The moon is not the colour you think it is

New images from Juice mission reveal the lunar surface may be more colourful than many believe

The Moon is not only grey but also has shades of red and blue, spacecraft images have suggested.
New images from the Juice mission to Jupiter have revealed the Moon, typically thought to be grey, may be more colourful than many believe.
The spacecraft is on a convoluted path to the Solar System’s largest planet and will arrive in 2031 after detours past the Moon, Earth and Venus.
Cameras on the pioneering spacecraft which are designed to monitor the health of the machine have been used to take photos of the lunar surface.
In the images the pockmarked surface is accompanied with a range of colours, with the pole looking more rouge and the equatorial region appearing teal.
Andrew Coates, a professor of physics at the UCL Mullard Space Science Laboratory, is the co-investigator of Juice’s main camera, called Janus.
He said the colouration is likely a combination of genuine changes in ground pigmentation, sunlight from the Sun altering the appearance and some calibration issues from the cameras.
“With the Moon, you do get differences in the mare and the highlands areas. Subtle colour differences can occur due to slight differences in composition,” he said.
“There are subtly different real hues from lunar basalts (blueish) and lava flows (reddish), and lots of colour in some lunar samples. It does look like there are some apparent real colour differences.
“I do wonder if some of this may be due to calibration as calibration of instruments sometimes takes a little while to do. You do also get, because of the different angle of the Sun to the surface, a slight difference in hue from that as well.
“It’s worth saying that the Janus cameras should get better images and with better calibration so we’ll probably have to wait until September to know how real this is — but nevertheless it is interesting to see.”
However, the European Space Agency (ESA) had a different perspective on the colourful images, instead seeing the images in more black and white terms.
“In the images we can distinguish three colours: darker grey, light grey and even lighter grey,” a spokesman told The Telegraph.
“The darker regions that we can see in the images, mainly the Mare Fecunditatis and Mare Nectaris, are related to terrains which were resurfaced by volcanic activity (basaltic composition).
“Basalts are less reflective compared to the other brighter terrains (typically called ‘highlands’, mainly composed of anorthosites), and therefore are darker in the image.
“Brighter aligned terrain structures – lighter grey – are typically crater ejecta, which are fresher material resulting from an impact.”
An on-board monitoring camera took the latest images but Janus, a more sophisticated camera which will be used to gather scientific data, is also taking high-resolution imagery during the flybys. 
However, the Janus images have not yet been released and are expected to be presented at a Berlin conference in September.
Juice will look for signs of life on the Jovian moons, including Ganymede, Europa and Callisto, which astronomers say could host alien life.
Its first flyby since its launch in April 2023 took place on Monday and marked the first time a spacecraft has ever done a flyby of both the Moon and the Earth in one trip.
ESA said on Tuesday that the flyby manoeuvre had gone perfectly, with the “flawless manoeuvre” needing no alterations from on-board thrusters.
It will now head towards Earth and be at its closest at about 11pm BST where Earth’s gravity will slow Juice down as it careers towards Venus for a flyby in August 2025.
Its convoluted path is intended to generate enough momentum from gravitational slingshots for the craft to reach Jupiter.
The next flybys of Earth will be in September 2026 and January 2029 before Juice gathers enough momentum to head into the outer Solar System and arrives in Jovian orbit in July 2031.
“Excitingly, Juice will be going past the Earth tonight as well because it is doing this double Moon and Earth flyby which is a real first,” added Prof Coates.
“It is using the gravity of both to tweak the trajectory a very little bit, obviously in this case we are slowing the spacecraft down rather than speeding up.”
Prof Coates pointed out that with Juice using the Earth’s gravity to slow down, Earth will actually gain some energy from Juice’s flyby.
“It’s actually giving a very little bit of energy to both the Moon and the Earth,” he joked.
“It is only a very small amount of energy but it’s good of Juice to give a little bit back.”