NASA has revealed images of a massive crater that was left by a 'mystery rocket' that smashed into the moon in March.
Newly-released photos were taken by the Lunar Reconnaissance Orbiter (LRO), NASA's robotic spacecraft currently orbiting the moon, on May 25.
They show a surprising 'double crater' roughly 92 feet (28 metres) wide near Hertzsprung crater on the moon's far side.
A US researcher discovered the rocket body hurtling towards the moon in January before it smashed into the moon on March 4, but its identity is still unknown.
It's said to be a spent rocket booster from a launch that happened years ago, but neither China nor the US will claim responsibly for it.
Mark Robinson, a professor of Earth and space exploration at Arizona State University, said the item weighed about four tons and was travelling at 5,700 miles per hour prior to impact.
Images of the resulting crater, take by the Lunar Reconnaissance Orbiter Camera (LROC), a system of three cameras mounted on the LRO, were shared by NASA.
'The identity of the rocket body remains unclear,' NASA said.
'The double crater was unexpected and may indicate that the rocket body had large masses at each end.'
Since the origin of the rocket body remains uncertain, the double nature of the crater may help to indicate its identity, the space agency said.
Surprisingly, the crater is two craters – an eastern crater 59 feet (18 metres) in diameter, superimposed on a western crater 52 feet (16 metres) in diameter.
NASA said no other rocket impacts on the moon in history have caused a double crater, although there are bigger human-caused impact craters on the moon.
Impact craters made during four of the Apollo missions in the 1970s were substantially larger (greater than 115 feet) than each of the double craters.
It was back in January that the 'mystery rocket' was initially identified by Bill Gray, an independent researcher and developer of the astronomical software Project Pluto.
'I am in no way an expert on what happens in high-speed impacts like this, except to know that they can have some very strange, non-intuitive results,' he said.
Back in January prior to impact, Gray thought the object was the booster from a SpaceX rocket launch in February 2015, which sent a weather and Earth observation satellite named DSCOVR into orbit for NASA.
However, NASA said its analysis showed that the object was likely the booster rocket from China's Chang'e 5-T1 mission launched in October 2014 from Xichang Satellite Launch Center, Xichang, China.
This was denied by a Chinese foreign ministry spokesman, who said China's aerospace endeavours are 'always in keeping with international law'.
China launched the uncrewed Chang'e 5-T1 spacecraft to the moon on a Long March 3C rocket, a three-stage Chinese rocket with two strap-on liquid rocket boosters.
The objective of the mission was to test the ability of the spacecraft's capsule to re-enter Earth's atmosphere.