Physical Characteristics
Mars has approximately half the diameter of Earth. It is less dense than Earth, having about 15% of Earth's volume and 11% of the mass. Its surface area is only slightly less than the total area of Earth's dry land. While Mars is larger and more massive than Mercury, Mercury has a higher density. This results in the two planets having a nearly identical gravitational pull at the surface—that of Mars is stronger by less than 1%. The red-orange appearance of the Martian surface is caused by iron(III) oxide, more commonly known as hematite, or rust. It can also look butterscotch, and other common surface colors include golden, brown, tan, and greenish, depending on minerals.
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Famous quotes containing the word physical:
“Whenever reality reinforces a child’s fantasied dangers, the child will have more difficulty in overcoming them...So, while parents may not regard a spanking as a physical attack or an assault on a child’s body, the child may regard it as such, and experience it as a confirmation of his fears that grown-ups under certain circumstances can really hurt you.”
—Selma H. Fraiberg (20th century)