Within UFO encounter categories
Do UFO Encounters Leave Physical Traces?
Second-kind encounters focus on reports where UFOs are said to leave marks, effects, or other physical signs that invite investigation.
On this page
- Reported effects and trace evidence
- Notable cases and investigations
- Why physical claims remain debated
Page outline Jump by section
Introduction
Second-kind encounters (often called Close Encounters of the Second Kind, or CE2) occupy a distinctive place in UFO reports because they are not limited to seeing an unusual object: witnesses claim that the event produced measurable effects. These alleged effects range from vehicle or electrical failures to marks on the ground, damaged vegetation, unusual soil changes, radiation readings, or physical reactions in people and animals. The category was introduced by astronomer J. Allen Hynek as part of his close encounter system, which described the structure of reports rather than proving what caused them.[Archania]archania.orgJ. Allen HynekArchaniaJ. Allen HynekMay 25, 2026
The appeal of second-kind cases is clear: a physical trace appears to offer something that can be tested rather than only believed or dismissed. A witness account of a strange light is difficult to evaluate after the fact, but a claimed landing mark, chemical change, or instrument failure creates a possible investigation target. At the same time, physical claims have remained controversial because traces can be difficult to preserve, measurements are often made after the event, and ordinary explanations may account for unusual findings.[Center for UFO Studies]cufos.orgCenter for UFO Studies Close Encounters of the Second KindCenter for UFO StudiesClose Encounters of the Second Kind - Center for UFO Studies…
Reported effects and trace evidence
Second-kind reports cover several different types of alleged physical interaction. The most common claims involve effects on the environment or technology rather than recovered objects.
Ground traces and landing marks are among the best-known examples. Witnesses have reported circular depressions, scorched areas, flattened vegetation, altered soil, or impressions that appear to correspond with a hovering or landed object. These cases attracted particular interest because investigators could photograph locations, collect samples and compare affected areas with nearby control samples.[Exopaedia]exopaedia.orgHynek, Joseph AllenExopaedia:: Hynek, Joseph Allen…
Electromagnetic effects form another major group of claims. Some reports describe car engines stopping, radios failing, lights malfunctioning, or other equipment behaving unusually during a close sighting. These accounts are significant within UFO investigations because they suggest an interaction between the reported object and existing technology, although proving a direct connection is difficult when instruments are not independently monitored.[Biography]biography.comJ. Allen HynekJ. Allen Hynek - Project Blue Book, Quotes & FactsJanuary 4, 2019…
Physiological and biological effects are also included in many CE2 classifications. Witnesses have reported sensations of heat, temporary discomfort, numbness, or other bodily reactions after close encounters. Animal behaviour is sometimes included as well, with reports of livestock becoming disturbed or pets reacting during an event. Such observations may provide additional context, but they are difficult to interpret scientifically because stress, environmental conditions and expectation can influence reactions.[Archania]archania.orgJ. Allen HynekArchaniaJ. Allen HynekMay 25, 2026
The key distinction is that a second-kind report does not mean a physical effect has been scientifically confirmed. It means the witness or investigator claims that a physical effect occurred in connection with the sighting. The evidence question begins after the report: what was measured, how was it measured, and what alternative explanations remain?[Archania]archania.orgJ. Allen HynekArchaniaJ. Allen HynekMay 25, 2026
Notable cases and investigations
The Delphos, Kansas landing trace
One of the most frequently discussed second-kind cases occurred near Delphos, Kansas, on 2 November 1971. Sixteen-year-old Ronald Johnson reported seeing a glowing object close to the ground while tending sheep. After the object departed, a ring-shaped area was reportedly found where the soil appeared unusual. The case became notable because investigators collected soil samples and attempted laboratory analysis rather than relying only on witness testimony.[Center for UFO Studies]cufos.orgCenter for UFO Studies Close Encounters of the Second KindCenter for UFO StudiesClose Encounters of the Second Kind - Center for UFO Studies…
Analyses associated with the case reported differences between soil inside the ring and surrounding material, including changes in water absorption, acidity and chemical composition. Researchers interested in the case argued that these characteristics required explanation, while critics have questioned whether the reported changes necessarily demonstrated an extraordinary cause. The importance of Delphos is therefore not that it settled the question of UFO physical evidence, but that it illustrates the central challenge of CE2 research: unusual measurements do not automatically identify their cause.[ICCRA]iccra.orgICCRA KS Delphos, Ottawa County (November 2, 1971Kansas - Delphos, Ottawa County (November 2, 1971)August 10, 2011…
The Socorro landing case
