Venus in the sky

Venus is back in the dawn sky. It passed between Earth and the Sun on 24 October 2026, and on 4 November JPL's Horizons ephemeris puts it 17 degrees west of the Sun and 42.9 million km from Earth, a thin crescent with 4 percent of its disk in sunlight, shining at magnitude -4.4. Three things make it so bright: Venus comes nearer to Earth than any other planet, it is almost Earth's size, and its unbroken cloud reflects most of the light that falls on it. Seen from 40 degrees north it rises about 80 minutes before the Sun, and by 25 November, near its brightest, more than three hours before.

Because its orbit lies inside Earth's, Venus can never appear far from the Sun. Its angle from the Sun peaked at 45.9 degrees to the east on 15 August 2026. So the planet is seen only in the west after sunset or in the east before sunrise, never in the middle of the night. NASA notes that the ancients even took the two guises for two objects. Korean keeps a word for one: the Standard Korean Language Dictionary defines gaebap-baragi as Venus seen in the western sky around evening, beside saetbyeol, the everyday name for the planet. Japan's FUJIN balloon team spells out the cost: from the ground an inner planet can be observed only in the short time when the Sun has set and the planet is still up.

Galileo turned his telescope on the evening Venus around October 1610 and watched it change shape. On 1 January 1611 he wrote from Florence to Giuliano de' Medici in Prague to unscramble an anagram sent some weeks before. Rearranged, its letters read 'the mother of loves imitates the shapes of Cynthia', which he glossed as 'Venus imitates the figures of the Moon'. He described a small round disk that grew, became a perfect half circle and was now thinning into horns, its diameter about five times what it had been at first. The letter draws two conclusions: that the planets are dark bodies, and 'that Venus most necessarily turns around the Sun'.

Those phases explain how Venus's brightness behaves. At superior conjunction, beyond the Sun, the disk is fully lit but small: on 6 January 2026 it was 9.75 arcseconds across and magnitude -3.91. As Venus swings toward Earth the lit fraction shrinks while the disk swells, and the product of the two peaks when the planet is a crescent a fifth to a quarter lit, four to five weeks before or after inferior conjunction. The 2026 peaks, -4.80 in the evening sky and -4.89 in the morning, are more than twice as bright as the full disk of January. At inferior conjunction the disk is at its largest, 61 arcseconds, but only 0.6 percent lit and lost in the Sun's glare.

Which day counts as greatest brilliancy depends on the definition. Japan's National Astronomical Observatory lists the evening peak on 19 September 2026 at magnitude -4.8 and the morning one on 30 November at -4.9. NAOJ computes it from the lit fraction of the disk divided by the squares of Venus's distances from the Sun and Earth, and calls it 'a guide to the magnitude maximum' that does not match it exactly. The Korea Astronomy and Space Science Institute (KASI) calls the November event 'greatest shining area', at 23:00 Korean time on 29 November. From Horizons' illuminated fraction and apparent diameter, the lit area peaks at 23:00 UTC on 18 September, already the 19th in Japan, and 14:00 UTC on 29 November. Horizons' own magnitude model reaches a flat maximum of -4.804 from 23 to 25 September and -4.890 from 24 to 26 November; NAOJ notes that the magnitude peak is 'not necessarily the more accurate one'.

Inferior conjunction, when Venus passes between Earth and the Sun, fell on 24 October 2026. KASI defines it as the moment Venus and the Sun share the same apparent ecliptic longitude and gives 13:00 Korean time, 04:00 UTC; Horizons gives 03:44 UTC. The least distance, 40.81 million km, followed at about 02:00 UTC on 25 October. Venus passed about 6.5 degrees south of the Sun, so there was no transit. NASA's transit catalogue explains that transits currently fall within a day of 7 June or 9 December; the last two came in June 2004 and June 2012, and the next is due in December 2117 (see transits of Venus).

Every 583.92 days, NSSDCA's synodic period, Venus returns to the same place relative to Earth and the Sun. Five such cycles last 2,919.6 days, 2.4 days short of eight calendar years and close to thirteen Venus years, so the calendar of its appearances nearly repeats. Horizons places inferior conjunctions on 26 October 2018, 24 October 2026 and 21 October 2034, each about two and a half days earlier than the last. The conjunctions in between are spread around the sky, each roughly 144 degrees of ecliptic longitude short of the one before, and October 2026 brought Venus back to 211 degrees, close to where it stood in 2018. Five points spaced that way, joined in order, trace a five-pointed star (see Venus time).

NAOJ expects Venus to brighten from magnitude -4.2 at the start of November to -4.9 late in the month. It reaches greatest western elongation, 46.95 degrees, on 3 January 2027 and stays a morning object until superior conjunction on 12 August 2027; ESA's Solar Orbiter is due to swing past it at 22:58 UTC on 24 December 2026, about 948 km above the surface (see Venus flybys). Venus's close approaches to Earth, down to 38.2 million km in NSSDCA's figures, are why it is called Earth's nearest neighbour. Averaged over time the answer changes. In a Physics Today commentary of March 2019, Tom Stockman, Gabriel Monroe and Samuel Cordner calculated a mean distance of 1.14 astronomical units from Earth to Venus and 1.04 to Mercury, and showed that Mercury is on average the nearest planet to every other planet.

