Top 10 Extreme Planet Facts

Strange, But True - Our Solar System

Credit: IAU/Martin KornmesserThe worlds around our sun run the gamut from small and lifeless chunks of rock to gargantuan globes of gas. Our planet's siblings each have its own extreme features and crazy phenomena. -- Charles Q. Choi

Top 10 Extreme Planet Facts

1. The air of Earth

Credit: NASAIt might seem a bit like navel-gazing to point out how special Earth is — after all, we live here. Although Earth is covered in oceans of water, Mars could have once hosted seas as well. But nowhere else in the solar system can one find atmospheres loaded with free oxygen, which ultimately proved vital to one of the other unique features of Earth — us.



2. The Great Red Spot of Jupiter

Credit: NASA/ESA/A. Simon-Miller (NASA Goddard Space Flight Center)The most extraordinary feature on Jupiter's surface is undoubtedly the Great Red Spot, a giant storm seen for more than 300 years. At its widest diameter, the Great Red Spot is roughly three times as wide as Earth. Every now and again, the spot fades entirely.


3. The hexagon of Saturn

Credit: NASA/JPL/Space Science InstituteSaturn may be most famous for its spectacular rings, but Jupiter, Uranus and Neptune have rings too. However, nothing like the giant hexagon circling Saturn's north pole has ever been seen on any other planet, with each of its sides nearly 7,500 miles (12,500 kilometers) across — big enough to fit nearly four Earths inside. Thermal images show it reaches some 60 miles (100 kilometers) down into the planet's atmosphere. Scientists have bandied about several other ideas concerning the hexagon's origin. One such idea is that the hexagon arises from a complex interaction between waves undulating through the atmosphere and gas churning up.


4. The storms of Mars

Credit: NASA/JPL-Caltech/Malin Space Science SystemsThe dust storms of Mars are the largest in the solar system, capable of blanketing the entire red planet and lasting for months. One theory as to why dust storms can grow so big on Mars starts with airborne dust particles absorbing sunlight, warming the Martian atmosphere in their vicinity. Warm pockets of air flow toward colder regions, generating winds. Strong winds lift more dust off the ground, which in turn heats the atmosphere, raising more wind and kicking up more dust.

5. The rings of Saturn

Credit: NASA/JPLSaturn is most famous for its spectacular rings. One ring, too faint to be seen from Earth and discovered just in 2009, measures at least 200 times the diameter of the planet — a billion Earths could fit inside the ring.


6. The winds of Neptune

Credit: NASA/JPLOn Neptune, one can find jet stream winds traveling at more than 1,500 mph. It remains a mystery as to how it gets the energy to drive the fastest planetary winds seen in the solar system, despite it being so far from the sun — at times farther from the sun than Pluto — and having relatively weak internal heat.


7. The weird tilt of Uranus

Credit: NASA and Erich Karkoschka, U. of ArizonaUnlike other worlds, Uranus is tilted so far that it essentially orbits the sun on its side, with the axis of its spin nearly pointing at the star. Many astronomers believe this unusual orientation might be due to a collision with an Earth-sized planet soon after it was formed.

8. The highs and lows of Mars

Credit: NASA/JPLThe red planet is home to both the highest mountain and the deepest, longest valley in the solar system. Olympus Mons is roughly 17 miles (27 kilometers) high, about three times as tall as Mount Everest, while the Valles Marineris can go as deep as 5 to 6 miles (8 to 10 kilometers) in some places and runs for roughly 2,500 miles (4,000 kilometers), which is close to the width of Australia or the distance from Philadelphia to San Diego.


9. The wild temperature swings of Mercury

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of WashingtonAs the planet nearest the sun, the surface of Mercury can reach a scorching 840 degrees F (450 degrees C). However, since this world doesn't have enough atmosphere to entrap any hName: Nine Planets Becomeat,Name: Nine Planets Becom at ight temperatures can plummet to -275 degrees F (-170 degrees C), a more than 1,100 degrees F temperature swing that is the greatest in the solar system.


