In Hawai'i we're surrounded by ocean. We swim, sail, fish, gaze at and smell it every day, but where does it come from?

How did water get to Earth? Do other planets have oceans? Why does the Earth have dry land? Five scientists will address these questions and more tomorrow in "Origins of Oceans," a panel presentation at the University of Hawai'i-Manoa.

"The story of the oceans starts with the formation of water vapor molecules in the winds from giant stars many billions of years ago," said astronomer Robert Jedicke.

"The water molecules condensed to make tiny ice grains which drifted around the Milky Way Galaxy until they were swept up into the spinning cloud that became the solar system. Much of the solar system ice ended up as comets, and whenever these icy objects hit the Earth, its water would become part of our future biosphere."

Delivery of water to the planet, however, is only part of the story. UH oceanographer Michael Mottl explains there's also geochemical evidence from deep within Earth's mantle.

How these conditions allow liquid water to be present on Earth's surface will be the nub of Mottl's presentation.

"Water is the single key compound to make life," Mottl said.

Jedicke and Mottl will be joined by astrobiologist Karen Meech; Stephen Mojzsis, geologist at the University of Colorado; and Torrence Johnson, planetary scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

Reach Chris Oliver at coliver@honoluluadvertiser.com.