Within Sky Charts
Why Low Planets Seem to Move
Objects near the horizon can shimmer, change colour or appear to drift, making a fixed planet seem like a moving craft.
On this page
- Atmospheric effects near the horizon
- Depth cues and apparent motion
- Chart checks for low elevation sightings
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Introduction
Many UFO reports involve a bright light seen low above the horizon that appears to hover, drift, wobble, change colour, or even move against the background. In a significant number of cases, the object is not moving at all. Instead, atmospheric haze and turbulence near the horizon distort the light from a bright planet such as Venus or Jupiter, creating the illusion of motion. Astronomers have long noted that Venus, especially when low in the sky, is one of the most commonly misidentified UFOs. NASA’s Night Sky Network specifically highlights low-horizon Venus as a frequent source of UFO reports. [NASA Science]science.nasa.govScience Identifying UFOs and UAPsNASA ScienceIdentifying UFOs and UAPsDecember 2, 2013 — 1 Dec 2013 — Venus is one of the most confused objects in the sky, especially whe…
For investigators using astronomical charts to check UFO reports, understanding horizon haze is essential. A chart may show a planet fixed in the reported direction, but witnesses often describe movement because the atmosphere has altered what they perceive rather than where the planet actually is.
Atmospheric Effects Near the Horizon
The atmosphere is thickest when looking toward the horizon. Light from a planet must travel through a much longer path of air than it does when the same object is high overhead. Along that path, the light encounters layers of air with different temperatures, densities, and moisture levels. These layers bend and distort the incoming light in constantly changing ways. [Wikipedia]WikipediaSource details in endnotes.
Several effects become especially important:
- Scintillation (twinkling): Rapid fluctuations in brightness and apparent position caused by atmospheric turbulence.
- Atmospheric dispersion: The atmosphere acts like a weak prism, separating colours and making a bright object flash red, blue, green, or white.
- Haze scattering: Dust, pollution, mist, and moisture reduce contrast and create blurred edges.
- Variable refraction: Shifting air layers can slightly alter an object’s apparent position from moment to moment. [Wikipedia]WikipediaSource details in endnotes.
These effects are strongest near the horizon because the light path through the atmosphere is longest there. Scientific descriptions of astronomical scintillation note that apparent changes in brightness and position become much more pronounced at low elevations than near the zenith. [Wikipedia]WikipediaSource details in endnotes.
A bright planet viewed through this turbulent layer can therefore appear alive with motion despite remaining fixed in space.
Why a Fixed Planet Can Look Like a Moving Craft
Witnesses often report that a bright light was “hovering but moving around slightly” or “drifting back and forth”. This description closely matches the visual consequences of atmospheric turbulence.
Apparent Motion Without Real Motion
Turbulent air behaves like a shifting collection of weak lenses. As these air cells move, the light from a distant object is bent by slightly different amounts. To an observer, the object may appear to jump, wobble, pulse, or drift over small angular distances. The object itself remains stationary relative to the stars, but the eye interprets the changing image as movement. [Reddit]reddit.comSomething weird was happening with the star in the middleRedditSomething weird was happening with the star in the middle…July 26, 2024 — This phenomenon, known as atmospheric scintillation, c…
This effect is familiar to astronomers. Reports from observers frequently describe stars or planets seeming to move erratically when atmospheric conditions are poor, particularly near the horizon. [Reddit]reddit.comdisappearing light near venusr/AstronomyThe ISS moves very fast high in the sky and it moves slowly on the horizon…. July 9 2022 Boulder, CO - UFO Sighting? A Mete…
Colour Changes That Suggest Activity
Many UFO witnesses describe lights that switch colours or flash in unusual patterns. Atmospheric dispersion can make a bright low object alternate rapidly between red, orange, yellow, green, blue, and white. Sirius is particularly famous for this effect, but bright planets can display similar behaviour when viewed through turbulent air. [Cloudy Nights]cloudynights.com547826 antares particular blinking apearanceCloudy NightsAntares' particular blinking apearance24 Aug 2016 — Both stars are often the source of "UFO" reports. There are two phenomen…
To someone unfamiliar with atmospheric optics, changing colours may suggest powered manoeuvres, rotating lights, or intelligent control. In reality, the colour shifts are occurring in the atmosphere between the observer and the object.
The “Dancing Light” Illusion
A planet seen through haze often lacks a sharply defined edge. The blurred image makes it difficult for the visual system to judge its exact position. Small fluctuations in brightness and shape can then create the impression that the object is moving more than it really is.
This is especially convincing when the observer focuses on the object for several minutes. Tiny involuntary eye movements combine with atmospheric distortion, reinforcing the sensation that the light is wandering around the sky.
Depth Cues and Apparent Motion
Atmospheric distortion is only part of the story. Human depth perception also becomes unreliable near the horizon.
When a bright planet is viewed against a dark sky with few nearby landmarks, the brain has little information about its distance. The observer knows the object is above the horizon but cannot easily judge whether it is hundreds of metres away or hundreds of millions of kilometres away.
