# Zodiacal light <!-- SOLSIM:BEGIN g31 — Solar System explorer state (hand-built on wt-core, specs/solar/); do not hand-edit inside --> **Microsim — three.js (Wikitube framework):** *Interplanetary dust in the Solar System explorer* <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/solar/Solar_System.html?obj=dust&embed=1" data-title="Interplanetary dust in the Solar System explorer"></div> *The Solar System explorer locked on this article's state (`?obj=dust`); every object and population of the [[PORTAL_Solar_System|Solar System portal]] has its own state in the same scene.* <!-- SOLSIM:END --> *Try: drag to an edge-on view and see the dust points thicken into a lens around the Sun and the planets' plane, the cloud whose scattered sunlight is the zodiacal light; press o to hide the orbits and compare the broad cloud with the narrow stream of points along Comet Encke's path; set the speed to 1 month/s and watch Earth circle inside the cloud all year.* The **zodiacal light** is a faint, diffuse glow of sunlight scattered by the dust that lies between the planets. From a dark site it rises from the horizon after evening twilight or before morning twilight as a tilted cone or column, brightest near the Sun's direction and following the zodiac along the [[Ecliptic|ecliptic]].[^apod2012][^reach1997] Before sunrise it is traditionally called the false dawn.[^apod2012][^eso-falsedawn] A much fainter continuation, the zodiacal band, can be traced right around the ecliptic, and directly opposite the [[Sun]] a slightly brighter oval patch, the gegenschein or counterglow, marks light scattered straight back toward [[Earth]]. The dust that produces the glow forms the [[Interplanetary_dust_cloud|interplanetary dust cloud]], a thick, lens-shaped cloud centred on the Sun and straddling the plane of the planets. Its grains are mostly 10–300 micrometres across, with masses from about a nanogram to tens of micrograms.[^peucker2001] Observations from Pioneer 10 and the Helios probes in the 1970s tied the zodiacal light firmly to this cloud.[^hanner1976][^leinert1983] Most of the dust is now attributed to [[Comet|comets]], above all nearly dormant Jupiter-family comets; a proposal that [[Mars]] is a major source remains debated.[^nesvorny2010][^jpl-juno2021] The explorer at the top of this page shows the cloud itself, a field of dust points filling the inner [[PORTAL_Solar_System|Solar System]], seen from outside rather than from Earth's night side. ## Viewing The glow is faint, easily confused with the [[Milky_Way|Milky Way]] where the two cross, so it needs a moonless sky far from artificial light, and it is easily lost to moonlight or light pollution.[^reach1997] It is brightest close to the Sun's direction, because small grains scatter light mostly forward, through small angles. That is why it is seen best just after the end of evening twilight or just before the start of morning twilight: the Sun is then below the horizon, but the dust near the line of sight to it is not. Geometry decides the season. The cone lies along the ecliptic, so it stands highest, and clearest of the murky air near the horizon, when the ecliptic meets the horizon steeply. Earth's axis is tilted 23.44° to its orbit.[^nasa-fs] At a latitude of 45° the ecliptic stands about 90° − 45° + 23.4° ≈ 68° above the western horizon at sunset near the March equinox, but only about 90° − 45° − 23.4° ≈ 22° near the September equinox (derived). Northern mid-latitude observers therefore look west on spring evenings and east before dawn in autumn, and the seasons reverse in the southern hemisphere.[^earthsky2021][^forbes2021] The cone is also wider close to the horizon. Dust well above or below the ecliptic scatters too little light to see except at small angles from the Sun, so more of the cloud's thickness shows near the horizon, where the line of sight passes closest to the hidden Sun, than higher up. ## Origin For a long time the dust was attributed to two sources, the tails of active comets and collisions among asteroids in the [[Asteroid_belt|asteroid belt]].[^espy2006] The first fully dynamical model of the cloud, by David Nesvorný and colleagues in 2010, shifted the balance. It found that only dust released on orbits approaching [[Jupiter]] is stirred up enough to explain how thick the cloud is, and it attributed more than 85% of the dust to occasional break-ups of Jupiter-family comets, those with orbital periods under 20 years, many of them nearly dormant.