scholarly journals How dim is dim? Precision of the celestial compass in moonlight and sunlight

2011 ◽  
Vol 366 (1565) ◽  
pp. 697-702 ◽  
Author(s):  
M. Dacke ◽  
M. J. Byrne ◽  
E. Baird ◽  
C. H. Scholtz ◽  
E. J. Warrant
Keyword(s):  
Dung Beetle ◽  
The Sun ◽  
The Moon ◽  
Polarization Pattern ◽  
Animal Group ◽  
Straight Line ◽  
Celestial Orientation ◽  
Polarization Compass ◽  
Celestial Compass ◽  
Diurnal Species

Prominent in the sky, but not visible to humans, is a pattern of polarized skylight formed around both the Sun and the Moon. Dung beetles are, at present, the only animal group known to use the much dimmer polarization pattern formed around the Moon as a compass cue for maintaining travel direction. However, the Moon is not visible every night and the intensity of the celestial polarization pattern gradually declines as the Moon wanes. Therefore, for nocturnal orientation on all moonlit nights, the absolute sensitivity of the dung beetle's polarization detector may limit the precision of this behaviour. To test this, we studied the straight-line foraging behaviour of the nocturnal ball-rolling dung beetle Scarabaeus satyrus to establish when the Moon is too dim—and the polarization pattern too weak—to provide a reliable cue for orientation. Our results show that celestial orientation is as accurate during crescent Moon as it is during full Moon. Moreover, this orientation accuracy is equal to that measured for diurnal species that orient under the 100 million times brighter polarization pattern formed around the Sun. This indicates that, in nocturnal species, the sensitivity of the optical polarization compass can be greatly increased without any loss of precision.

scholarly journals The role of the sun in the celestial compass of dung beetles

2014 ◽  
Vol 369 (1636) ◽  
pp. 20130036 ◽  
Author(s):  
M. Dacke ◽  
Basil el Jundi ◽  
Jochen Smolka ◽  
Marcus Byrne ◽  
Emily Baird
Keyword(s):  
Dung Beetle ◽  
Dung Beetles ◽  
Relative Influence ◽  
The Sun ◽  
Azimuthal Position ◽  
Ball Rolling ◽  
Straight Line ◽  
Celestial Compass ◽  
Compass System

Recent research has focused on the different types of compass cues available to ball-rolling beetles for orientation, but little is known about the relative precision of each of these cues and how they interact. In this study, we find that the absolute orientation error of the celestial compass of the day-active dung beetle Scarabaeus lamarcki doubles from 16° at solar elevations below 60° to an error of 29° at solar elevations above 75°. As ball-rolling dung beetles rely solely on celestial compass cues for their orientation, these insects experience a large decrease in orientation precision towards the middle of the day. We also find that in the compass system of dung beetles, the solar cues and the skylight cues are used together and share the control of orientation behaviour. Finally, we demonstrate that the relative influence of the azimuthal position of the sun for straight-line orientation decreases as the sun draws closer to the horizon. In conclusion, ball-rolling dung beetles possess a dynamic celestial compass system in which the orientation precision and the relative influence of the solar compass cues change over the course of the day.

Celestial Orientation of Fowler's Toad b uFo Fowleri

Behaviour ◽  
1966 ◽  
Vol 26 (1-2) ◽  
pp. 105-123 ◽  
Author(s):  
Hobart F. Landreth ◽  
Denzel E. Ferguson
Keyword(s):  
Breeding Site ◽  
Internal Clock ◽  
The Sun ◽  
The Moon ◽  
Long Distance ◽  
Simultaneous Testing ◽  
Celestial Orientation ◽  
Fowler's Toad ◽  
Clock Mechanism ◽  
Made In

