Astronauts on board the International Space Station (ISS) have spotted what has been described as “two mysterious dark circles” in the ice of Lake Baikal in Russia. Some aspects of “odd blemishes” that the astronauts noticed in April 2009 defy explanation and hence mysterious.
According to scientists, the two circles are the focal points for ice break-up, and may have been caused by “upwelling” of warmer water in the lake.
The dark color of the circles is the result of thinning of the ice, which usually happens into June.
Upwelling, the scientists say, is not unusual in some relatively shallow areas of the lake where hydrothermal activity has been detected, such as where the circle near the centre of the lake is located. In fact, circles have been noticed in that area earlier – in 1985 and 1994, but they were not as marked as it was this time around.
It is the location of the circle – near the southern tip of the lake, where water is relatively deep and cold – that puzzles the scientists most.
The interesting thing is that the lake in question, Lake Baikal in Russia, is the largest lake by volume and the deepest (5,370 feet at its deepest point) as well as one of the oldest in the world-–- about 25 million years old.