As a result:
- The light may seem much closer than it really is.
- Small atmospheric shifts can appear to be large movements.
- Passing clouds may create the impression that the object is accelerating or changing direction.
- The observer may interpret ordinary celestial motion as active manoeuvring. [EarthSky]earthsky.orgEarth Sky Is that a UFO?!There's probably an explanation15 Dec 2020 — An experimental rocket test over Norway in 2009, which triggered many UFO reports. Read more…
This helps explain why witnesses sometimes describe a bright object as following them, pacing a vehicle, or hovering over a distant hill. The apparent relationship between the light and the landscape is often a product of perspective rather than actual movement.
Chart Checks for Low-Elevation Sightings
When evaluating a UFO report involving a bright light near the horizon, astronomical charts provide a straightforward test.
First, reconstruct the sky for the reported date, time, and location. If a bright planet occupied the reported position, that immediately becomes a candidate explanation. NASA’s guidance for identifying UFO reports specifically notes that Venus, Jupiter, Mercury, Sirius, and other bright objects near the horizon are frequent sources of confusion. [NASA Science]science.nasa.govScience Identifying UFOs and UAPsNASA ScienceIdentifying UFOs and UAPsDecember 2, 2013 — 1 Dec 2013 — Venus is one of the most confused objects in the sky, especially whe…
Several clues strengthen the planetary explanation:
- The object remained in roughly the same compass direction for an extended period.
- The reported motion was slow, erratic, or limited to small shifts.
- Witnesses described flashing colours. [facebook.com]facebook.comYou can see it changing colours in realCan anyone explain what this is please it seemed to be…Can anyone explain what this is please it seemed to be some sort of star but it…
- The sighting occurred through haze, mist, heat shimmer, or light pollution.
- Multiple observers disagreed about how much the object was moving.
Investigators should compare the reported azimuth and elevation with planetarium software or astronomical charts. If Venus or Jupiter appears in the same location and low above the horizon, atmospheric distortion becomes a highly plausible explanation for the perceived motion. [NASA Science]science.nasa.govScience Identifying UFOs and UAPsNASA ScienceIdentifying UFOs and UAPsDecember 2, 2013 — 1 Dec 2013 — Venus is one of the most confused objects in the sky, especially whe…
Why Horizon Reports Require Extra Caution
Not all low-horizon UFO reports are misidentified planets, but horizon observations are among the least reliable visual observations available. The combination of atmospheric turbulence, haze, colour dispersion, poor depth perception, and limited reference points creates ideal conditions for perceptual errors. [Wikipedia]WikipediaSource details in endnotes.
For that reason, a report describing a bright light that hovered, shimmered, changed colour, and appeared to drift slightly near the horizon should always be checked against astronomical charts before more exotic explanations are considered. In many cases, the apparent movement exists not in the sky itself but in the atmosphere through which the observer is looking. NASA Science [Night Sky Network]nightsky.jpl.nasa.govNight Sky Network Identifying UFOs and UAPsBe polite and patient. If the "UFO" is visible and the person inquiring is there in person, you can…Read more…
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Books and field guides related to Why Low Planets Seem to Move. Use these as the next step if you want deeper reading beyond the article.
NightWatch
Helps readers recognise planets and understand how sky position changes with time and horizon angle.
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Useful for learning how objects appear in real observing conditions rather than as abstract chart points.
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Endnotes
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Source: science.nasa.gov
Title: Science Identifying UFOs and UAPs
Link: https://science.nasa.gov/solar-system/skywatching/night-sky-network/identifying-ufos-and-uaps/Source snippet
NASA ScienceIdentifying UFOs and UAPsDecember 2, 2013 — 1 Dec 2013 — Venus is one of the most confused objects in the sky, especially whe...
Published: December 2, 2013
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Source: nightsky.jpl.nasa.gov
Title: Night Sky Network Identifying UFOs and UAPs
Link: https://nightsky.jpl.nasa.gov/news/39/Source snippet
Be polite and patient. If the "UFO" is visible and the person inquiring is there in person, you can...Read more...
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Source: Wikipedia
Link: https://en.wikipedia.org/wiki/Twinkling -
Source: reddit.com
Title: Something weird was happening with the star in the middle
Link: https://www.reddit.com/r/Astronomy/comments/1ecfzh6/something_weird_was_happening_with_the_star_in/Source snippet
RedditSomething weird was happening with the star in the middle...July 26, 2024 — This phenomenon, known as atmospheric scintillation, c...
Published: July 26, 2024
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Source: earthsky.org
Title: Earth Sky Is that a UFO?!
Link: https://earthsky.org/space/if-its-not-a-ufo-what-is-it/Source snippet
There's probably an explanation15 Dec 2020 — An experimental rocket test over Norway in 2009, which triggered many UFO reports. Read more...
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Source: reddit.com
Title: disappearing light near venus
Link: https://www.reddit.com/r/Astronomy/comments/x9vgii/disappearing_light_near_venus/Source snippet
r/AstronomyThe ISS moves very fast high in the sky and it moves slowly on the horizon.... July 9 2022 Boulder, CO - UFO Sighting? A Mete...
