Within Venus
Why Low Planets Seem to Change Colour
Low planets can pulse, redden, or flash colours when their light passes through turbulent air, haze, and thin cloud.
On this page
- Scintillation near the horizon
- Haze, cloud, and reddening effects
- When colour change is not enough
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Introduction
Reports of a bright object that flashes red, blue, green, and white near the horizon are among the most common categories of UFO sightings. In many cases, the witness is observing a bright planet—often Venus, but sometimes Jupiter or Mercury—through a particularly difficult section of Earth’s atmosphere. The colour changes can appear dramatic enough to suggest an active craft, a rotating beacon, or an object making controlled movements. Yet the horizon itself is often responsible for much of the spectacle.
The key point is not simply that planets can look colourful. It is that atmospheric turbulence, refraction, haze, and thin cloud layers can combine to create rapid colour shifts and shimmering effects that make a stationary astronomical object appear dynamic and unusual. This mechanism has been recognised for decades in observational astronomy and is especially strong when bright objects are viewed low in the sky. [Wikipedia]WikipediaOpen source on wikipedia.org.
Scintillation Near the Horizon
A planet close to the horizon is seen through a far greater thickness of atmosphere than the same planet viewed high overhead. Light must travel through multiple layers of air that differ in temperature, density, and moisture content. These layers bend the incoming light slightly differently from moment to moment. The result is atmospheric scintillation: rapid variations in brightness, apparent position, and sometimes colour. [Wikipedia]WikipediaAtmospheric refractionAtmospheric refraction
Although planets normally twinkle less than stars because they have a small visible disc rather than appearing as perfect points of light, that advantage weakens near the horizon. The longer atmospheric path increases turbulence effects, allowing even bright planets to shimmer noticeably. Astronomical references note that scintillation becomes much more pronounced as objects approach the horizon because the light crosses more disturbed air before reaching the observer. [Wikipedia]WikipediaIdentification studies of UFOsIdentification studies of UFOs
For UFO witnesses, this matters because the eye often interprets changing brightness as movement or activity. A stationary Venus may appear to pulse, flare, or briefly dim and brighten. Combined with the absence of distance cues at night, these changes can make the object seem alive or responsive when it is actually fixed in celestial position.
Another source of confusion is that turbulence does not merely alter brightness. It can also create tiny shifts in apparent position. While these shifts are usually small, they can produce a visual impression that the object is wobbling, darting, or vibrating against the horizon. [Wikipedia]WikipediaOpen source on wikipedia.org.
Haze, Cloud, and Reddening Effects
Colour-changing reports often involve more than simple twinkling. The atmosphere acts like a weak prism, bending different colours of light by different amounts. Blue wavelengths are refracted more strongly than red wavelengths. Near the horizon this effect becomes much stronger because the viewing angle is so shallow. Astronomers refer to this as atmospheric dispersion. [Astropix]astropix.comAtmospheric Effects ScintillationAstropixAtmospheric EffectsScintillation - Scintillation causes rapid changes in brightness in the celestial object being viewed. This is… [Wikipedia Under steady conditions]WikipediaOpen source on wikipedia.org., atmospheric dispersion can produce subtle colour fringing. Under turbulent conditions, the coloured components can fluctuate independently, causing flashes of red, blue, green, or white. To an observer unfamiliar with the effect, the planet may appear to be actively changing colour. [Astropix]astropix.comAtmospheric Effects ScintillationAstropixAtmospheric EffectsScintillation - Scintillation causes rapid changes in brightness in the celestial object being viewed. This is… [Cloudy Nights]cloudynights.com764513 about the twinkling of starsCloudy NightsAbout the twinkling of stars3 Apr 2021 — Refractive dispersion is due to the fact that air bends blue light more than red, s…
Haze and airborne particles add another layer of distortion. As light passes through a long atmospheric path, shorter blue wavelengths are scattered more efficiently than red wavelengths. This is why celestial objects generally appear redder near the horizon. High humidity, dust, smoke, or pollution can intensify the effect. [Cloudy Nights]cloudynights.com764513 about the twinkling of starsCloudy NightsAbout the twinkling of stars3 Apr 2021 — Refractive dispersion is due to the fact that air bends blue light more than red, s…
Thin cloud can make the appearance even stranger. Passing layers of semi-transparent cloud may briefly attenuate parts of the planet’s light, causing sudden changes in colour balance or brightness. Witnesses sometimes describe this as a light “switching colours” or “rotating through colours”, when the effect is actually being generated by changing atmospheric transmission between the observer and the planet.
A useful clue is that many colour-changing UFO reports occur during twilight or shortly after sunset, exactly when bright planets tend to be low in the sky and atmospheric effects are strongest. This timing is consistent with atmospheric optics rather than with an object generating its own complex light display. [Wikipedia]WikipediaAtmospheric refractionAtmospheric refraction
Why Witnesses Often Overestimate the Effect
Human perception tends to exaggerate subtle colour fluctuations in isolated bright lights. Against a dark background, the eye and brain continuously attempt to interpret brightness and colour. Small atmospheric changes can therefore feel more dramatic than they physically are.
A bright horizon object may be reported as:
- Cycling through multiple colours.
- Pulsing rhythmically.
- Rotating or spinning.
- Hovering while emitting coloured lights.
- Making short, erratic movements.
These descriptions are not necessarily inaccurate accounts of what the witness perceived. The important distinction is that the perceived behaviour may arise from atmospheric distortion acting on a fixed celestial object rather than from the object itself performing those actions.
