Visit Your Local PBS Station PBS Home PBS Home Programs A-Z TV Schedules Watch Video Donate Shop PBS Search PBS
Life Beyond Earth Banner Are We Alone? Is Anybody Listening? Resources
Highway Through Time | The Habitable Zone | Terraforming Mars | Venus | Europa | Titan
Titan title
Titan Blanketed by an impenetrably thick, clouded atmosphere, the surface of Titan, Saturn's largest satellite, remains shrouded in mystery. Yet the same atmosphere that keeps us from seeing the planet's true face might be the key to understanding how life gets started.

Titan is the only moon in the solar system with a significantly dense atmosphere. Composed primarily of nitrogen, with low percentages of argon and methane, its atmosphere also contains trace amounts of organic compounds known as liquid hydrocarbons. These hydrocarbons form as methane, dominating Titan's upper atmosphere. The liquid hydrocarbons are thought to rain down on Titan's surface, potentially forming large lakes and creating conditions similar to those of the primordial Earth when terrestrial life originated.

Recent infrared photographs taken by the Hubble Space Telescope show large bright and dark regions on Titan's surface that may indicate the presence of continental landmasses. Answers should come when the Cassini Saturn Orbiter and Huygens Titan Probe reach Titan in the summer of 2004. The goal of the Huygens probe — named after Titan's discoverer, the Dutch astronomer Christiaan Huygens — is to learn more about Titan's atmosphere and surface.
Titan Facts
Discovery:
Saturn's moon Titan was discovered by the Dutch astronomer Christiaan Huygens in 1655. Huygens, who was also the first to correctly interpret Saturn's ring structure, was able to make these observations using his improved telescopic lens.

Exploration:
In 1979, the Pioneer 11 spacecraft reached Saturn and calculated the temperature on Titan, concluding at that time that Titan was too cold to support life. The Voyager 1 spacecraft honed in on Titan in its 1980 mission. Due to the thick cloud cover, Voyager could not capture Titan's surface on film, though other data was collected.

The Cassini mission, with its spacecraft now en route, is hoped to yield the first detailed look at Titan's surface. When the Cassini spacecraft arrives in 2004, it will drop the European Space Agency's Huygens Probe into Titan's atmosphere. The probe will collect atmospheric data as it descends to the ground. Once the probe lands, it will then measure wind, weather, energy flux and surface features — relaying the information back to the Cassini spacecraft.


Atmosphere:
Titan is the only moon in the solar system with a significantly dense atmosphere, rich in methane and nitrogen. These two components — along with the help of solar ultraviolet light — are the necessary ingredients for organic compound formation.


Size:
Titan is Saturn's largest satellite. At more than 5,150 kilometers in diameter, this moon is about the size of Mars and Mercury combined.

Orbit:
Titan has an orbital period around Saturn of approximately 16 days. Its distance from Saturn is approximately 1,220,000 kilometers.

Magnetic fields:
Titan has no magnetic field and sometimes orbits outside of the Saturn magnetosphere. Because of this, Titan is exposed to intense solar winds, which may ionize and carry away some of its atmospheric molecules.

Water:
With the prevalence of carbon monoxide and carbon dioxide in Titan's atmosphere, scientists have long thought that liquid water might exist on Titan's surface. In 1998, the European Space Agency's Infrared Space Observatory (ISO) detected water vapor in the atmosphere of Titan. Due to Titan's huge distance from the Sun, the surface temperatures are seemingly too cold to support liquid water. But scientists say it is possible that an impact pool created by a comet or asteroid could maintain liquid water for as long as 1,000 years — perhaps long enough for life's chemical reactions to take place.
end rule