Auriga
“The Charioteer” · Northern · best around February evenings
Real star positions and magnitudes (HYG database via D3-Celestial, BSD-3). Lines are the conventional stick figure; north is up.
The story
A pentagon crowned by golden Capella, the most northerly first-magnitude star — actually two pairs of suns. The 'Kids', a tight triangle of stars beside it, have been the charioteer's goats for 2,500 years. Three bright Messier clusters (M36, M37, M38) ride its Milky Way band.
How to find it
High overhead on winter evenings, above Orion and Taurus.
✦ What lives inside it
- Clusters M36, M37, M38
The deep dive
Researched for the Atlas from Wikipedia — Auriga (43,728 characters read) · updated Sep 20, 2026
01 Capella's surprising double nature
Capella looks like a single golden-yellow point of light, but it is actually two yellow giant stars locked in a tight orbital embrace. Both components are surprisingly similar: the primary carries a mass of 2.47 solar masses and a radius of 11.87 solar radii, while the secondary masses 2.44 solar masses and spans 8.75 solar radii. Together they shine at a combined luminosity of 160 times the Sun — 90 solar luminosities from the primary and 70 from the secondary. Despite their grandeur, the pair are separated by only 110 million kilometres, roughly 75 percent of the Earth–Sun distance, which is why they cannot be split by any telescope. Their orbital period of 104 days was pinned down in 1919 by J. A. Anderson using the 100-inch telescope at Mt. Wilson Observatory, two decades after the binary nature itself was revealed spectroscopically at Lick Observatory in 1899. Perched 11,000 astronomical units from this main pair sits a distant companion, Capella H — itself a pair of red dwarf stars — lurking just 0.17 light-years away, making Capella a gravitationally complex family of at least four stars.
02 Epsilon Aurigae: a mystery that took centuries Deeper
Epsilon Aurigae holds a record that no other known star can match: it is the longest-period eclipsing binary currently known, dimming on a cycle of 27 years. Its last minima ran from 1982 to 1984 and again from 2009 to 2011. At maximum the system shines at magnitude 3.0, but it lingers near magnitude 3.8 for roughly a year during each eclipse. The primary is a white supergiant with an absolute magnitude of −8.5 and a staggering luminosity of 200,000 solar luminosities — which is why it appears so prominent despite a disputed distance of somewhere between 2,170 and 4,600 light-years. The companion remains poorly understood; it may itself be a binary star shrouded within a large dusty disk. The first eclipse was observed in 1821, but its variable nature was not confirmed until the eclipse of 1847–48. Since then, astronomers have proposed many theories about the eclipsing body. Adding to the puzzle is a separate, non-eclipsing fourteenth-magnitude companion separated by 28.6 arcseconds, discovered in 1891 by Sherburne Wesley Burnham at Dearborn Observatory and located about 0.5 light-years from the primary.
03 A nova that kept astronomers guessing
On January 23, 1892, Scottish amateur Thomas David Anderson spotted a new star in Auriga at magnitude 5.0 — but photographic plates later showed the object had already reached naked-eye visibility by December 10, 1891, brightening by a factor of 2.5 between December 11 and December 20 to peak at magnitude 4.4. This was T Aurigae, or Nova Aurigae 1891. It then faded slowly through early 1892, only to brighten again in August back to magnitude 9.5, where it held steady until 1895. By 1903 it had sunk to magnitude 14, and by 1925 it had settled at its current magnitude of 15.5. The nova's spectrum initially showed material rushing toward Earth at high speed, but by August 1892 it resembled a planetary nebula. Edward Emerson Barnard observed it at Lick Observatory and found a disc-shaped object with clear nebulosity spanning 3 arcseconds; by 1943 the shell had expanded to 12 arcseconds across. T Aurigae is classified as a slow nova similar to DQ Herculis, and like that object it is a very close binary with a period of just 4.905 hours, including a partial eclipse lasting 40 minutes.
04 The Milky Way's edge runs right through Auriga Deeper
Auriga contains one of astronomy's more intriguing coordinate landmarks: the galactic anticenter, located about 3.5 degrees east of Beta Aurigae. This is the point on the sky directly opposite the Galactic Center, marking the outermost edge of the galactic plane as seen from the Solar System. When you look in this direction, you are looking away from the dense, luminous core of the Milky Way toward the thinner, less populated outer reaches; the star density and diffuse glow are noticeably lower than when gazing toward Sagittarius. Threading through the constellation are two major star-forming spiral arms: the Perseus Arm and the Orion–Cygnus Arm. Their presence explains why Auriga is so extraordinarily rich in open clusters — M36, M37, and M38 are just the brightest examples within reach of binoculars. Dust bands belonging to these outer spiral arms are also visible, creating dark lanes that contrast against the bright stellar background. This combination of a prominent anticenter and multiple spiral-arm crossings makes Auriga a rewarding region for anyone interested in the large-scale architecture of our galaxy.
