Nearly three-quarters of the Earth’s surface is covered by oceans, earning it the nickname of the “blue planet.” Recently, the NASA Spirit and Opportunity missions have discovered evidence that water was once present on the surface of Mars. Scientists, however, have determined that when these planets originally formed, water could not have been present. So, where did this water come from?
On Thursday, April 15, at 7:00 p.m., at the University of Delaware’s College of Marine Studies in Lewes, Adam Marsh, assistant professor of marine biology–biochemistry, will discuss the evolution of oceans in his lecture, “Where Do Oceans Come from?” Marsh’s presentation will kick off the seventh annual Ocean Currents Lecture Series, which is held once a month at the Lewes campus from April through September.
According to Marsh, the Earth formed during the birth of our solar system some 4.6 billion years ago at temperatures above 1200° Fahrenheit. At these high temperatures, only molecules with “heavy” atoms such as metals, transition elements, and silicates were stable enough to form the bulk mass of the Earth.
“The early Earth looked pretty bleak,” says Marsh. “It formed as a dry, atmosphere-free rock some 4.6 billion years ago. There were no simple molecules of carbon, nitrogen, oxygen, or hydrogen, and there was definitely no water. It was too hot for these types of compounds, and they just vaporized.”
However, it was cold enough near Jupiter, over 350 million miles from Earth, for water to form. In addition, colder temperatures enabled the formation of molecules that were more organic and biologically active, such as carbon dioxide and liquid ammonia.
In his presentation, Marsh will discuss how comets and meteors, formed near Jupiter, could have transported water to Earth while the planet was cooling. This theory of a planetary origin for Earth’s oceans is supported by several lines of evidence.
“Comets are really just dirty snowballs,” says Marsh. “They are composed of water, silicate rock, and organic molecules, which couldn’t exist at the high temperatures found on Earth during its formation. They needed the cooler temperatures near Jupiter to form.”
Marsh will conclude his talk by explaining why scientists, like himself, are interested in knowing the origin of the oceans. He notes that to understand how and why organisms have adapted and evolved to their environments, understanding the evolution of these environments also is important.
For the past nine years, Marsh has been conducting research on the early life stages of echinoderms such as sea urchins and sea stars in the Antarctic Ocean. In particular, he is interested in how these organisms can develop and grow in the extremely cold temperatures of the Antarctic water.
A member of UD’s faculty since 2000, Marsh earned his doctorate in marine ecology and environmental science in 1989 from the University of Maryland. He also has a master’s in invertebrate zoology and a bachelor’s in biology and English literature from the University of South Florida.
Last year, Marsh received a Faculty Early Career Development Award from the National Science Foundation for his work in the Antarctic. This award recognizes and supports the activities of “those teacher-scholars who are most likely to become the academic leaders of the 21st century.”
The lecture will begin at 7:00 p.m. in Room 104, Cannon Laboratory, at the Hugh R. Sharp Campus, 700 Pilottown Road, Lewes. The hour-long talk will be followed by light refreshments.
While the lecture is free and open to the public, seating is limited and reservations are required. To reserve your seat, please contact the college at (302) 645-4279.