The Wow signal was a strong narrowband radio signal detected on August 15, 1977

The Wow! awesome represented arsenic "6EQUJ5". The original printout pinch Ehman's handwritten exclamation is preserved by Ohio History Connection.[1]

The Wow! signal was a beardown narrowband power awesome detected connected August 15, 1977, by Ohio State University's Big Ear power scope successful the United States, past utilized to support the search for extraterrestrial intelligence. The awesome appeared to travel from the guidance of the constellation Sagittarius and bore expected hallmarks of extraterrestrial origin.

Astronomer Jerry R. Ehman discovered the anomaly a fewer days later while reviewing the recorded data. On the machine printout, he circled the reference of the signal's intensity, "6EQUJ5", and wrote the remark "Wow!" beside it, starring to the event's wide utilized name.[2]

The full awesome series lasted for the afloat 72-second model during which Big Ear was capable to observe it. Despite galore follow-up searches and hypotheses (including little information of reflections from space debris, interstellar scintillation, and comet hydrogen clouds), the awesome has ne'er recurred, and nary explanation, terrestrial aliases otherwise, has been confirmed. While immoderate researchers person suggested it could correspond an extraterrestrial transmission, its azygous occurrence and deficiency of replication limit the spot of this interpretation. The Wow! awesome has inspired targeted searches, technological chat astir uncommon astrophysical phenomena, and references successful celebrated culture.

In a 1959 paper, Cornell University physicists Philip Morrison and Giuseppe Cocconi had speculated that immoderate extraterrestrial civilization attempting to pass via power signals mightiness do truthful utilizing a wave of 1420 megahertz (21-centimeter spectral line), which is naturally emitted by hydrogen, the astir communal constituent successful the beingness and truthful apt acquainted to each technologically precocious civilizations.[3]

In 1973, aft completing an extended survey of extragalactic power sources, Ohio State University assigned the now-defunct Ohio State University Radio Observatory (nicknamed "Big Ear") to the technological search for extraterrestrial intelligence (SETI), successful the longest-running programme of this benignant successful history.[4] The power scope was located adjacent the Perkins Observatory connected the field of Ohio Wesleyan University successful Delaware, Ohio.[5]

By 1977, Ehman was moving astatine the SETI task arsenic a volunteer; his occupation progressive analyzing by manus ample amounts of information processed by an IBM 1130 machine and recorded connected line printer paper. While perusing information collected connected August 15 astatine 22:16 EST (23:16 EDT section time, 03:16 UTC), he spotted a bid of values of awesome strength and wave that near him and his colleagues astonished.[3] The arena was later documented successful method item by the observatory's director.[6]

Copy of the original machine printout, pinch the awesome successful the bottommost left

Plot of awesome strength versus time

The drawstring 6EQUJ5, commonly misinterpreted arsenic a connection encoded successful the power signal, represents successful truth the signal's intensity variety complete time, expressed successful the peculiar measuring strategy adopted for the experiment. The awesome itself appeared to beryllium an unmodulated continuous wave, though immoderate modulation pinch a play of little than 10 seconds aliases longer than 72 seconds would not person been detectable.[7][8]

The awesome strength was measured arsenic signal-to-noise ratio, pinch the sound (or baseline) averaged complete the erstwhile fewer minutes. The awesome was sampled for 10 seconds and past processed by the computer, which took 2 seconds. The consequence for each wave transmission was printed arsenic a azygous alphanumeric character, representing the 10-second mean strength minus the baseline, expressed arsenic a dimensionless aggregate of the signal's standard deviation.[9]

In this peculiar strength scale, a space character denotes an strength betwixt 0 and 1; that is, betwixt baseline and 1 modular deviation supra it. The numbers 1 to 9 denoted the correspondingly numbered intensities (from 1 to 9); intensities of 10 and supra were indicated by a letter: "A" corresponded to intensities betwixt 10 and 11, "B" to 11 to 12, and truthful on. The Wow! signal's highest measured worth was "U" (an strength betwixt 30 and 31), which is 30 modular deviations supra inheritance noise.[2][9]

John Kraus, the head of the observatory, gave a worth of 1420.3556 MHz successful a 1994 summary written for Carl Sagan.[6] However, Ehman successful 1998 gave a worth of 1420.4556±0.005 MHz.[10] This is (50±5 kHz) supra the hydrogen line worth (with nary red- aliases blue-shift) of 1420.4058 MHz. If owed to blue-shift, it would correspond to the root moving astir 10 km/s (6.2 mi/s) towards Earth.

A heat map of the machine printout, giving a spectrogram of the beam; the Wow! awesome appears arsenic a agleam spot successful the little left.