Venus has no moon. NSSDCA's planetary fact sheet lists none for Venus or for Mercury, and NASA calls Venus one of only two planets without one. It does have company. The asteroid 2002 VE68 was found on 11 November 2002 by the LONEOS survey in Arizona, a discovery NASA credits to Brian Skiff. Seppo Mikkola, Paul Wiegert and colleagues soon showed it to be a quasi-satellite of Venus, and the International Astronomical Union's naming bulletin of 5 February 2024 calls it the first-identified quasi-satellite of a major planet. The name was an accident. Alex Foster, drawing a solar-system poster for children, read the start of the designation as letters and wrote Zoozve. Latif Nasser of the radio show Radiolab traced the slip with NASA's Liz Landau and suggested that Skiff ask for the name to be made official.

Zoozve orbits the Sun. JPL's Small-Body Database gives it a period of 225 days, matching Venus, on a stretched orbit (eccentricity 0.41) that crosses Earth's path. NASA defines quasi-satellites as asteroids that orbit the Sun while staying close to a planet. Horizons puts it 47.3 million km from Venus on 4 November 2026, 4.4 million km farther than Earth. A moon would have to stay within about 1 million km, the reach of Venus's Hill sphere. Carlos and Raúl de la Fuente Marcos calculated in 2012 that it has been in this state for at least 7,000 years and will stay for about 500 more. Its passes of Earth mostly come eight years apart; the latest, on 2 November 2026 at 6.02 million km, left it around magnitude 15.6, far too faint for the eye.

The asteroid belongs to a small, mostly unseen population. In 2017 the de la Fuente Marcos brothers counted four known co-orbitals of Venus, among them the Trojan 2013 ND15 near the L4 point, and proposed 2015 WZ12 as a fifth. By January 2026 Valerio Carruba, Rafael Sfair and Othon Winter counted twenty, in a preprint on the newest, 2025 TV10, which may leave its shared orbit within about 1,200 years. They are faint and awkwardly placed: in a 2014 simulation by the same authors, nearly 70 percent of the modelled objects pass nearest Earth less than 90 degrees from the Sun. None stays for good. A 2022 study led by Yang-Bo Xu found that Venus Trojans cannot survive the age of the Solar System, and that the faint dust ring seen along Venus's orbit is more likely dust caught for a while in the same resonance.

Why a planet so close to Earth's size kept no moon is still open. A preprint posted on 25 August 2026 by Stephen Kane, Franck Selsis, Jeremy Leconte and Sean Raymond models how tides from the Sun and from a moon would reshape a young Venus that had one. If early Venus spun once in about 12 hours or less, a lunar-mass moon could survive to the present. With spin slower than about 15 hours, or a moon more than about twice the Moon's mass, the orbit decays until tides pull the moon apart, within 0.03 to 1.7 billion years in one of their two tidal models. To match today's planet, Venus must both lose its moon and slow to its present 243-day rotation, and the authors find a limited range of starting conditions that does both through tides alone, with no later catastrophe needed.

Astronomers once thought Venus had a moon. A memoir read to the Paris Academy of Sciences in May 1761 by Baudouin de Guémadeuc quotes Cassini's account of a faint body imitating Venus's phase in 1672 and 1686, recalls James Short's sighting of 1740, and reports that an observer named Montaigne at Limoges saw on 3 May 1761, 20 arcminutes from Venus, a small faint crescent a quarter of the planet's diameter. From three sightings in four days Baudouin derived an orbit of 9 days 7 hours. The phantom is remembered as Neith, after an Egyptian goddess. Paul Stroobant, in a study presented to the Royal Academy of Belgium on 10 May 1887, found background stars at the reported places for many sightings, Montaigne's included. For Cassini's two he found no star and suggested, 'for want of anything better', a mistake in the date.

Besides the Sun's glare, Earth's own air stands in the way. Water vapour above a telescope absorbs the same infrared bands that would show water on Venus, and in the stratosphere, the FUJIN team notes, the sky stays dark even by day. On 28 November 1959 the sealed gondola of Strato-Lab High IV rose from the Stratobowl in South Dakota, carrying Commander Malcolm D. Ross and Charles B. Moore with a Schmidt telescope and spectrograph from John Strong's laboratory at Johns Hopkins University. StratoCat's flight record gives a ceiling of 79,000 ft and a landing in Kansas after about 28 hours, near Frankfort in its narrative and near Blaine in its data table; Gregory Kennedy's Strato-Lab history on the same site gives 81,000 ft and a 16-inch telescope. StratoCat's biography of Strong says the flight detected water vapour on Venus and that other experts disputed the claim.

