We should remember that... of the 6,000 stars [that] the average human eye could see in the entire sky, probably not more than thirty – or one-half of one percent – are less luminous than the Sun; that probably, of the 700-odd stars nearer than ten parsecs, at least 96% are less luminous than the Sun. There is not even ONE real yellow giant – such as Capella, Pollux, or Arcturus – nearer than ten parsecs¹ and only about four main sequence A stars.
– Dutch astronomer Willem Jacob Luyten (1899 - 1994)

The closest star to us is, of course, our own Sun. It's unusual because it's a solitary yellow dwarf, while most of the stars nearby are in binary or even multiple systems. What makes our star really special though, is that it provides the energy for the only life in the Universe that we know of.

Less Than Ten Light Years

The nearest star to the Sun is Proxima Centauri (also known as alpha Centauri C), which is a red dwarf, and is 4.2 light years² distant. It has two stellar companions, the yellow dwarf Rigil Kentaurus (alpha Centauri A) and an orange dwarf, alpha Centauri B. They take up joint second place in our list, at 4.35 light years.

Barnard's Star, a red dwarf, is just under six light years away. Next comes Wolf 359, another red dwarf. Yet another red dwarf, Lalande 21185, was thought to be the fourth-closest star when its co-ordinates were published by Joseph-Jérôme Lefrançais de Lalande (1732 - 1807) in 1801. This was before Barnard's Star and Wolf 359 were discovered. Lalande 21185 cannot be seen by the naked eye because at 7th magnitude it is too dim; however, it counts as sixth-closest to the Sun at 8.3 light years.

The seventh-closest is a star most denizens of Earth would recognise: Sirius (alpha Canis Majoris), with eighth place taken by its companion Sirius B, sometimes referred to as 'the Pup'. Sirius B is classified as a white dwarf, but it is one of the biggest known: in fact, its mass is comparable to that of our own Sun.

Completing the top ten stellar neighbours are BL Ceti, a red dwarf flare star, and its binary partner UV Ceti³, which are 8.7 light years away from our Sun. Flare stars unleash bright flashes of light as well as streams of charged particles. Some of the stars studied have flares of such enormous intensity that they can increase the brightness of the star by up to 10%. The flares are only brief, like a camera flash, but would be detrimental to any nearby planets.

Next in line is Ross 154, one of many discovered in 1925 by American astronomer Frank Elmore Ross (1874 - 1960). Ross 154 is a UV Ceti-type flare star 9.7 light years distant, and is the last of the stars within ten light years of our Solar System.

Between Ten and Twelve Light Years

At 10.3 light years is another one on the Ross catalogue: Ross 248, a red dwarf flare star. Due to the wide variety of periods that this star flares (4.2 years, 120 days, and five other catalogued outbursts between 60 and 291 days apart), astronomers suspect that Ross 248 has an undetected companion which is causing the erratic flaring. Next on is Epsilon Eridani, which has a dust disc⁴ and a suspected extrasolar planet system, the closest detected up to the time of writing, 2012. The two candidate planets are not thought to be hospitable to life (as we know it) because their proposed orbits are so far from the star. If the planets do exist, they are likely to be frigid worlds like our outermost planet Neptune⁵.

The French astronomer Nicolas Louis de Lacaille (1713 - 62) went on a 1751-4 expedition to the Cape of Good Hope, effectively a blank canvas sky for him to map. Using the planet Mars as a point of reference, his observations were the foundations for working out the lunar and solar parallax. Finding himself somewhat of a celebrity upon his return to Paris, de Lacaille hid from public attention in Mazarin College, writing up his findings. Barely taking care of himself, de Lacaille suffered from gout and was prone to over-working to the point of exhaustion. Unfortunately his catalogue, Coelum Australe Stelliferum, which described 14 new constellations and 42 nebulous objects among almost 10,000 southern stars, wasn't published until after he died at the age of just 49 years. One of those stars, Lacaille 9352, ranks as the 14th-closest to our Sun at 10.7 light years distance.