An mentation of the quality betwixt Ehman's worth and Kraus's tin beryllium recovered successful Ehman's paper. The first local oscillator successful the telescope's power receiver was specified to a wave worth of 1450.4056 MHz. However, the university's purchasing section made a typographical error successful the bid form, alternatively obtaining an oscillator pinch wave 1450.5056 MHz (i.e., 0.1 MHz higher than desired). The package utilized successful the research was past written to set for this error. When Ehman computed the wave of the Wow! signal, he took this correction into account.[citation needed]

The Wow! awesome had a bandwidth of little than 10 kHz. It is considered narrowband emanation successful the consciousness that its fractional bandwidth was comparatively mini (~0.001%). However, the 10 kHz bandwidth is not mini compared to the bandwidth of immoderate astrophysical masers (~1 kHz) aliases to the wave solution of modern narrowband SETI searches (~1 Hz).[11] The Big Ear scope was equipped pinch a receiver tin of measuring 50 10 kHz-wide channels. The output from each transmission was represented successful the machine printout arsenic a file of alphanumeric strength values. The Wow! awesome is fundamentally confined to 1 column.[10]

At the clip of the observation, the Big Ear power scope was only adjustable for altitude (or tallness supra the horizon), and relied connected the rotation of the Earth to scan crossed the sky. Given the velocity of Earth's rotation and the spatial width of the telescope's study window, the Big Ear could observe immoderate fixed constituent for conscionable 72 seconds.[12] A continuous extraterrestrial signal, therefore, would beryllium expected to registry for precisely 72 seconds, and the recorded strength of specified a awesome would show a gradual summation for the first 36 seconds—peaking astatine the halfway of the study window—and past a gradual alteration arsenic the scope moved distant from it. All these characteristics are coming successful the Wow! signal.[13][14]

The 2 regions of abstraction successful the constellation Sagittarius from wherever the Wow! awesome whitethorn person originated. The ambiguity is owed to really the scope was designed. For clarity, the widths (right ascension) of the reddish bands person been exaggerated.

The precise location successful the entity wherever the awesome apparently originated is uncertain owed to the creation of the Big Ear telescope, which featured 2 feed horns, each receiving a beam from somewhat different directions, while pursuing Earth's rotation. The Wow! awesome was detected successful 1 beam but not successful the other, and the information was processed successful specified a measurement that it is intolerable to find which of the 2 horns received the signal.[15] There are, therefore, 2 imaginable right ascension (RA) values for the location of the awesome (expressed beneath successful position of the 2 main reference systems):[16]

B1950 equinox J2000 equinox RA (positive horn) RA (negative horn)

19h22m24.64s ± 5s	19h25m31s ± 10s
19h25m17.01s ± 5s	19h28m22s ± 10s

In contrast, the declination was unambiguously wished to beryllium arsenic follows:

B1950 equinox J2000 equinox Declination

−27°03′ ± 20′	−26°57′ ± 20′

The galactic coordinates for the affirmative horn are l=11.7°, b=−18.9°, and for the antagonistic horn l=11.9°, b=−19.5°, some being truthful astir 19° toward the southeast of the galactic plane, and astir 24° aliases 25° eastbound of the Galactic Center. The region of the entity successful mobility lies northwest of the globular cluster M55, successful the constellation Sagittarius, astir 2.5 degrees southbound of the fifth-magnitude prima group Chi Sagittarii, and astir 3.5 degrees southbound of the level of the ecliptic. The closest easy visible prima is Tau Sagittarii.[17]

Initially, nary adjacent Sun-like stars were known to dishonesty wrong the antenna coordinates, though successful immoderate direction, the antenna shape would encompass astir six distant Sun-like stars arsenic estimated successful 2016.[7] In 2022, a insubstantial published successful the International Journal of Astrobiology identified 3 apt Sun-like stars wrong the antenna-pointed coordinates. The amended characterized star, 2MASS 19281982-2640123, is located 1,800 light-years away, only 132 light-years distant from Maccone's estimation, wherever an intelligent civilization is much apt to exist.[18] The different 2 candidates, 2MASS 19252173-2713537 and 2MASS 19282229-2702492, were insufficiently characterized but still apt to beryllium Sun-like stars. Also, 14 different catalogued stars astatine the antenna coordinates whitethorn still move retired to beryllium akin to the Sun aft much information becomes available.[19][20][21] As a consequence to the discovery, Breakthrough Listen conducted the first targeted hunt for the Wow! Signal successful its first collaboration betwixt the Green Bank Telescope and the Allen Telescope Array of the SETI Institute.[22][23] The observations were performed connected May 21, 2022, lasting 1 hr from Greenbank, 35 minutes from ATA, and 9 minutes and 40 seconds simultaneously.[24] No technosignature candidates were found.[25]

Interstellar scintillation of a weaker continuous signal—similar successful effect to atmospheric twinkling—could beryllium an explanation, but that would not exclude the anticipation of the awesome being artificial successful origin. The importantly much delicate Very Large Array did not observe the signal, and the probability that a awesome beneath the discovery period of the Very Large Array could beryllium detected by the Big Ear owed to interstellar scintillation is low.[26][failed verification] Other hypotheses see a rotating lighthouse-like source, a awesome sweeping successful frequency, aliases a one-time burst.[16]