The 1964 Socorro, New Mexico incident is another influential physical-trace report. Police officer Lonnie Zamora reported seeing an oval object near the ground and later described marks at the site where the object was allegedly positioned. The case became part of the historical record of investigations because it involved a trained observer, a reported close-range observation and a location that investigators could examine.[Reddit]reddit.comThe 3 declassified "Unknowns" from Project Blue Book: When physical trace evidence and radar data completely defied the official ex…
The Socorro case remains debated because investigators have differed over whether the reported marks and witness observations indicate an unknown event or can be explained by more conventional causes. Its lasting influence comes from the combination of a specific location, physical claims and official attention rather than from a universally accepted conclusion.[Reddit]reddit.comThe 3 declassified "Unknowns" from Project Blue Book: When physical trace evidence and radar data completely defied the official ex…
Rendlesham Forest and the problem of mixed evidence
The 1980 Rendlesham Forest incident in Suffolk, England, is often discussed alongside second-kind cases because witnesses reported unusual lights, a possible landed object, ground marks and radiation readings. The event involved United States Air Force personnel stationed at RAF Woodbridge and RAF Bentwaters, making it one of the most prominent military-associated UFO cases.[The Guardian]theguardian.comThe most notable encounter involved U.S. Air Force personnel Jim Penniston, John Burroughs, and Charles Halt, who reported strange lights…
Supporters of the case point to multiple witnesses, contemporary reports and the presence of investigators at the site. Critics argue that some features may have ordinary explanations, including misidentified lights and environmental factors, and that later witness accounts have changed over time. Rendlesham demonstrates why physical-trace cases remain complicated: even when documentation exists, the interpretation of the evidence can remain disputed.[The Guardian]theguardian.comThe most notable encounter involved U.S. Air Force personnel Jim Penniston, John Burroughs, and Charles Halt, who reported strange lights…
Why physical claims remain debated
Physical trace claims appear stronger than simple sightings because they offer the possibility of independent examination. However, scientists and investigators face several recurring problems.
The evidence is often discovered after the event. A soil mark, damaged tree or equipment failure may be real, but connecting it to a particular cause requires showing that the claimed object was responsible. A trace can confirm that something happened without proving what produced it.
Many traces have ordinary possibilities. Soil chemistry can change through natural processes, vegetation can be damaged by weather or human activity, and electrical equipment can fail for many reasons. A CE2 investigation must therefore compare unusual findings against normal environmental and mechanical explanations rather than simply asking whether something appears strange.[ICCRA]iccra.orgICCRA KS Delphos, Ottawa County (November 2, 1971Kansas - Delphos, Ottawa County (November 2, 1971)August 10, 2011…
Evidence preservation is a major limitation. Many historical cases were investigated hours, days or years after the reported event. Samples may have been collected without modern documentation standards, locations may have changed, and original measurements may be unavailable. This makes later reassessment difficult.[Center for UFO Studies]cufos.orgCenter for UFO StudiesISSN: 0730-5748…
The broader significance of second-kind encounters is that they represent the point where UFO reports move from questions of observation into questions of evidence. They have influenced both UFO research and science-fiction storytelling because they imagine a form of contact that leaves a mark on the ordinary world: a footprint, a damaged machine, an altered landscape. Yet the same physical focus that makes these cases compelling also creates the highest standard of proof. A convincing second-kind case would need not only an unusual trace, but a well-documented chain connecting that trace to the reported encounter.
Amazon book picks
Further Reading
Books and field guides related to Do UFO Encounters Leave Physical Traces?. Use these as the next step if you want deeper reading beyond the article.
The UFO Experience: A Scientific Inquiry
Cited by the New York Review of Books as "the best brief for visitation," this classic study presents an analysis of UFO reports and conc...
The Report on Unidentified Flying Objects
The Report on Unidentified Flying Objects, written by Captain Edward Ruppelt in 1956, was the first serious, unbiased account written abo...
UFOs: Generals, Pilots, and Government Officials Go on the Re...
NEW YORK TIMES BESTSELLER • Impeccably researched, this riveting journalistic investigation separates fact from fiction, and documents th...
UFOs and the National Security State: Chronology of a Coverup...
"The documentation is spectacularly good, the best ever on the UFO subject. And the conclusion is overwhelmingly powerful." —Whitley Stri...
eBay marketplace picks
Marketplace Samples
Live-tested eBay searches with available results related to this page.
Selected fromUFO poster oneBay.co.uk.
Endnotes
1.
Source: archania.org
Title: J. Allen Hynek
Link:https://archania.org/p/individuals/scientists/astronomers/[j-allen-hynek
Source snippet
J. Allen HynekMay 25, 2026...
Published: May 25, 2026
2.
