polar cap

noun

1. Geology. the icecap situated at either end of the earth's poles.
2. Astronomy. either of the two bright areas around the poles of the planet Mars, consisting of water ice and frozen carbon dioxide.

polar cap

1. The mass of ice that covers either of the Earth's polar regions year-round.
2. The mass of frozen carbon dioxide and water that covers either of Mars's polar regions.

Word History and Origins

Origin of polar cap¹

First recorded in 1890–95

Example Sentences

These include the bright, white, inner cap and the dark lane in the bottom of the polar cap, toward the lower latitudes.

From Science Daily

Several bright storms can also be seen near and below the southern border of the polar cap.

From Science Daily

The polar cap appears to become more prominent when the planet's pole begins to point toward the Sun, as it approaches solstice and receives more sunlight.

From Science Daily

Webb captured this dynamic world with rings, moons, storms, and other atmospheric features -- including a seasonal polar cap.

From Science Daily

They note that there are several bright storms visible both near and below the southern border of the polar cap.

From Salon