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Source: reddit.com
Link: https://www.reddit.com/r/aliens/comments/1syqcee/what_is_this/Source snippet
What is this??: r/aliensPentagon UFO Files Release: Pastors Warn Secret Files Detail 'Demonic Entities' · r/aliens - Pentagon UFO Files...
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Source: reddit.com
Link: https://www.reddit.com/r/askastronomy/comments/hcr63v/why_do_some_stars_twinkle_and_others_dont/Source snippet
tting Earth’s atmosphere, but some other stars weren’t...
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Source: reddit.com
Link: https://www.reddit.com/r/AskPhysics/comments/ripgx5/why_do_some_astronomers_say_that_stars_twinkle/Source snippet
han us one question related to physics. What is it?Read more...
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Source: space.com
Title: 18527 venus atmosphere
Link: https://www.space.com/18527-venus-atmosphere.htmlSource snippet
Venus' atmosphere: Composition, clouds and weather10 Jan 2024 — Venus' atmosphere is made mostly of carbon dioxide, according to NASA. Th...
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Source: cloudynights.com
Title: 547826 antares particular blinking apearance
Link: https://www.cloudynights.com/forums/topic/547826-antares-particular-blinking-apearance/Source snippet
Cloudy NightsAntares' particular blinking apearance24 Aug 2016 — Both stars are often the source of "UFO" reports. There are two phenomen...
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Source: cloudynights.com
Title: 40545 twinkling object in the west
Link: https://www.cloudynights.com/forums/topic/40545-twinkling-object-in-the-west/Source snippet
Twinkling Object in the West21 Sept 2005 — After inputting your location and time, the only thing bright enough in the west at the said t...
Additional References
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Source: sky-lens.com
Link: https://sky-lens.com/guide -
Source: facebook.com
Title: old venus new discovery re analysis of 1970s [nasa data]({{ ‘nasa-data/’ | relative_url }}) shows venus clouds hold w
Link: https://www.facebook.com/WIONews/posts/old-venus-new-discovery-re-analysis-of-1970s-nasa-data-shows-venus-clouds-hold-w/1159639369608569/Source snippet
Old Venus, new discovery: Re-analysis of 1970s NASA...Astronomers examined the chemical composition of Venus's thick atmosphere and foun...
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Source: universemagazine.com
Title: known flying objects sky phenomena we often mistake for ufos
Link: https://universemagazine.com/en/known-flying-objects-sky-phenomena-we-often-mistake-for-ufos/?srsltid=AfmBOoqx52o0acitQPLsoRGKbs3K56V8VgeqfMqPP6rMO6I2yKWX9cz7Source snippet
Known Flying Objects: Sky Phenomena We Often Mistake...12 Oct 2024 — In this article, we delve into the subject of UFOs, particularly th...
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Source: pubs.aip.org
Title: Demonstrations of atmospheric scintillation Stars
Link: https://pubs.aip.org/aapt/pte/article/63/2/134/3332305/Demonstrations-of-atmospheric-scintillation-StarsSource snippet
planets1 Feb 2025 — Here we present easy and straightforward demonstrations for twinkling stars and essentially non-twinkling planets tha...
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Source: medium.com
Link: https://medium.com/%40omarvferro/when-the-sky-tricked-us-the-most-famous-ufos-that-turned-out-to-be-nothing-but-nature-showing-5359c8ff815aSource snippet
misidentified as flashing or moving UFOs near the horizon.Read more...
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Source: medium.com
Link: https://medium.com/starts-with-a-bang/ask-ethan-can-science-explain-ufo-sightings-99cae1fba3aSource snippet
he horizon.... effects of atmospheric distortion on...Read more...
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Source: facebook.com
Link: https://www.facebook.com/AstroKirsten/posts/why-do-stars-twinkle-but-planets-dont-heres-whats-going-oneven-though-stars-are-/1343560821104506/Source snippet
e. Planets typically don't twinkle as much as stars because they...
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Source: kqed.org
Title: ufo lgm omg what is that thing in the sky
Link: https://www.kqed.org/quest/35359/ufo-lgm-omg-what-is-that-thing-in-the-skySource snippet
UFO? LGM? OMG! What is That Thing in the Sky?20 Apr 2012 —... explanation is a flying saucer. My process is to look for the... By the w...
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Source: facebook.com
Link: https://www.facebook.com/bbcherefordandworcester/posts/have-you-ever-seen-a-ufo-or-something-you-couldnt-explaina-new-report-by-nasa-di/10012719115467073/Source snippet
d not conclude extra-terrestrial life exists, but also didn't...
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Source: facebook.com
Title: You can see it changing colours in real
Link: https://www.facebook.com/groups/AstronomyNo1/posts/5192188810826159/Source snippet
Can anyone explain what this is please it seemed to be...Can anyone explain what this is please it seemed to be some sort of star but it...
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