Source: exopaedia.org
Title: Hynek, Joseph Allen
Link:https://www.exopaedia.org/Hynek%2C%2BJoseph%2BAllen
Source snippet
Exopaedia:: Hynek, Joseph Allen...
3.
Source: biography.com
Title: J. Allen Hynek
Link:https://www.biography.com/scientists/j-allen-hynek
Source snippet
J. Allen Hynek - Project Blue Book, Quotes & FactsJanuary 4, 2019...
Published: January 4, 2019
4.
Source: iccra.org
Title: ICCRA KS Delphos, Ottawa County (November 2, 1971)
Link:https://iccra.org/bystate/Kansas/ICCRA%20-%20KS%20-%20Delphos%2C%20Ottawa%20County%20%28November%202%2C%201971%29.htm
Source snippet
Kansas - Delphos, Ottawa County (November 2, 1971)August 10, 2011...
Published: November 2, 1971
5.
Source: reddit.com
Link:https://www.reddit.com/r/UAP/comments/1rspczs/the_3_declassified_unknowns_from_project_blue/
Source snippet
The 3 declassified "Unknowns" from Project Blue Book: When physical trace evidence and radar data completely defied the official ex...
6.
Source: cufos.org
Title: Center for UFO Studies Close Encounters of the Second Kind
Link:https://cufos.org/types-of-ufos/close-encounters-of-the-second-kind/
Source snippet
Center for UFO StudiesClose Encounters of the Second Kind - Center for UFO Studies...
7.
Source: cufos.org
Link:https://cufos.org/PDFs/JUFOS/1991_NS_vol3_JUFOS.pdf
Source snippet
Center for UFO StudiesISSN: 0730-5748...
8.
Source: Wikipedia
Title: Close encounter
Link:https://en.wikipedia.org/wiki/Close_encounter
9.
Source: theguardian.com
Link:https://www.theguardian.com/world/2026/apr/30/the-rendlesham-forest-mystery-its-the-perfect-storm-of-a-ufo-case
Source snippet
The most notable encounter involved U.S. Air Force personnel Jim Penniston, John Burroughs, and Charles Halt, who reported strange lights...
10.
Source: awakenche.org
Title: Close Encounters of the Second Kind
Link:https://awakenche.org/knowledge-base/close-encounters-of-the-second-kind/
11.
Source: api.parliament.uk
Title: rendlesham forest incident
Link:https://api.parliament.uk/historic-hansard/written-answers/2001/jan/25/rendlesham-forest-incident
12.
Source: ufocasebook.com
Link:https://www.ufocasebook.com/Kansas.html
13.
Source: cufos.org
Title: Project Blue Book
Link:https://cufos.org/resources/project-blue-book/
14.
Source: nhinewsnetwork.com
Title: rendlesham forest
Link:https://nhinewsnetwork.com/records/united-kingdom/rendlesham-forest/
Additional References
15.
Source: youtube.com
Title: The Lonnie Zamora Incident
Link:https://www.youtube.com/watch?v=J5jnjR1EbMI
Source snippet
UFO Evidence No One Can Explain | Close Encounters 110...
16.
Source: youtube.com
Title: The Center For UFO Studies | Mark Rodeghier
Link:https://www.youtube.com/watch?v=I_QwQVDzpwI
Source snippet
Jacques Vallée -- Dimensions: A Casebook of Alien Contact (part two)...
17.
Source: youtube.com
Title: UFO Evidence No One Can Explain | Close Encounters 110
Link:https://www.youtube.com/watch?v=IHWXhL6g9lU
Source snippet
The Center For UFO Studies | Mark Rodeghier...
18.
Source: paranormal-encyclopedia.com
Link:https://www.paranormal-encyclopedia.com/u/ufo/close-encounters/[first-kind
19.
Source: paranormal-encyclopedia.com
Link:https://www.paranormal-encyclopedia.com/u/ufo/close-encounters/second-kind.html
20.
Source: sciencedirect.com
Link:https://www.sciencedirect.com/science/article/pii/S0376042125000247
21.
Source: historicengland.org.uk
Link:https://historicengland.org.uk/research/results/reports/30-2012?page=18&search=%2A&searchResultsPerPage=100&searchType=research+report&sort=publicationDate+desc
22.
Source: ufomagazines.com
Link:https://www.ufomagazines.com/apro-bulletin-apro-bulletin-1971-11-00-november-december/
23.
Source: theprojectbluebookarchive.org
Link:https://theprojectbluebookarchive.org/archive/
24.
Source: nicap.org
Link:https://www.nicap.org/bluebook/unknowns.htm