NANJING, April 10 (Xinhua) -- Research into lunar meteorites by a team of Chinese scientists has provided new evidence to support the giant-impact theory, which argues that the moon was formed after a Mars-sized body impacted the Earth 4.5 billion years ago.
Scientists with the Purple Mountain Observatory conducted research on three lunar meteorites from the U.S. space agency NASA and found chlorine isotopic fractionation, which only occurs in ultra-high-temperature and ultra-high-energy conditions, such as a giant collision between astronomical bodies.
Wang Ying from the research team said chlorine isotopic fractionation was a process in which chlorine-35, an isotope of chlorine, easily evaporates under high temperatures while the heavier chlorine-37 can better stand the heat.
The discovery of the phenomenon in lunar meteorites demonstrates that the moon originated from a giant impact, Wang said.
The giant-impact hypothesis has been the prevailing theory on the origin of the moon. It suggests the collision between the Earth and a Mars-sized body created a large debris disk that eventually formed the moon.
"The giant-impact hypothesis gives answer to many questions, such as the moon's rotation speed and the relatively large size of the moon compared with the Earth," said Xu Weibiao, another scientist from the observatory.
"Besides, lunar rocks retrieved by astronauts have the same oxygen isotope ratio as the Earth. In other words, the two bodies share the same set of DNA," Xu said.
The research started in 2011 and the result was published on Scientific Reports in early April.