AbstractYoung Fowler's toads from on and near the shores of a lake were tested in a circular pen 60 feet in diameter. Under a variety of conditions (e.g. including group tests, individual tests, simultaneous testing of two groups from different shores, long distance displacement, and transit to the test pen both in view of the sky and in lightproof containers), the toads oriented under the sun to a compass direction (Y-axis) corresponding to a line bisecting the home shoreline at right angles. This orientation persisted after 72 hours in darkness, indicating the existence of an internal clock mechanism. Reorientation to a new shore was evident in 24 hours and was virtually complete after 48 hours. Orientation failed or was partially inhibited in small toads tested under dense cloud cover, at noon, and after sunset. Also, the type of orientation exhibited under the sun was evident at night under the moon, but to a lesser extent under starry skies. These mechanisms are useful in foraging and in dispersal from nursery shores. Adults are oriented at night to the breeding site even without benefit of a chorus for reference. Adults oriented to the Y-axis of the breeding site. A recorded chorus distracted migrating adults pursuing a compass course toward a pond. Non-breeding adults compensated for a displacement made in view of the sun. Celestial orientation is considered a basic orientational mechanism which most likely developed early in anuran history.

scholarly journals Matched-filter coding of sky polarization results in an internal sun compass in the brain of the desert locust

2020 ◽  
Vol 117 (41) ◽  
pp. 25810-25817
Author(s):  
Frederick Zittrell ◽  
Keram Pfeiffer ◽  
Uwe Homberg
Keyword(s):  
Spatial Orientation ◽  
Matched Filter ◽  
Polarized Light ◽  
Central Complex ◽  
Insect Brain ◽  
The Sun ◽  
Polarization Pattern ◽  
Sun Compass ◽  
Small Spot ◽  
Polarization Compass

Many animals use celestial cues for spatial orientation. These include the sun and, in insects, the polarization pattern of the sky, which depends on the position of the sun. The central complex in the insect brain plays a key role in spatial orientation. In desert locusts, the angle of polarized light in the zenith above the animal and the direction of a simulated sun are represented in a compass-like fashion in the central complex, but how both compasses fit together for a unified representation of external space remained unclear. To address this question, we analyzed the sensitivity of intracellularly recorded central-complex neurons to the angle of polarized light presented from up to 33 positions in the animal’s dorsal visual field and injected Neurobiotin tracer for cell identification. Neurons were polarization sensitive in large parts of the virtual sky that in some cells extended to the horizon in all directions. Neurons, moreover, were tuned to spatial patterns of polarization angles that matched the sky polarization pattern of particular sun positions. The horizontal components of these calculated solar positions were topographically encoded in the protocerebral bridge of the central complex covering 360° of space. This whole-sky polarization compass does not support the earlier reported polarization compass based on stimulation from a small spot above the animal but coincides well with the previously demonstrated direct sun compass based on unpolarized light stimulation. Therefore, direct sunlight and whole-sky polarization complement each other for robust head direction coding in the locust central complex.

Selecting the Moon's Limb

1952 ◽  
Vol 5 (2) ◽  
pp. 141-146
Author(s):  
Frances W. Wright
Keyword(s):  
Lower Limb ◽  
The Sun ◽  
The Moon ◽  
The Earth ◽  
Straight Line ◽  
Dark Portion

This paper describes two methods of determining whether a sextant observation of the Moon should be of the upper or lower limb. The first method requires the use of a celestial globe or planisphere; the second is mathematical and requires a certain amount of computation, but is exact.The line which separates the dark portion of the Moon's disk from the illuminated portion is known as the terminator, and the straight line joining the ends of the terminator is that used in this problem. This line is always perpendicular to a line from the Moon to the Sun (the horns being always turned away from the Sun), so that its position can be predicted from the geometrical relations of the Earth, Sun and Moon. This enables the limb to observe to be determined.

The New Moon Illusion

2017 ◽  
Author(s):  
Brian Rogers ◽  
Stuart Anstis
Keyword(s):  
Great Circle ◽  
Cognitive Factors ◽  
The Sun ◽  
The Moon ◽  
Moon Illusion ◽  
Parallel Lines ◽  
Straight Line ◽  
New Moon

When the sun is near the horizon and the moon is visible and higher in the sky, there is a compelling illusion that the sun is not in a direction perpendicular to the boundary between the lit and dark sides of the moon. This New Moon illusion has been observed and discussed previously but without a complete explanation. This chapter argues that both perceptual and cognitive factors contribute to the illusion and that it arises from the fact that the straight line joining the sun and the moon describes a great circle over the flattened dome of the sky. The New Moon illusion also raises the question of how we are able to judge the straightness of extended straight and parallel lines.