05 The Charioteer across world cultures
Long before Greek astronomers drew a charioteer, Mesopotamian sky-watchers recorded the same stars as a constellation called GAM — possibly representing a scimitar or a shepherd's crook — and the association with goat-herding persisted into Greek tradition. Chinese astronomers organised the same stars into several separate figures: Wuche, the five chariots of the celestial emperors and a symbol of the grain harvest, was built from Alpha, Beta, Theta, and Iota Aurigae together with Beta Tauri. The stars of the Haedi — Epsilon, Zeta, and Eta Aurigae — formed part of Sanzhu, representing poles for tethering horses. Meanwhile, in the Marshall Islands, Capella was Ligedaner, the mother of all stars, whose sons raced across the sky to become King of the Stars. In Hawaii, Capella was known as Hoku-lei, meaning "star-wreath," and named one of the wives of the Pleiades. The indigenous Pawnee of North America independently identified the same pentagon of bright stars — Alpha, Beta, Theta, Iota, and Gamma Aurigae — as a distinct pattern, and California and Nevada peoples recorded the bright curve in crescent-shaped petroglyphs. Capella also served as a calendrical marker for the Aztecs, with a heliacal-rising alignment at the Late Classic site of Monte Albán.
06 Inuit star-lore and celestial navigation
Among the Inuit, Capella and Menkalinan were incorporated into a constellation called Quturjuuk, meaning "collar-bones," which also included Castor and Pollux from Gemini. Quturjuuk served a practical function beyond mythology: its rising in the sky signalled that the constellation Aagjuuk was about to appear. Aagjuuk, made up of Altair, Tarazed, and sometimes Alshain in Aquila, represented the dawn following the winter solstice and was described as an incredibly important constellation in Inuit tradition. Aagjuuk was used actively for both navigation and timekeeping at night, making the appearance of Quturjuuk effectively a celestial alarm clock that alerted travellers and hunters to prepare for a key navigational event. This chain of stellar signalling — one constellation announcing the imminent arrival of another — illustrates how Inuit sky knowledge was embedded in practical survival rather than purely in storytelling. The fact that Auriga's two brightest stars form part of this system underlines how the constellation's prominence in northern skies made it a natural reference point for Arctic peoples living at latitudes where Auriga's stars climb high overhead.
07 Three open clusters for every aperture
M36, M37, and M38 form a trio of Messier open clusters visible in binoculars under suburban skies, yet each rewards a larger telescope quite differently. M36 is the smallest and most concentrated of the three: about 60 stars in a span of 14 light-years, sitting 3,900 light-years away and glowing at magnitude 6.0. Most of its stars are rapidly rotating B-type stars, and a central knot anchored by the double star Struve 737 stands out at 12 arcminutes across. M37, discovered by Charles Messier in 1764, is the richest and brightest of the three: 150 stars spread across roughly 25 light-years at 4,200 light-years' distance, shining at magnitude 5.6 and spanning 23 arcminutes. An orange giant at its center catches the eye immediately, and Charles Piazzi Smyth described the wider star field as "strewed with sparkling gold-dust." The stars of M37 are approximately 200 million years old — older than those in M36. M38, discovered alongside M36 by Guillaume Le Gentil in 1749, is the most diffuse of the trio: about 100 stars in 25 light-years at 3,900 light-years, magnitude 6.4, appearing cross-shaped or pi-shaped in a telescope. Its brightest member is a yellow G-type giant at magnitude 7.9, and it travels with a companion cluster, NGC 1907, half a degree to the south-southwest.
