Mars/mɑːrz/ Definition 1 of 3Pro Tip 1/3Astronomical Term The name 'Mars' is always capitalized when referring to the planet to differentiate it from the verb. Astronomers study Mars' atmosphere. Pro Tip 2/3Not Just Red While Mars is known for being red, its landscape varies with ice caps and dark soil. Pictures show that Mars has polar ice caps. Pro Tip 3/3Space Missions Often mentioned in the context of space exploration and future human colonization. NASA plans to send astronauts to Mars.