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Biosphere 2 now offers annual memberships so you can go as often as you want.

By Lori Stiles, University Communications
March 20, 2008

It's impossible to dig down farther than about six miles into the Earth.

So how do scientists know for a fact that our planet is solid nickel and iron at its inner core, with a nickel and iron liquid outer core around that, a solid mantle of iron and magnesium silicate around that, topped by the outer layer of crust that we all hang around on?

And then there's the fact that no humans walked the Earth even a few million years ago.

So how do scientists know for certain that the continents once fit together into a supercontinent that later pulled apart like a disassembled jigsaw puzzle? And how do they know that at least half of Earth's species were wiped out in five major mass extinctions that began 250 million years ago?

University of Arizona College of Science Dean and geosciences professor Joaquin Ruiz is a world expert on how isotopes can be used to date all kinds of events in Earth history. He's also a gifted speaker who can tell the story of how Earth evolved from its fiery beginnings into the habitable planet we all depend on.

Ruiz will pack the tale of 4.5 billion years of Earth history into a 45-minute talk called "Earth Evolution: The Formation of Our Planet" at Biosphere 2 on Saturday. His talk, at 1 p.m., is part of the UA Biosphere 2 special spring series called "Science Saturdays."

Ruiz spices his talk with bits of memorable history. For example, those born after the Cold War probably don't know that U.S. naval operations to map the ocean floor in an effort to detect submarines led to the startling discovery that Earth's sea floors are young, far younger than thought.

Ruiz, a native of Mexico who joined the UA in 1983, can be credited with another notable discovery, which is that South Africa's famous gold deposits formed 3 billion years ago, about the time Earth's mantle separated from its crust.

He became head of the UA geosciences department in 1995 and dean of the College of Science in 2000. As college dean, Ruiz envisioned how the UA could develop Biosphere 2 "into a center for research, outreach, teaching and lifelong learning about Earth, its living systems and its place in the universe."

Ruiz says that he is "a great believer in universities. Universities are the national preserve of civilization, and I love being in a position to protect and enhance this environment, to encourage research and to stimulate all of those crucial relationships and interactions within this college."

Biosphere 2 Science Saturday events are included in the cost of admission to Biosphere 2.

Even better, the public can now purchase inexpensive memberships that are good for unlimited annual visits, bookstore discounts, guest passes and other benefits at Biosphere 2.

"We want people to visit Biosphere 2 often so they can take advantage of Science Saturdays and many other outreach programs we're developing," B2 Institute Director Pierre Meystre said. "We want them to visit repeatedly and follow the progress of world-class ongoing and planned science experiments. Memberships are central to our outreach mission."

More information about different types of Biosphere2 memberships is online at Biosphere 2.

Biosphere 2 is located on Oracle Road (Highway 77) at milepost 96.5. Tours are available seven days a week during visiting hours, 9 a.m. to 4 p.m. Some areas of the Biosphere 2 tour are occasionally closed because of ongoing research.

Visitors can check by telephone for more information on days they plan to visit, 520-838-6200, or online at www.b2science.org. Strollers and wheelchairs cannot be accommodated on the tour trails because the facility is structured for active research.