08 Runaway stars and the Flaming Star Nebula Deeper
AE Aurigae is a hot, blue O9.5-type main-sequence star that does not belong where it is found. Its radial velocity — 58 kilometres per second — differs sharply from the 21 kilometres per second radial velocity of the surrounding Flaming Star Nebula (IC 405), a 9-light-year-wide cloud of glowing gas it currently illuminates. This mismatch indicates the star only recently entered the nebula and is plowing through it as an interloper. Astronomers have hypothesised that AE Aurigae is a runaway star ejected from the young stellar cluster in the Orion Nebula approximately 2.7 million years ago, travelling at high speed ever since. Its companions in flight, 53 Arietis and Mu Columbae, are considered fellow runaways from the same cluster. The nebula's informal name comes from long-exposure photographs, where extensive filaments surrounding the star create the illusion that AE Aurigae is on fire. IC 405 lies close to IC 410, which contains the open cluster NGC 1893, a sparse grouping of about 20 to 30 stars embedded in a faint nebula spanning 40 arcminutes — visible to amateurs only through an Oxygen-III filter.
09 The Aurigid meteor outbursts and Comet Kiess
Most meteor showers are predictable year after year, but the Aurigids are famous for dramatic, unpredictable outbursts. Normally the shower peaks on September 1 with a modest rate of 2–5 meteors per hour and entry velocities of 67 kilometres per second. But in 1935, 1986, 1994, and 2007 the Aurigids erupted spectacularly. The parent body is Comet Kiess (C/1911 N1), discovered in 1911 by Carl Clarence Kiess; the link was pieced together by Cuno Hoffmeister and Arthur Teichgraeber after the 1935 outburst, though a 24-year gap between the comet's return initially made scientists sceptical. In 1994, California observers watched slow, grazing meteors coloured blue and green that left trails at least 45 degrees long and lasted up to 2 seconds — a consequence of their extremely shallow atmospheric entry angle. The peak that year lasted less than two hours. In 2007, astronomer Peter Jenniskens predicted the outburst accurately; a team flying aboard NASA aircraft observed a maximum zenithal hourly rate of 100 meteors per hour at 4:15 am California time on September 1. The Aurigids also share the sky with the Zeta Aurigids, a weak December-to-January shower discovered by William Denning in 1886, and the Delta Aurigids, a faint September-to-October shower found by researchers at New Mexico State University.
10 Hot Jupiters and planetary guests in Auriga Deeper
Several solar-type stars in Auriga harbour confirmed planets, and the roster includes some striking extremes. HAT-P-9 b was the first transiting exoplanet confirmed in the constellation, detected by the transit method in 2008. It is a hot Jupiter of 0.67 Jupiter masses with a radius of 1.4 Jupiter radii, scorching its F-type host star every 3.92 days at a distance of just 0.053 AU. Similarly, KELT-2Ab orbits the late F-dwarf KELT-2A in 4.11 days at comparable proximity; at 1.524 Jupiter masses and 1.290 Jupiter radii, it is massive enough that the brightness of its host — the fifth-brightest transiting-exoplanet host overall — allows its mass and radius to be measured with unusual precision. KELT-2A is itself part of a common-proper-motion binary; its companion KELT-2B, an early K-dwarf, orbits about 295 AU away. At the cooler end of the planetary census, HD 49674 b is a much lighter world at just 0.115 Jupiter masses, hugging its star at 0.058 AU every 4.94 days. HD 40979 b, discovered in 2002, carries 3.83 Jupiter masses and takes 263.1 days to complete a more distant orbit at 0.83 AU, placing it in a region broadly comparable to the inner edge of the habitable zone of a Sun-like star.
11 How constellation boundaries were officially fixed
Auriga has been recognised since antiquity, appearing in Ptolemy's catalogue of 48 constellations in the 2nd century, but its modern legal boundaries are surprisingly recent. In 1922 the International Astronomical Union assigned the three-letter abbreviation "Aur," and in 1930 Belgian astronomer Eugène Delporte drew the official boundaries as a polygon of exactly 20 segments. Those boundaries set Auriga's right ascension between 4 hours 37.5 minutes and 7 hours 30.5 minutes, and its declination between 27.9° and 56.2°. The enclosed area comes to 657 square degrees — large enough to rank it among the bigger constellations, though still only half the size of the largest constellation, Hydra. Because of its northerly declination, Auriga can be seen in its entirety only from latitudes as far south as −34°; observers farther south lose part or all of it below the horizon. One long-standing boundary quirk involves the star Elnath, which traditionally belonged to both Taurus and Auriga as Gamma Aurigae, but is now formally assigned to Taurus as Beta Tauri, leaving Auriga's brightest stars otherwise intact. A now-defunct constellation, Telescopium Herschelii, was created by Maximilian Hell partly from Auriga's stars to honour William Herschel's discovery of Uranus; Johann Bode formalised it in 1801, but it did not survive into modern usage.