ice-covered

The 38 mushers will trace a course across two mountain ranges, the frozen Yukon River and along the ice-covered Bering Sea.

"Methane plays a major role in warming our planet. The challenge with methane is that it is a super-potent greenhouse gas and increasing emissions will accelerate climate warming. From a global perspective, we can measure how much is emitted into the atmosphere and, roughly speaking, where the methane comes from, using the isotopes found in the atmospheric methane. And for now, the contribution of methane from ice-covered regions on our planet, including ice sheets and glaciers, isn't increasing," explains Jesper Riis Christiansen.

A revolving, ice-covered stage allows the actors to skate while remaining stationary in front of the audience.

Bystanders called 911 on Thursday after the 65-year-old Traverse City man fell through ice-covered Arbutus Lake, state police said.

"Our analyses predict that these 17 worlds may have ice-covered surfaces but receive enough internal heating from the decay of radioactive elements and tidal forces from their host stars to maintain internal oceans," said Dr. Lynnae Quick of NASA's Goddard Space Flight Center in Greenbelt, Maryland.