The polar regions on Mars and Earth are barren, frozen territory, but are polar regions on all planets in the solar system alike? Are Mercury's polar regions boiling oceans because they're so close to the Sun?
We know a lot about the poles on Earth and Mars, but much less is known about the poles on the other seven planets in our Solar System. Thanks to advanced telescopes and data from orbiter missions, scientists are learning some interesting facts about polar regions on other planets.
Despite its close proximity to the sun, nighttime temperatures on Mercury can drop as low as -183° degrees C (-297° degrees F). Because of this, and the fact that it has very little atmosphere to keep it warm, it is possible for ice to exist on Mercury. Radar imaging of Mercury shows that ice is possibly stored in permanently shadowed craters at both poles.
A "polar dipole" has been observed at Venus' north pole. A polar dipole is a vast vortex that rotates around the pole and is bounded by a "polar collar"
(a ring that surrounds the polar regions).
Extreme cold temperatures and heavy glaciation occur at both of Earth's poles. Polar ice caps made of water ice rest on land at the south pole (continent of Antarctica) and on ocean at the north pole (Arctic Circle). Extreme variations in daylight hours occur, with 24 hours of daylight in mid-summer and permanent darkness in mid-winter.
Mars has polar ice caps consisting of both water ice and carbon dioxide ice. Both caps contain a permanent, year-round ice cap made of water ice and a seasonal cap of carbon dioxide ice that forms in winter and disappears in summer. In the northern polar region, the permanent cap is made of water ice, while the southern permanent cap is mostly carbon dioxide ice mixed with some water ice.
Jupiter's polar regions have auroras, similar to the Northern Lights on Earth. In addition, a "Great Dark Spot" swirls near Jupiter's north pole, which scientists believe is a curious side effect of Jupiter's powerful auroras.
Saturn is a large, gas planet that spins very fast on its axis. Because of the centrifugal force associated with the rapid spinning, Saturn's equator bulges and its poles are "flattened."
Uranus is so tilted on its axis that it rotates on its side. Because of this, its poles are sometimes pointed directly at the Sun. For part if its orbit, one pole faces the sun continuously, while the other pole faces away. Scientists are uncertain which of Uranus' poles is south and which is north.
Because Neptune's axis is tilted 30 degrees, its poles remain in constant sunlight for 41 years during the summer season. Bright regions have been observed at the poles, which are thought to be produced by a haze of ice crystals.
Pluto's polar regions are made of frozen methane and nitrogen. During orbit phases when Pluto is closer to the Sun, the methane and nitrogen thaw, rise, and form a temporary atmosphere.