Staring up at the Moon with the naked eye, we can forgive early astronomers for assuming the dark patches spread out over its surface were seas - or 'maria' as they were named, after the Latin word for seas. Informed by centuries of ever-improving observations and over 60 years of space exploration, we now know the maria are not seas but rather vast expanses of volcanic basalt that erupted over the lunar surface several billion years ago.
The Moon is in fact very dry: more so than any desert on Earth. Yet despite that, on 23 August 2023 the Indian Space Research Organisation's Chandrayaan-3 mission successfully deployed its lander and rover near the lunar south pole in search of water.
So why search for water in such a dry location? Although there is no liquid water on the Moon, water is present in the form of ice trapped between grains in the lunar soil and incorporated into minerals and glassy beads produced by impacts. The potential for such hidden water was first suggested by remote observations of the surface, and later confirmed by NASA's LCROSS mission, which in 2009 fired an empty rocket stage into a crater on the lunar surface and identified ice in the plume of material flung up from the crash site. Further observations of the surface by the likes of the NASA and German Aerospace Center's SOFIA telescope have since suggested the south polar region of the Moon in particular may host far more water than we ever imagined. As much as 100-400mg of water (about one raindrop) may be present in each kilo of soil.
While this may seem a small amount, it has prompted several space agencies to propose lunar surface missions and instruments to find and characterise lunar water over the next decade.
PROSPECTing for water
This story is from the December 2023 edition of BBC Sky at Night Magazine.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 8,500+ magazines and newspapers.
Already a subscriber ? Sign In
This story is from the December 2023 edition of BBC Sky at Night Magazine.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 8,500+ magazines and newspapers.
Already a subscriber? Sign In
Unearthing galaxies in the archives
Comparing old Hubble data to today is revealing distant active galaxies
Voyager 1 is back online and exploring the unknown
An interstellar rescue brings the venerable spacecraft back after months out of action
When Haydn met the Herschels
Jonathan Powell on how the astronomer siblings inspired the famous composer
A quicker way to colourise your narrowband frames
Create a bicolour image in Siril using data from just two narrowband filters
Manhattanhenge
New York's urban island of Manhattan, with its gridiron street layout, sees summer Suns set neatly between skyscrapers. Jamie Carter explains the phenomenon
A very British eclipse
In 1927, Britain experienced its first total solar eclipse since 1724. Mike Frost looks at how, like 8 April 2024's US spectacle, eclipse fever swept the nation
The spirit of the eclipse
Eclipse chaser Yvette Cook reports on what it was like in the path of totality in Texas during 8 April's Great American Eclipse
Cosmic rays
In part two of our series, Govert Schilling looks at cosmic rays, the high-energy particles that bombard Earth from space
Stones of the SOLSTICE
Jamie Carter explores 12 ancient stones, tombs and temples across the world that align with the Sun at the solstice
Surfing spacetime with LISA
A new era of gravitational wave astronomy is on its way as the ambitious upcoming LISA space mission joins a host of huge detectors on Earth. Charlie Hoy explains