The coldest place on the Moon

BBC News : The Moon has the coldest place in the solar system measured by a spacecraft.Nasa’s Lunar Reconnaissance Orbiter ( LRO) has used its Diviner instrument since July to probe the insides of permanently shadowed craters on Earth’s satellite.Over the last few months temperatures in the lunar polar regions have changed gradually as the lunar seasons have evolved.The tilt of the Moon’s spin axis is only 1.54 degrees, and as aconsequence, lunar seasons are barely noticeable in most locations onthe Moon.However, at the north and south poles, the height of the Sun above the horizon varies by more than 3 degrees over the course of the year. This affects the percentage of sunlit regions and surface temperatures at the poles.During October Diviner observed the passage of summer solstice inthe southern hemisphere and winter solstice in the northern hemisphere.The LRO launch date was chosen so that its orbital plane passedthrough the noon to midnight plane in October, allowing Diviner to measure the extremes of polar temperatures.It found mid-winter, nighttime surface temperatures inside the coldest craters—the southwestern edge of the floor of Hermite crater , the southern edges of the floors of Peary and Bosch craters in the northern polar region—can dip as low as minus 249 °C (26 Kelvin)."One would have to travel to a distance well beyond the Kuiper belt to find objects with surfaces this cold,” said the Diviner team on their website ."The Moon has one of the most extreme thermal environments of any body in the Solar System,” said David Paige.

Photo credit: NASA/GSFC/UCLA