Astronomers frequently encounter similar effects when observing bright stars and planets at low altitudes. Observers using telescopes often see coloured fringes, flashes, and image instability that disappear once the object climbs higher above the horizon. [Astroshop]astroshop.euAstroshopColour fringing on low-lying planetsColour fringing on planets is very common, even with expensive telescopes. The reason for th…
When Colour Change Is Not Enough
Colour change by itself is weak evidence for an unidentified craft because ordinary atmospheric processes readily produce it. A bright object low in the sky that remains fixed relative to the stars, follows the expected position of a known planet, and exhibits colour flashing or shimmering is consistent with atmospheric scintillation and dispersion. [Wikipedia]WikipediaIdentification studies of UFOsIdentification studies of UFOs
More useful questions are:
- Did the object show sustained motion relative to the background stars?
- Did it change position independently of atmospheric conditions?
- Did multiple observers record the same behaviour from different locations?
- Did the reported movement exceed what could be explained by visual illusion, turbulence, or perspective?
In many UFO investigations, the strongest clue is not the colour itself but the combination of a bright planetary object, a low horizon position, and reports of flashing colours. That pattern closely matches the known optical effects produced when planetary light passes through turbulent air, haze, and thin cloud near the horizon. [Wikipedia]WikipediaIdentification studies of UFOsIdentification studies of UFOs [Wikipedia]WikipediaIdentification studies of UFOsIdentification studies of UFOs
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Endnotes
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Source: Wikipedia
Link: https://en.wikipedia.org/wiki/Twinkling -
Source: Wikipedia
Title: Atmospheric refraction
Link: https://en.wikipedia.org/wiki/Atmospheric_refraction -
Source: astropix.com
Title: Atmospheric Effects Scintillation
Link: https://www.astropix.com/books/GDPI/CHAPTER1/105.HTMSource snippet
AstropixAtmospheric EffectsScintillation - Scintillation causes rapid changes in brightness in the celestial object being viewed. This is...
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Source: astroshop.eu
Link: https://www.astroshop.eu/magazine/practical-tips/peter-s-problem-solvers/colour-fringing-on-low-lying-planets/i%2C1484Source snippet
AstroshopColour fringing on low-lying planetsColour fringing on planets is very common, even with expensive telescopes. The reason for th...
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Source: Wikipedia
Title: Identification studies of UFOs
Link: https://en.wikipedia.org/wiki/Identification_studies_of_UFOs -
Source: hero.epa.gov
Link: https://hero.epa.gov/reference/2583722/Source snippet
of OCS, upper limit to H2S, and latitudinal variations...by VA Krasnopolsky · 2008 · Cited by 58 — Venus was observed at 2.4 and 3.7 mu...
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Source: cloudynights.com
Title: 764513 about the twinkling of stars
Link: https://www.cloudynights.com/forums/topic/764513-about-the-twinkling-of-stars/Source snippet
Cloudy NightsAbout the twinkling of stars3 Apr 2021 — Refractive dispersion is due to the fact that air bends blue light more than red, s...
Additional References
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Source: reddit.com
Link: https://www.reddit.com/r/askastronomy/comments/1fhig5z/a_flickering_object_in_the_northern_hemisphere/Source snippet
A “flickering” object in the northern hemisphere: r/askastronomyBright stars twinkle more, and stars near the horizon twinkle more. They...
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Source: morningstarmissions.space
Link: https://www.morningstarmissions.space/atmosphereanomalies -
Source: aasnova.org
Title: using spacecraft signals to measure sulfur species on venus
Link: https://aasnova.org/2023/05/10/using-spacecraft-signals-to-measure-sulfur-species-on-venus/Source snippet
Using Spacecraft Signals to Measure Sulfur Species on...10 May 2023 — Upcoming missions to Venus will seek trace amounts of sulfur-conta...
Published: May 2023
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Source: primitiveproton.com
Title: Few stars, such as Betelgeuse, [Sirius]({{ ‘sirius/’ | relative_url }}), and Rigel
Link: https://primitiveproton.com/atmospheric-scintillation-why-stars-twinkle-and-planets-dont/Source snippet
Atmospheric Scintillation: Why Stars Twinkle And Planets...It is an astronomical term for changes in stars' brightness or their colors b...
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Source: orbi.uliege.be
Title: ISSI Therm Struct Paper final 12 April 2017
Link: https://orbi.uliege.be/bitstream/2268/213261/1/ISSI-Therm-Struct%20Paper%20-%20final%20-%2012%20April%202017.pdfSource snippet
Thermal Structure of the Venus Atmosphereby SS Limaye · 2017 · Cited by 71 — The atmospheric profiles cover the upper troposphere and mes...
Published: April 2017
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Source: lpi.usra.edu
Title: Venus STDT Report 0409
Link: https://www.lpi.usra.edu/vexag/documents/reports/Venus-STDT-Report-0409.pdfSource snippet
Flagship Mission Study Report 2009Is Xe in Venus' atmosphere mass fractionated from early atmospheric blow-off, like the Earth's or is it...
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Source: arxiv.org
Link: https://arxiv.org/html/2404.07669v2Source snippet
Venus12 Apr 2024 — In this chapter, we will describe how various measurements and models have helped us to characterize Venus, starting w...
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Source: insu.hal.science
Link: https://insu.hal.science/insu-03780953/documentSource snippet
of Venus's dayside disk during the 2020...by YJ Lee · 2022 · Cited by 11 — We performed a unique Venus observation campaign to measure t...
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Source: facebook.com
Link: https://www.facebook.com/groups/physicsisfun109/posts/1025367923475385/ -
Source: ntrs.nasa.gov
Link: https://ntrs.nasa.gov/citations/20030022791Source snippet
The atmospheric pressure makes flight much easier than on planets such as Mars...
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