How Dung Beetles Steer Straight

2021 ◽  
Vol 66 (1) ◽  
pp. 243-256
Author(s):  
Marie Dacke ◽  
Emily Baird ◽  
Basil el Jundi ◽  
Eric J. Warrant ◽  
Marcus Byrne
Keyword(s):  
Milky Way ◽  
Dung Beetles ◽  
The Sun ◽  
The Moon ◽  
Fixed Bearing ◽  
Polarization Pattern ◽  
Straight Path ◽  
Ball Rolling ◽  
Wide Range ◽  
Night Sky

Distant and predictable features in the environment make ideal compass cues to allow movement along a straight path. Ball-rolling dung beetles use a wide range of different signals in the day or night sky to steer themselves along a fixed bearing. These include the sun, the Milky Way, and the polarization pattern generated by the moon. Almost two decades of research into these remarkable creatures have shown that the dung beetle's compass is flexible and readily adapts to the cues available in its current surroundings. In the morning and afternoon, dung beetles use the sun to orient, but at midday, they prefer to use the wind, and at night or in a forest, they rely primarily on polarized skylight to maintain straight paths. We are just starting to understand the neuronal substrate underlying the dung beetle's compass and the mystery of why these beetles start each journey with a dance.

scholarly journals Multimodal cue integration in the dung beetle compass

2019 ◽  
Vol 116 (28) ◽  
pp. 14248-14253 ◽  
Author(s):  
Marie Dacke ◽  
Adrian T. A. Bell ◽  
James J. Foster ◽  
Emily J. Baird ◽  
Martin F. Strube-Bloss ◽  
...  
Keyword(s):  
South African ◽  
Dung Beetle ◽  
The Sun ◽  
Behavioral Experiments ◽  
Compass Orientation ◽  
Directional Information ◽  
Ball Rolling ◽  
Straight Line ◽  
Memory Network ◽  
Line Path

South African ball-rolling dung beetles exhibit a unique orientation behavior to avoid competition for food: after forming a piece of dung into a ball, they efficiently escape with it from the dung pile along a straight-line path. To keep track of their heading, these animals use celestial cues, such as the sun, as an orientation reference. Here we show that wind can also be used as a guiding cue for the ball-rolling beetles. We demonstrate that this mechanosensory compass cue is only used when skylight cues are difficult to read, i.e., when the sun is close to the zenith. This raises the question of how the beetles combine multimodal orientation input to obtain a robust heading estimate. To study this, we performed behavioral experiments in a tightly controlled indoor arena. This revealed that the beetles register directional information provided by the sun and the wind and can use them in a weighted manner. Moreover, the directional information can be transferred between these 2 sensory modalities, suggesting that they are combined in the spatial memory network in the beetle’s brain. This flexible use of compass cue preferences relative to the prevailing visual and mechanosensory scenery provides a simple, yet effective, mechanism for enabling precise compass orientation at any time of the day.

Modelling Lunar Extremes

2018 ◽  
Vol 3 (2) ◽  
pp. 207-216 ◽  
Author(s):  
David Fisher ◽  
Lionel Sims
Keyword(s):  
High Precision ◽  
Celestial Mechanics ◽  
Computer Modelling ◽  
Landscape Context ◽  
The Sun ◽  
The Moon

Claims first made over half a century ago that certain prehistoric monuments utilised high-precision alignments on the horizon risings and settings of the Sun and the Moon have recently resurfaced. While archaeoastronomy early on retreated from these claims, as a way to preserve the discipline in an academic boundary dispute, it did so without a rigorous examination of Thom’s concept of a “lunar standstill”. Gough’s uncritical resurrection of Thom’s usage of the term provides a long-overdue opportunity for the discipline to correct this slippage. Gough (2013), in keeping with Thom (1971), claims that certain standing stones and short stone rows point to distant horizon features which allow high-precision alignments on the risings and settings of the Sun and the Moon dating from about 1700 BC. To assist archaeoastronomy in breaking out of its interpretive rut and from “going round in circles” (Ruggles 2011), this paper evaluates the validity of this claim. Through computer modelling, the celestial mechanics of horizon alignments are here explored in their landscape context with a view to testing the very possibility of high-precision alignments to the lunar extremes. It is found that, due to the motion of the Moon on the horizon, only low-precision alignments are feasible, which would seem to indicate that the properties of lunar standstills could not have included high-precision markers for prehistoric megalith builders.

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