The Dark Side of the Moon Gets Just as Much Sunlight, Here Is What the Lunar Farside Actually Looks Like

The phrase "dark side of the moon" has nothing to do with sunlight. The moon rotates on its axis once every 27.3 days, exactly the same time it takes to orbit Earth. This synchronisation, called tidal locking, means the same hemisphere always faces us and the opposite hemisphere always faces away. Both sides receive roughly equal amounts of solar radiation over the course of a lunar day, which lasts about 29.5 Earth days. The farside bakes in full sunlight for two weeks, then freezes in darkness for two weeks, just like the nearside. The word "dark" in the popular phrase originally meant unknown, not unlit. Humans had simply never seen it.
That changed on October 7, 1959, when the Soviet probe Luna 3 swung around the moon and transmitted the first grainy photographs of the farside. What scientists saw surprised them. The surface looked fundamentally different from the side we see every night.The nearside of the moon is covered in vast dark plains called maria, ancient lava flows that cooled billions of years ago and give the moon its familiar face. The farside has almost none of them. Where the nearside is roughly 31% maria, the farside is less than 2%. Instead, the farside is dominated by highlands: a heavily cratered, pale, mountainous terrain that looks like it absorbed every major impact the early solar system could throw at it without the volcanic resurfacing that smoothed out much of the nearside.
The reason for this asymmetry is still debated. One leading hypothesis, developed by researchers including those publishing in the journal Nature in 2014, suggests the moon's crust on the farside is significantly thicker, up to 10 kilometres thicker in places, which prevented magma from breaking through after the Late Heavy Bombardment around 4 billion years ago. The South Pole-Aitken Basin on the farside is one of the largest confirmed impact craters in the entire solar system: roughly 2,500 kilometres across and 8 kilometres deep. If you stood at its centre, the crater rim would be below your horizon.No mission landed on the lunar farside until January 3, 2019, when China's Chang'e 4 spacecraft touched down inside the Von Kármán crater, itself sitting within the South Pole-Aitken Basin. The reason no one had done it before is a genuine engineering problem: the farside has no direct line of sight to Earth, so a lander cannot communicate directly with ground stations. China solved this by first placing a relay satellite, Queqiao, at the Earth-Moon Lagrange point 2, roughly 65,000 kilometres beyond the moon, to bounce signals between Chang'e 4 and Earth. The rover Yutu-2, deployed from Chang'e 4, is still operating and has covered more than 1,900 metres of farside terrain as of its last reported status, the longest operational distance by any lunar rover.
The Chang'e 4 mission detected a mantle material on the surface that scientists believe was excavated by the ancient impact that formed the South Pole-Aitken Basin, offering a direct sample window into the moon's interior composition without drilling.ISRO's Chandrayaan-3 landed near the lunar south pole on August 23, 2023, making India the first country to achieve a soft landing in that region. The south pole sits at the boundary of the nearside-farside divide and is scientifically valuable for a separate reason: permanently shadowed craters there trap water ice, confirmed by Chandrayaan-1's Moon Impact Probe and NASA's LCROSS mission. Chandrayaan-3's Pragyan rover detected sulphur, iron, oxygen, and other elements in the south polar soil using laser-induced breakdown spectroscopy, data that feeds directly into understanding how the moon's surface chemistry varies from the equatorial nearside to the poles. A future ISRO mission to the farside itself would require the same relay satellite solution China deployed, a logistical challenge ISRO has acknowledged in its long-range mission planning.The farside of the moon is the quietest place reachable by any spacecraft humans have ever built. Earth generates an enormous amount of radio frequency interference, from mobile networks, satellites, and broadcast towers, that contaminates ground-based radio telescope observations at low frequencies below 30 MHz. The moon's bulk blocks all of that noise from reaching the farside. A radio telescope array placed on the lunar farside could observe the universe at frequencies that are essentially inaccessible from Earth, including the 21-centimetre hydrogen line redshifted from the cosmic dark ages, the period before the first stars formed. NASA's Lunar Surface Electromagnetics Experiment, deployed as part of the Artemis programme, is an early step toward characterising the farside radio environment. Several proposals for a farside radio array exist, though none have moved beyond the concept stage.

The moon people called dark turns out to be the most scientifically coveted piece of real estate in the inner solar system, not for what it hides from us, but for what it hides from everything else.