Strong's group then took the crew out. In a letter dated 27 March 1964 in the Astrophysical Journal, M. Bottema, William Plummer and Strong report that the 1959 telescope and spectrometer, rebuilt as an automatic 30 cm daytime instrument, rode a balloon to 26.5 km on 21 February 1964 and scanned the water band at 1.13 micrometres in sunlight reflected by Venus. Checking the air still above them against sunlight scattered off a white cloth, and finding the Doppler shift of Venus's motion in the absorption lines, they concluded that most of the signal came from Venus. How much water that meant hung on the unknown pressure at the cloud tops, so they gave a range of mixing ratios spanning a factor of about thirty.

Aircraft soon overturned that picture. On 14 May and 11 June 1967 Gerard Kuiper's Arizona group flew a spectrometer at around 37,000 ft on NASA's Convair 990 jet and recorded Venus from 1 to 2.5 micrometres. Their report, dated 15 November 1967, finds the Venus atmosphere essentially devoid of water vapour and ice crystals, and the larger amounts derived from balloons and ground observatories spurious. In 1974 J. B. Pollack and colleagues compared aircraft spectra of Venus with candidate materials and found that only a solution of 75 percent or more sulfuric acid matched the strong absorption near 3 micrometres; airborne spectra analysed in 1978 put the concentration at 84 plus or minus 2 percent. In mid-March 1979, three months into the Pioneer Venus Orbiter mission, the Kuiper Airborne Observatory recorded the first spectra of the Venus disk at wavelengths of 37 to 91 micrometres.

Sounding rockets bought minutes above nearly all the air. D. C. Evans reported Venus's ultraviolet reflectivity from a rocket-borne spectrograph in 1966, and an Aerobee recorded its spectrum from 120 to 180 nm (Bottema, Fastie and Moos, 1969). University of Colorado flights in September 1988 and March 1991 showed sulfur dioxide to be the main absorber at 190 to 230 nm; their instrument could point within 18 degrees of the Sun, while, the authors note, instruments in Earth orbit were held to at least 45. On 15 August 1994 the EUVS payload recorded Venus's far-ultraviolet airglow at five times the previous resolution and showed that emissions credited to argon in Venera 11 and 12 data came from something else. VeSpR, the Venus Spectral Rocket, flew from White Sands on 26 November 2013, reached 300 km and watched Venus for 4 minutes 10 seconds to measure the ratio of deuterium to hydrogen in its upper atmosphere.

Telescopes in Earth orbit kept a longer watch. The International Ultraviolet Explorer detected sulfur dioxide in 1979; its observations of January 1987 and April 1988 showed the cloud-top amount had fallen about eightfold since then, from 380 to 50 parts per billion, and the same study made the first identification of sulfur monoxide there (see volcanoes on Venus). On 13 March 1995 the Hopkins Ultraviolet Telescope, flying on Space Shuttle Endeavour's Astro-2 mission, recorded a far-ultraviolet spectrum of Venus in which carbon monoxide Hopfield-Birge bands were detected for the first time. Chandra observed Venus on 10 and 13 January 2001 for the first X-ray view of the planet: solar X-rays make oxygen and carbon atoms 120 to 140 km up fluoresce, so the X-ray crescent is brightest at the rim. In December 2010 and January 2011 Hubble's STIS spectrograph mapped sulfur oxides at 70 to 80 km in coordination with ESA's Venus Express.

JAXA calls Hisaki (SPRINT-A), launched on the first Epsilon rocket on 14 September 2013, 'the world's first space telescope for planetary observation'; it studied in extreme ultraviolet how the solar wind interacts with the air of Venus and Mars until it was switched off on 8 December 2023, ten years into a mission designed for one. A University of Tokyo team led by Gaku Nishiyama used Venus's chance appearances beside Earth in Himawari-8 and Himawari-9 infrared images to follow its cloud-top temperatures from July 2015 to February 2025; from orbit, they note, Earth hides the Sun even when Venus is close to it. Hokkaido University's 1.6 m Pirka telescope at Nayoro reported long-term Venus monitoring and polarimetry in 2018, and a Subaru COMICS team published mid-infrared cloud-top images in 2014. Still unflown in early November 2026 are FUJIN-2, a 1.4 tonne balloon telescope meant to identify the unknown ultraviolet absorber from a JAXA balloon campaign in Australia (in development on its project page, dated May 2023), and LAPYUTA, an ultraviolet space telescope on ISAS's list of future plans.

Korea's Venus project also stays in Earth orbit. The Planetary Atmospheres Group of the Institute for Basic Science (IBS) in Daejeon, led by Yeon Joo Lee, ran a campaign from September to November 2023 in which ten ground instruments, from Bohyeonsan to Calar Alto, Nayoro and Ussuriysk, observed Venus while Akatsuki and BepiColombo watched from space. Its CLOVE project plans CubeSats in low Earth orbit that observe Venus as a single point of light, each for three years and, with successors, for up to 15. The first, CLOVESat-1, is being built by NanoAvionics under a contract whose work kicked off on 10 January 2025; in January 2026 the Seoul Economic Daily reported a launch around June or July 2026 on a Falcon 9. No launch had been reported by 4 November 2026. In India, a Giant Metrewave Radio Telescope team reported in 2017, from archival data of March 2004, what it calls the first interferometric images of Venus below 620 MHz; the brightness temperatures fall well below those at higher frequencies, a trend thermal models have not explained.