- Dust movements were detected by a small machine, invented by University of Western Australia adjunct professor Brian O’Brien in 1966
- High-energy sunlight positively charges the dust particles, pushing them away from each other, lifting the dust three feet above the moon’s surface
- When ‘horizon brightening’ occurs, the effect is an eerie glow
Experts have finally solved the mystery of the moon’s eerie glow, which has baffled scientists for more than 50 years.
They say ‘horizon glow’ – a bizarre glow occurring on the Moon’s western horizon just after sunset – is caused by two newly-discovered phenomena linked to dust movements on the moon’s surface.
They are ‘sunrise dust storms’ and ‘horizon brightening,’ which when combined, result in the glow.
The bizarre glow on the moon’s western horizon (pictrued) , known as ‘horizon glow’, has been linked to dust particle movements just after sunset. High-energy sunlight positively charges the dust particles, pushing them away from each other, lifting the dust a metre above the moon’s surface
Horizon brightening is when the dawn horizon becomes one to four per cent brighter than sunlight at the end of sunrise.
The two phenomena were detected by a small machine, invented by University of Western Australia professor Brian O’Brien in 1966.
The ‘dust detector’ was mounted three feet (one metre) above the moon’s surface a few years after it was invented and the data it collected is still being analysed.
‘It found that sunrise dust-storms had resulted from the Apollo 12 mission rockets freeing up dust particles on the moon’s smooth surface and then sunrise lifting them to this height,’ he said.
The dust detector (pictured) was switched off in 1976 but the data it recorded was only recently collated, showing the dust did in fact hover about three feet off the ground, rather than kilometres above the surface
The high-energy sunlight positively charged the dust particles, pushing them away from each other, lifting the dust three feet (one metre) above the moon’s surface.
‘The dust continued to seamlessly scatter extra light into the solar cell of the dust detector, which we discovered and reported as horizon brightening by about one to four per cent more than direct sunlight,’ he said.
Professor O’Brien developed a model explaining sunrise dust storms and how they create ‘horizon brightening’.
‘Our “horizon brightening” is the sunrise equivalent of the post-sunset horizon glow,’ he said.
Professor O’Brien said it was important to understand characteristics of dust, as it has caused overheating and failure of many instruments and machines on the moon’s surface, including possibly China’s lunar rover Yutu to stall last year.
The dust detector was switched off in 1976, but the data it recorded was only recently collated, showing the dust did in fact hover about three feet (one metre) off the ground, rather than miles above the surface as previously predicted.
Earlier this year, Nasa’s sophisticated dust detector on the Lunar Atmosphere and Dust Environment Explorer (Ladee) which is orbiting the moon, confirmed there’s no evidence of moon dust at altitudes between two and 155 miles (three to 250km).
