Planum Boreum

[1] The main feature of the Planum Boreum is a large fissure or canyon in the polar ice cap called Chasma Boreale.

Planum Boreum interfaces with Vastitas Borealis west of Chasma Boreale at an irregular scarp named Rupes Tenuis.

[5] It has a volume of 1.2 million cubic kilometres and covers an area equivalent to about 1.5 times the size of Texas.

The troughs are roughly perpendicular to the wind direction, which is shifted by the Coriolis effect, leading to the spiral pattern.

[7] Chasma Boreale is a canyon-like feature older than the troughs, and in contrast is aligned parallel to the wind direction.

[9] The Phoenix lander, launched in 2007, arrived at Mars in May 2008 and successfully landed in the Vastitas Borealis region of the planet on May 25, 2008.

[12][13] A large doughnut-shaped cloud appears in North polar region of Mars around the same time every Martian year and of about the same size.

[15] The cloud is thought to be composed of water-ice,[15] so it is white in color, unlike the more common dust storms.

[15] Cyclone-like storms were first detected during the Viking orbital mapping program, but the northern annular cloud is nearly three times larger.

False color HiRISE image of a side of the Chasma Boreale , a canyon in the polar ice cap. Light browns are layers of surface dust greys and blues are layers of water and carbon dioxide ice. Regular geometric cracking is indicative of higher concentrations of water ice.
False color HiRISE view of water ice layers in Olympia Rupes, believed by scientists to be preserving climate conditions of Mars dating back millions of years. Depicted width: 1.3 km ( 3 4 mi)
Hubble view of the colossal polar cloud on Mars