Ehman said successful 1994: "We should person seen it again erstwhile we looked for it 50 times. Something suggests it was an Earth-sourced awesome that simply sewage reflected disconnected a portion of space debris."[27] He later somewhat recanted his skepticism, aft further investigation showed the unrealistic requirements that a space-borne reflector would request to person to nutrient the observed signal.[10] The signal's wave of 1420 MHz is besides portion of a protected spectrum:[28][29] a wave scope reserved for astronomical investigation successful which terrestrial transmissions are forbidden, though a 2010 study documented respective instances of terrestrial sources either interfering from adjacent wave bands aliases illegally transmitting wrong the spectrum.[30] In a 1997 paper, Ehman resists "drawing immense conclusions from half-vast data"—acknowledging the anticipation that the root whitethorn person been subject aliases different a merchandise of Earth-bound sources.[31] In a 2019 question and reply pinch John Michael Godier, Ehman stated: "I'm convinced that the Wow! awesome surely has the imaginable of being the first awesome from extraterrestrial intelligence."[32]

METI president Douglas Vakoch told Die Welt that immoderate putative SETI awesome detections must beryllium replicated for confirmation, and the deficiency of specified replication for the Wow! awesome intends it has small credibility.[33]

In August 2024, the Planetary Habitability Laboratory published a preprint reporting observations made successful 2020 astatine the Arecibo Observatory successful Puerto Rico, wherever they reason that the Wow! awesome was apt caused by a uncommon astrophysical event, successful which stellar emissions energizing a acold hydrogen cloud caused it to abruptly surge successful brightness.[34][35]

In 2017, Antonio Paris, Assistant Professor of Astronomy and Astrophysics astatine St. Petersburg College, Florida,[36] projected that the hydrogen unreality surrounding 2 comets, 266P/Christensen and 335P/Gibbs, now known to person been successful the aforesaid region of the sky, could person been the root of the Wow! signal.[37][38][39] This presumption was dismissed by astronomers, including members of the original Big Ear investigation team, arsenic the cited comets were not successful the beam astatine the correct time. Furthermore, comets do not emit powerfully astatine the frequencies involved, and location is nary mentation for why a comet would beryllium observed successful 1 beam but not successful the other.[40][41][42]

Several attempts were made by Ehman and different astronomers to retrieve and place the signal. The awesome was expected to hap 3 minutes isolated successful each of the telescope's provender horns, but that did not happen.[14] Ehman unsuccessfully searched for recurrences utilizing Big Ear successful the months aft the detection.[26]

In 1987 and 1989, Robert H. Gray searched for the arena utilizing the META array astatine Oak Ridge Observatory, but did not observe it.[26][43][page needed] In a July 1995 trial of awesome discovery package to beryllium utilized successful its upcoming Project Argus, SETI League executive head H. Paul Shuch made respective drift-scan observations of the Wow! signal's coordinates pinch a 12-meter power scope astatine the National Radio Astronomy Observatory successful Green Bank, West Virginia, besides achieving a null result.

In 1995 and 1996, Gray again searched for the awesome utilizing the Very Large Array, which is importantly much delicate than Big Ear.[26][43][page needed] Gray and Simon Ellingsen later searched for recurrences of the arena successful 1999 utilizing the 26-meter power scope astatine the University of Tasmania's Mount Pleasant Radio Observatory.[44] Six 14-hour observations were made astatine positions successful the vicinity, but thing for illustration the Wow! awesome was detected.[14][43][page needed]

In 2012, connected the 35th day of the Wow! signal, the Arecibo Observatory was said to person beamed a integer watercourse towards Hipparcos 34511, 33277, and 43587.[45] The transmission consisted of astir 10,000 Twitter messages solicited for the intent by the National Geographic Channel, base the hashtag "#ChasingUFOs" (a promotion for 1 of the channel's TV series).[46] The sponsor besides included a bid of video vignettes featuring verbal messages from various celebrities.[47] According to Robert Kerr, the erstwhile head of the Arecibo Observatory who oversaw the Wow! reply, the transmitter overheated soon into the first transmission, and it was only sent successful the guidance of 1 of the targets. It is chartless really galore tweets made it through. None of the targeted stars is wrong the imaginable region from which the Wow! awesome came.[48]

To summation the probability that immoderate extraterrestrial recipients would admit the awesome arsenic an intentional connection from different intelligent life form, Arecibo scientists attached a repeating-sequence header to each message.[46]

The awesome was featured successful the 2024 tv bid 3 Body Problem, successful which the awesome is besides detected successful Inner Mongolia.[49] The awesome was besides referenced successful the 1994 play 2 premiere of The X-Files, "Little Green Men".

The English stone set Muse named their tenth workplace album, released successful June 2026, aft the Wow! signal.[50]

• Arecibo message – Radio connection sent into abstraction successful 1974
• BLC1 (Breakthrough Listen Candidate 1), awesome detected successful 2019
• Fast power burst – Astronomical precocious power transient pulse
• List of interstellar power messages
• Oh-My-God particle
• Quiet and large aliens – Concept successful astrobiology
• Radio awesome from HD 164595 – Star successful the constellation of Hercules
• Radio root SHGb02+14a

• Location connected Google Sky
• Location connected YourSky