating planet. Remember, the choice between “Mars’s” and “Mars'” comes down to style preference, but both are correct. By keeping these guidelines in mind, you can confidently write about Mars, its characteristics, and its features without hesitation.

Whether you’re writing an academic paper, a blog post, or just curious about proper grammar usage, the key is consistency. Choose the style that best fits your needs and stick with it throughout your writing. This way, your readers will not only appreciate your content but also the clarity and consistency of your writing style.

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