EZ Aquarii is a triple star system situated at 11.3 light years away. EZ Aquarii A, B and C are all red dwarfs, and they may all be flare stars; however, not much is known about the smallest component (B). They are so dim (magnitude +13) that specialist equipment is required to view them. The system was labelled Luyten 789-6 by Dutch astronomer Willem Jacob Luyten, whose interest in astronomy had been sparked by viewing the predicted return of Halley's Comet in 1910, as an 11-year old schoolboy. In 1925 Luyten lost an eye in an accident but this tragedy did not wreck his chosen career. He was already working at the Harvard College Observatory, having been offered a post by the new director Harlow Shapley, whose own profile had been raised due to his participation in the Shapley-Curtis Debate of 1920. Luyten 'observed and measured more stellar images than anyone else', according to his biography at the National Academy of Sciences. He took up teaching at the University of Minnesota in 1931, and when he retired in 1967 he was given the title of Astronomer Emeritus which he held until his death at the ripe old age of 95.

Procyon is a binary system which registers at +0.3 magnitude. The system consists of a yellow-white main sequence subgiant star, Procyon A, and a white dwarf companion, Procyon B, which was detected by Arthur von Auwers in 1862.

The binary system 61 Cygni has two orange dwarf components of 6th magnitude at 11.41 light years away. Its distance was the first to be measured of any star. These two stars claim joint 21st place in our list of close stellar neighbours. Another pair of red dwarf stars, Struve 2398 A and B, positioned at just 11.5 light years distant, are the next nearest. They were studied by Russian-German astronomer Prof Friedrich von Struve (1793 - 1864), director of the Dorpat Observatory (now the Tartu Observatory) in Estonia, who listed them in his Catalogus novus stellarum duplicium (Double Star Catalogue) of 1827.

Groombridge 34 are twin variable red dwarfs. Newly-discovered variable stars are given upper case capital letters, so Groombridge 34 A and B are also known as GX Andromedae and GQ Andromedae respectively. The Epsilon Indi system is fascinating because it contains the closest-known brown dwarfs. Brown dwarfs are approximately the same size as Jupiter⁶, but their mass is at least ten times greater, possibly up to 50×. These bodies are neither star nor planet, but 'failed' stars. Other titles have been proposed, as it's hardly encouraging to keep referring to them as 'failed stars'. Suggestions so far include planetar (which sounds like something from the science fiction genre) and substar (that 'sub' prefix isn't much of an improvement). Since 2004, planets have been discovered orbiting brown dwarfs, (although not, as yet, in the Epsilon Indi system), so their profile has been raised. Hopefully they are in line for a better class in the future.

DX Cancri is a solo red dwarf flare star which expands to five times its usual brightness during flare activity. It is thought by some astronomers that DX Cancri is a member of the Castor Moving Group which was suggested in 1990 by JP Anosova and VV Orlov at the Astronomical Observatory in Leningrad State University, Russia. A moving group is the term for a collection of stars which share the same origin. Although they are not gravitationally bound to each other they are on the same path on their journey through the galaxy, like an unravelled, stretched-out cluster. The Castor Moving Group is named after the luminary of Gemini, and includes the stars Alderamin (alpha Cephei), Fomalhaut, Vega, psi Velorum and Zubenelgenubi (alpha Librae).

Tau Ceti is one of the few nearby stars which are visible to the naked eye, albeit in the dim constellation Cetus, the Whale. Tau Ceti shot to fame in 1960, when Frank Drake launched Project Ozma, aiming to detect non-natural signals from space. Drake chose two stars which were similar to our Sun, Tau Ceti and Epsilon Eridani, for his project, which evolved to become SETI, the Search for Extra-terrestrial Intelligence. In December 2012, it was announced that five planets had been discovered orbiting Tau Ceti, with one of them possibly residing in the system's habitable zone.

Red dwarf GJ 1061 in the southern constellation Horologium is the last of the stars within 12 light years. GJ 1061 is really small, even on the dwarf star scale: it registers just over ten percent of the Sun's mass. It is so dim (+13 mag) that you'd need a decent-sized telescope to view it, but just in case you ever get the opportunity, its co-ordinates are 03h 36m RA, −44° 30' 46" Dec. During August 2019, the Red Dots project of detecting terrestrial planets around nearby red dwarf stars announced the discovery of three Earth-like planets belonging to this system, two of them residing within the habitable zone of the star.

Nearby Stars in Fantasy and Science Fiction

Stars which are close to our own Solar System have inspired imaginative writers going back hundreds of years. Here is just a sample:

• Proxima Centauri: the 1990s TV series Babylon 5 featured the planet Proxima III, which hosts an Earth Alliance colony.