10. The blistering surface of Venus

Credit: NASAAlthough Venus is only the planet second nearest the sun, its dense, toxic atmosphere traps heat in a runaway version of the greenhouse effect that warms up the Earth. As a result, temperatures on Venus reach 870 degrees F (465 degrees C), more than hot enough to melt lead.

NASA Telescope Confirms Alien Planet in Habitable Zone

This story was updated at 12:15 p.m. ET.


MOUNTAIN VIEW, Calif. — NASA's planet-hunting Kepler spacecraft has confirmed the discovery of its first alien world in its host star's habitable zone — that just-right range of distances that could allow liquid water to exist — and found more than 1,000 new explanet candidates, researchers announced today (Dec. 5).

The new finds bring the Kepler space telescope's total haul to 2,326 potential planets in its first 16 months of operation.These discoveries, if confirmed, would quadruple the current tally of worlds known to exist beyond our solar system, which recently topped 700.

The potentially habitable alien world, a first for Kepler, orbits a star very much like our own sun. The discovery brings scientists one step closer to finding a planet like our own — one which could conceivably harbor life, scientists said.

"We're getting closer and closer to discovering the so-called 'Goldilocks planet,'" Pete Worden, director of NASA's Ames Research Center in Moffett Field, Calif., said during a press conference today. [Gallery: The Strangest Alien Planets]

The newfound planet in the habitable zone is called Kepler-22b. It is located about 600 light-years away, orbiting a sun-like star.

Kepler-22b's radius is 2.4 times that of Earth, and the two planets have roughly similar temperatures. If the greenhouse effect operates there similarly to how it does on Earth, the average surface temperature on Kepler-22b would be 72 degrees Fahrenheit (22 degrees Celsius).

Hunting down alien planets

The $600 million Kepler observatory launched in March 2009 to hunt for Earth-size alien planets in the habitable zone of their parent stars, where liquid water, and perhaps even life, might be able to exist.

Kepler detects alien planets using what's called the "transit method." It searches for tiny, telltale dips in a star's brightness caused when a planet transits — or crosses in front of — the star from Earth's perspective, blocking a fraction of the star's light.

The finds graduate from "candidates" to full-fledged planets after follow-up observations confirm that they're not false alarms. This process, which is usually done with large, ground-based telescopes, can take about a year.

The Kepler team released data from its first 13 months of operation back in February, announcing that the instrument had detected 1,235 planet candidates, including 54 in the habitable zone and 68 that are roughly Earth-size.

Of the total 2,326 candidate planets that Kepler has found to date, 207 are approximately Earth-size. More of them, 680, are a bit larger than our planet, falling into the "super-Earth" category. The total number of candidate planets in the habitable zones of their stars is now 48.

To date, just over two dozen of these potential exoplanets have been confirmed, but Kepler scientists have estimated that at least 80 percent of the instrument's discoveries should end up being the real deal.

More discoveries to come

The newfound 1,094 planet candidates are the fruit of Kepler's labors during its first 16 months of science work, from May 2009 to September 2010. And they won't be the last of the prolific instrument's discoveries.

"This is a major milestone on the road to finding Earth's twin," Douglas Hudgins, Kepler programscientist at NASA headquarters in Washington, D.C., said in a statement.

Mission scientists still need to analyze data from the last two years and on into the future. Kepler will be making observations for a while yet to come; its nominal mission is set to end in November 2012, but the Kepler team is preparing a proposal to extend the instrument's operations for another year or more.

Kepler's finds should only get more exciting as time goes on, researchers say.

"We're pushing down to smaller planets and longer orbital periods," said Natalie Batalha, Kepler deputy science team lead at Ames.

To flag a potential planet, the instrument generally needs to witness three transits. Planets that make three transits in just a few months must be pretty close to their parent stars; as a result, many of the alien worlds Kepler spotted early on have been blisteringly hot places that aren't great candidates for harboring life as we know it.

Given more time, however, a wealth of more distantly orbiting — and perhaps more Earth-like — exoplanets should open up to Kepler. If intelligent aliens were studying our solar system with their own version of Kepler, after all, it would take them three years to detect our home planet.

"We are getting very close," Batalha said. "We are homing in on the truly Earth-size, habitable planets."