[^nesvorny2010][^jenniskens2006] Such comets release grains 300–10,000 micrometres across into [[Meteor_shower|meteoroid streams]], which break down into smaller zodiacal grains over time.[^nesvorny2010] Dust analysed by the COSIMA instrument on the Rosetta orbiter at comet 67P/Churyumov–Gerasimenko in 2014–2015 resembled interplanetary dust particles, supporting Jupiter-family comets as parent bodies.[^schulz2015] The cloud must be resupplied because its grains do not last. Poynting–Robertson drag rounds off their orbits and spirals them slowly into the Sun, collisions and space weathering grind them smaller, and grains ground below about 10 micrometres are pushed out by radiation pressure.[^leinert1983] Data from the Juno spacecraft, published from 2020, gave a different picture. Debris knocked off its solar panels by dust impacts, imaged by its star cameras, showed dust between Earth's orbit and the 4:1 [[Resonance|resonance]] with Jupiter at 2.06 AU, a distribution that its authors found best matched Mars as a source.[^jpl-juno2021] How the dust would escape Mars's gravity is not explained, and dust detectors on Pioneer 10 and 11, Galileo, Ulysses and Cassini found no sign of a major Martian contribution.[^humes1980][^grun1997][^soja2019] ## Appearance Because the zodiacal light is reflected sunlight, its spectrum matches the Sun's. The cloud responsible is concentrated toward the plane of the planets and extends well beyond Earth's orbit, so from Earth the light is strongest along the ecliptic and fades away from it.[^reach1997] It takes remarkably little material: the grains in any given volume are very sparse, and the glow is bright only because the line of sight passes through a great depth of the cloud. The explorer shows that cloud from outside, as a field of ILLUSTRATIVE sampled points rather than a density model, with the planets on JPL orbital elements; it does not render the glow as seen from Earth's night side.[^jpl-t1] The gegenschein is thought to come from grains lying directly opposite the Sun as seen from Earth. They are seen fully lit, as the [[Moon]] is at full phase, and so appear a little brighter than the dust around them. Nesvorný and Peter Jenniskens noted that comet dust near 150 micrometres in size meets Earth slowly by the standards of [[Meteoroid|meteoroids]], at 14.5 km/s on average and often as slowly as 12 km/s. Grains that slow can survive entry partly molten, which would explain why most micrometeorites recovered from Antarctic ice look carbonaceous and unlike the larger, asteroidal meteorites.[^nesvorny2010] Detailed maps from infrared satellites also show structure within the glow: dust bands produced by collisions within particular asteroid families, and trails along the orbits of several comets.[^reach1997] ## Cultural significance In his *Kosmos*, Alexander von Humboldt wrote that the peoples of Mesoamerica knew the zodiacal light before 1500.[^ley1961] Giovanni Domenico Cassini made a study of it in 1683.[^jenniskens2006][^fechtig2001] Accounts differ on who first explained it as sunlight scattered by particles around the Sun: some credit Cassini, others Nicolas Fatio de Duillier, whom Cassini had encouraged to study the phenomenon and who proposed the explanation in 1684.[^fechtig2001][^dick2013] The explanation has held since, although the particles were only measured directly in the space age. ### Importance to Islam Islamic law ties the start of the dawn prayer, and of the daily fast in Ramadan, to the first light of dawn, so distinguishing dawn from a lookalike matters. Hadith attributed to the prophet Muhammad contrast a "false dawn" (*al-fajr al-kādhib*), a vertical glow that appears in the east while the sky is still dark and then fades, with the "true dawn" (*al-fajr al-ṣādiq*), the light that spreads horizontally along the horizon.[^muslim1094][^sunnahonline] The false dawn matches the zodiacal light before sunrise, and the distinction is used to avoid beginning the fast or the prayer at the wrong time.