• Alpha Centauri A: prolific author Isaac Asimov wrote about the water world Alpha of the Alpha Centauri A system in the Foundation and Earth book of his Foundation series.

• Alpha Centauri B: Witburg is a rocky planet orbiting Alpha Centauri B in the 2002 online role-playing game Earth & Beyond.

• Barnard's Star: Timemaster, a 1992 novel by Robert L Forward, bases its plot in the Barnard's Star system.

• Wolf 359: Star Trek fans will recognise Wolf 359 as the system where Starfleet's armada was practically wiped out by the hive-minded Borg.

• Lalande 21185: in the 1951 novel Rogue Queen penned by L Sprague de Camp, the planet Ormazd which orbits Lalande 21185 is investigated by Earth's space authority.

• Sirius: Micromégas is one of the earliest known science fiction stories, it was written in 1752 by François-Marie Arouet (better known by his pen name Voltaire). The Micromégas of the story was an extremely tall⁷ alien visitor to Earth who hailed from one of the planets in the Sirius system.

• Sirius B: in Seed of Light, a 1959 novel by Edmund Cooper, the Sirius A star is barren but Sirius B has a hospitable planet, Sirius B III, out of its five attendant worlds. The plot revolves around the people sent there to save the human race after the Earth has been devastated.

• BL Ceti: Larry Niven wrote A Gift From Earth in 1968, a part of his Known Space collection of multiple works. The plot involves the twin red dwarf stars BL Ceti and UV Ceti, which are important signposts for the eventual destination.

• UV Ceti: a space station called Eldorado, part of the 'Great Circle' route, is based at UV Ceti in the 1981 story Downbelow Station by CJ Cherryh.

• Ross 154: the planet Tei Tenga in the Ross 154 system is where the United Aerospace Armed Forces (UAFF) had a couple of military research bases in the video game Doom.

• Ross 248: Diadem is an icy world in orbit around Ross 248 in Alastair Reynolds's story Glacial. Following a failed attempt at human colonisation, an investigation a century later reveals that the planet is sentient and it uses cold-blooded annelids, burrowing through its ice-mantle, to 'think'.

• Epsilon Eridani: Les Grognards d'Éridan (The Napoleons Of Eridanus), written by French author Claude Avice in 1970, features a detachment of soldiers from the Napoleonic era who are abducted by aliens and transported to the Epsilon Eridani system to fight their battles for them. Also, Epsilon Eridani was the parent star of the planet Reach in the extremely successful Xbox game Halo: Reach.

• Lacaille 9352: in the fictional universe of the Hyperion Cantos dreamed up by Dan Simmons, the inhospitable planet Sibiatu's Bitterness orbits the star Lacaille 9352.

• Ross 128: Across the Sea of Suns, written in 1984 by Gregory Benford, features a race of alien aquatic creatures which live under the ice-mantle of the frozen world Pocks, a member of the Ross 128 system.

• EZ Aquarii A, B and C: the character Sheldon in The Big Bang Theory regularly lists 'the closest stars to me' when ascending and descending stairs. Once, in disguise, he spoke the words 'EZ Aquarii B, EZ Aquarii C,' while passing Amy on the stairs, and was dismayed that she recognised him.

• Procyon A/B: His Master's Voice was written by Polish author Stanislaw Lem in 1968. This book focuses on the attempts by highly intelligent Earthlings to understand a message from the Procyon system.

• 61 Cygni: The region surrounding 61 Cygni is known as the 'Darkling Zone' in the popular TV series Blake's 7.

• Groombridge 34: The Groombridge 34 system features in the Halo series of Xbox games.

• Epsilon Indi: New New York on Epsilon Indi III has a portal to the Earth, via a created wormhole, in the 1996 Starplex book by Robert J Sawyer.

• Tau Ceti: Time for the Stars, written in 1956 by Robert A Heinlein, explores the telepathic bond between twins over the vastness of space. Tau Ceti III, in the Star Trek universe, is a hospitable M-class planet. One of the bountiful fruits which grows there is the Kaferian apple. While they can be eaten raw, they are much more tasty stewed with Talaxian spices and served in a pie, as recommended in the vegetarian options at Quark's Bar on the space station Deep Space Nine.