Current Event: Hot Water in Icy Space

Enceladus, an icy moon orbiting Saturn, is quickly becoming one of the hottest spots in the search for life beyond Earth. A group of scientists recently determined that hydrothermal vents (flows of heated water) likely exist in a global ocean beneath Enceladus’s icy crust. These vents could possibly be home to life forms. Like only a few known satellites, Enceladus shows signs of ongoing geological activity. Scientists have observed a plume of particles erupting from Enceladus’s south polar region. The plume is fed by several individual jets on the surface of the moon that release mostly water vapor and grains of water ice. The scientists found molecular hydrogen (H₂) in Enceladus’s plumes. Such hydrogen is thought to be rare in planetary bodies as small as Enceladus. The scientists determined that the hydrogen most likely came from hydrothermal vents on a sea floor within Enceladus. On Earth, hydrothermal vents are places where heated water flows from the ocean floor. Some deep-sea vents support diverse and exotic communities of marine life. Certain microbes can use the heat of the water to produce energy. These microbes are in turn consumed or harbored by larger organisms. Scientists suspect that life could flourish around such vents on other planets or moons.

Enceladus, a moon of Saturn, contains geysers at its south polar region that spray water vapor and grains of water ice into space. Credit: NASA/JPL/Space Science Institute

Objective:

Saturn is the second-largest planet in the solar system and the sixth from the Sun. Saturn can be seen from Earth with the unaided eye and was the farthest planet from Earth known to ancient observers. Astronomers believe that the planet is a giant ball of hydrogen and helium with no solid surface. Saturn’s most famous feature is its gleaming rings. Saturn’s rings consist of ice particles that travel around the planet. It has seven main rings, which vary greatly in width. Saturn’s rings cannot be seen from Earth with the unaided eye. In addition to the rings, Saturn has several large moons and dozens of smaller satellites. Saturn’s largest moon, Titan, has an atmosphere thicker than that of Earth. Enceladus, another moon, has erupting geysers that spew water ice and organic (carbon-bearing) molecules into space. The Behind the Headlines news story and related World Book articles explore Saturn and other astronomical topics.

Words to know:

• Astronomy
• Cassini
• Enceladus
• Hydrothermal vent
• National Aeronautics and Space Administration (NASA)
• Planet
• Satellite
• Saturn
• Solar system
• Space exploration

Discussion Topics:

1. Ask your students if they can name the eight planets and five dwarf planets that are in the solar system. (The eight planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. The five dwarf planets are Ceres, Eris, Haumea, Makemake, and Pluto.)

2. Ask your students to debate: “Is it worth it for countries to spend a lot of money on space exploration programs? Why or why not?”

3. Private companies have begun launching people into space. Ask your students if they would want to visit another planet or any other celestial body. Assuming they could safely travel anywhere in space, where would they go? Would they go if they knew they could never return to Earth?

4. Ask your students to use World Book’s Timelines feature to view or add to the Advances in Astronomy timeline. (Students may wish to use World Book’s “Astronomy” article for help.)