After Years of Dimming, Earth Finally Brightens Again

Li Ming

PureInsight | June 14, 2004

[] A group of researchers at the New Jersey Institute of Technology (NJIT) and the California Institute of Technology (Caltech) have found that the Earth reflected relatively less sunlight back into space during the 80's and 90's. However, in the past three years, the Earth has started to brighten. The sunlight reflected by Earth has been increasing over the past three years.

Researchers have applied an innovative technology to monitor this change. The sunlight reflected by the Earth that hits the surface of the moon will be reflected again by the moon. This kind of "secondary reflection" is usually very weak and is often overwhelmed by the moon's own reflected light. However, scientists can detect this weak "earthshine" by monitoring the dark side (the side that does not face the sun) of the moon, and thus deduce the changes in the Earth's light reflection. Comparing these results with data provided by satellites, researchers have found that the Earth's reflection steadily decreased from 1984 to 2000. The Earth dimmed very quickly between 1995 and 1996. The dimming continued from 1997 to 2000. However from 2001 to 2003, Earth has continued to brighten and has reached the brightness level before 1995. Currently, scientists are still unclear about what has caused these changes.

[1] Science Daily: Scientists Look At Moon To Shed Light On Earth's Climate
[2] After Years of Dimming, Earth's Reflection Brightens

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