[^sunnahonline] ### Brian May Brian May, lead guitarist of the band Queen, began doctoral research on the zodiacal dust cloud at Imperial College London in the early 1970s, measuring the Doppler shifts of solar absorption lines in the zodiacal light to obtain the motions of the dust. He left it unfinished for a career in music and completed it in 2007, some 36 years later; the thesis was published as *A Survey of Radial Velocities in the Zodiacal Dust Cloud*.[^may2007] Little work on the topic had been done in the intervening years, which made it possible to finish the original study. ## Other planets Dust also gathers along the orbits of other planets. Earth has a resonant ring of dust near 1 AU, with a trailing clump, found in infrared data in 1994.[^dermott1994] A faint ring follows the orbit of [[Mercury_(planet)|Mercury]], identified in images from the STEREO spacecraft in 2018.[^stenborg2018] [[Venus]] has a denser dust ring along its orbit, which the Parker Solar Probe imaged around its full circumference in 2021; one proposal is that it is supplied by asteroids sharing Venus's orbit that have not yet been found.[^frazier2021][^pokorny2019] From the outer planets the view would be different. Pioneer 10, looking along the ecliptic on its way to Jupiter, found the zodiacal light fading steadily with distance from the Sun and almost gone beyond the asteroid belt, since the cloud thins out and the sunlight falling on it weakens.[^hanner1976] An observer on Jupiter would therefore see much less zodiacal light than one on Earth, while one on Venus or Mercury, deep in the densest part of the cloud, would see more. Other stars have dust clouds too, known as exozodiacal dust; their glow is a serious source of noise for telescopes trying to image Earth-like planets around those stars.[^backman1998] ## See also - [[Interplanetary_dust_cloud]] · [[Meteoroid]] · [[Meteor_shower]] - [[Ecliptic]] · [[Comet]] - Gegenschein · exozodiacal dust · Kordylewski cloud ## References [^apod2012]: NASA Astronomy Picture of the Day (16 January 2012). "Zodiacal light and the false dawn". https://apod.nasa.gov/apod/ap120116.html [^reach1997]: Reach, W. T. (1997). "The structured zodiacal light: IRAS, COBE, and ISO observations". In *Diffuse Infrared Radiation and the IRTS*, ASP Conference Series 124: 33–40. Bibcode 1997ASPC..124...33R. [^eso-falsedawn]: European Southern Observatory (2017). "False dawn" (Picture of the Week potw1707a). http://www.eso.org/public/images/potw1707a/ [^peucker2001]: Peucker-Ehrenbrink, B.; Schmitz, B. (eds.) (2001). *Accretion of Extraterrestrial Matter Throughout Earth's History*. Springer, pp. 66–67. ISBN 978-0-306-46689-2. [^hanner1976]: Hanner, M. S.; Sparrow, J. G.; Weinberg, J. L.; Beeson, D. E. (1976). "Pioneer 10 observations of zodiacal light brightness near the ecliptic: changes with heliocentric distance". In *Interplanetary Dust and Zodiacal Light*, Lecture Notes in Physics 48: 29–35. https://doi.org/10.1007/3-540-07615-8_448 [^leinert1983]: Leinert, C.; Röser, S.; Buitrago, J. (1983). "How to maintain the spatial distribution of interplanetary dust". *Astronomy and Astrophysics* 118: 345–357. https://articles.adsabs.harvard.edu/pdf/1983A%26A...118..345L [^nesvorny2010]: Nesvorný, D.; Jenniskens, P.; Levison, H. F.; Bottke, W. F.; Vokrouhlický, D.; Gounelle, M. (2010). "Cometary origin of the zodiacal cloud and carbonaceous micrometeorites. Implications for hot debris disks". *The Astrophysical Journal* 713: 816–836. https://doi.org/10.1088/0004-637X/713/2/816 [^jpl-juno2021]: Shekhtman, L. (9 March 2021). "Serendipitous Juno detections shatter ideas about origin of zodiacal light". NASA Jet Propulsion Laboratory. https://www.jpl.nasa.gov/news/serendipitous-juno-detections-shatter-ideas-about-origin-of-zodiacal-light [^nasa-fs]: NASA NSSDCA. "Planetary Fact Sheet" (Earth: obliquity to orbit). https://nssdc.gsfc.nasa.gov/planetary/factsheet/ (fetched 2026-09-18). [^earthsky2021]: EarthSky (6 September 2021). "Zodiacal light: all you need to know". http://earthsky.org/astronomy-essentials/everything-you-need-to-know-zodiacal-light-or-false-dawn [^forbes2021]: Coffey, R. (1 March 2021). "In early March, look to the west for the zodiacal light!". *Forbes*. https://www.forbes.com/sites/rebeccacoffey/2021/03/01/in-early-march-look-to-the-west-for-the-zodiacal-light/ [^espy2006]: Espy, A. J.; Dermott, S. F.; Kehoe, T. J. (2006). "Towards a global model of the zodiacal cloud". *Bulletin of the American Astronomical Society* 38: 557. Bibcode 2006DPS....38.4101E. [^jenniskens2006]: Jenniskens, P. (2006). *Meteor Showers and Their Parent Comets*. Cambridge University Press. ISBN 978-0-521-85349-1. [^schulz2015]: Schulz, R.; Hilchenbach, M.; Langevin, Y.; Kissel, J.; et al. (2015). "Comet 67P/Churyumov–Gerasimenko sheds dust coat accumulated over the past four years". *Nature* 518: 216–218. https://doi.org/10.1038/nature14159 [^humes1980]: Humes, D. H. (1980). "Results of Pioneer 10 and 11 meteoroid experiments: interplanetary and near-Saturn". *Journal of Geophysical Research* 85: 5841–5852. https://doi.org/10.1029/JA085iA11p05841 [^grun1997]: Grün, E.; Staubach, P.; Baguhl, M.; Hamilton, D. P.; Zook, H. A.; et al. (1997). "South–north and radial traverses through the interplanetary dust cloud". *Icarus* 129: 270–288. https://doi.org/10.1006/icar.1997.5789 [^soja2019]: Soja, R. H.; Grün, E.; Strub, P.; Sommer, M.; Millinger, M.; Vaubaillon, J.; et al. (2019). "IMEM2: a meteoroid environment model for the inner solar system". *Astronomy & Astrophysics* 628: A109. https://doi.org/10.1051/0004-6361/201834892 [^ley1961]: Ley, W. (April 1961). "The puzzle called gegenschein". *Galaxy Science Fiction*, pp. 74–84. https://archive.org/stream/Galaxy_v19n04_1961-04#page/n37/mode/1up [^fechtig2001]: Fechtig, H.; Leinert, C.; Berg, O. E. (2001). "Historical perspectives". In Grün, E.; et al. (eds.), *Interplanetary Dust*. Springer, pp. 1–55. https://doi.org/10.1007/978-3-642-56428-4_1 [^dick2013]: Dick, S. J. (2013). *Discovery and Classification in Astronomy: Controversy and Consensus*. Cambridge University Press, p. 350. ISBN 978-1-107-03361-0. [^muslim1094]: Sahih Muslim 1094c, The Book of Fasting. https://sunnah.com/muslim:1094c [^sunnahonline]: "Distinguishing the true dawn from the false dawn". *SunnahOnline*. https://sunnahonline.com/library/fiqh-and-sunnah/732-distinguishing-the-true-dawn-from-the-false-dawn [^jpl-t1]: JPL Solar System Dynamics. "Approximate Positions of the Planets", Table 1. https://ssd.jpl.nasa.gov/planets/approx_pos.html [^backman1998]: Backman, D. E.; Caroff, L. J.; Sandford, S. A.; Wooden, D. H. (eds.) (1998). *Exozodiacal Dust Workshop* (Ames Research Center, 1997). NASA Conference Publication NASA/CP-1998-10155. [^may2007]: May, B. H. (2007). *A Survey of Radial Velocities in the Zodiacal Dust Cloud*. Springer. https://doi.org/10.1007/978-0-387-77706-1 [^dermott1994]: Dermott, S. F.; Jayaraman, S.; Xu, Y. L.; Gustafson, B. Å. S.; Liou, J. C. (1994). "A circumsolar ring of asteroidal dust in resonant lock with the Earth". *Nature* 369: 719–723. https://doi.org/10.1038/369719a0 [^stenborg2018]: Stenborg, G.; Stauffer, J. R.; Howard, R. A. (2018). "Evidence for a circumsolar dust ring near Mercury's orbit". *The Astrophysical Journal* 868: 74. https://doi.org/10.3847/1538-4357/aae6cb [^frazier2021]: Frazier, S. (16 April 2021). "NASA's Parker Solar Probe sees Venus orbital dust ring in first complete view". NASA. http://www.nasa.gov/feature/goddard/2021/nasa-s-parker-solar-probe-sees-venus-orbital-dust-ring-in-first-complete-view [^pokorny2019]: Pokorný, P.; Kuchner, M. (2019). "Co-orbital asteroids as the source of Venus's zodiacal dust ring". *The Astrophysical Journal Letters* 873: L16. https://doi.org/10.3847/2041-8213/ab0827 ## External links - Reach, W. T. (1997). "The structured zodiacal light: IRAS, COBE, and ISO observations". ASP Conference Series 124. https://ui.adsabs.harvard.edu/abs/1997ASPC..124...33R - NASA Astronomy Picture of the Day: zodiacal light and the false dawn. https://apod.nasa.gov/apod/ap120116.html - ESO Picture of the Week: false dawn. http://www.eso.org/public/images/potw1707a/ - NASA JPL: Juno detections and the origin of zodiacal light. https://www.jpl.nasa.gov/news/serendipitous-juno-detections-shatter-ideas-about-origin-of-zodiacal-light ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Zodiacal_light) : [Wikitube](https://en.wikitube.io/wiki/Zodiacal_light) · pinned revision [1347447609](https://en.wikipedia.org/w/index.php?oldid=1347447609) · 2026-09-18 ## Previous hub tags Hubs: `Life_Physics`. Portals: [[PORTAL_Solar_System]]. --- *Solar System portal child articles, wave 1 · 2026-09-18 · drafted · row SOL-082 · explorer state `?obj=dust`.* <!-- hub_tags: Life_Physics · PORTAL_Solar_System -->