677:, the size of the object depends on the viewing distance. Under normal lighting conditions (light source ~ 1000 lumens at height 600–700 mm, viewing angle ~ 35 degrees) the angular size recognized by naked eye will be round 1 arc minute = 1/60 degrees = 0.0003 radians. At a viewing distance of 16" = ~ 400 mm, which is considered a normal reading distance in the US, the smallest object resolution will be ~ 0.116 mm. For inspection purposes laboratories use a viewing distance of 200–250 mm, which gives the smallest size of the object recognizable to the naked eye of ~0.058–0.072 mm (58–72 micrometers). The
317:
696:
39:
344:. Even a few hundred kilometers away from a metropolitan area where the sky can appear to be very dark, it is still the residual light pollution that sets the limit on the visibility of faint objects. For most people, these are likely to be the best observing conditions within their reach. Under such "typical" dark sky conditions, the naked eye can see stars with an
371:
had most probably been seen but could not be recognized as planets because they appear so faint even at maximum brightness; Uranus's magnitude varies from +5.3 to +5.9, and Vesta's from +5.2 to +8.5 (so that it is only visible near its opposition dates). Uranus, when discovered in 1781, was the first
600:
Many other things can be estimated without an instrument. If an arm is stretched the span of the hand corresponds to an angle of 18 to 20°. The distance of a person, just covered up by the outstretched thumbnail, is about 100 meters. The vertical can be estimated to about 2° and, in the northern
391:
and dust reduces this number somewhat. In the center of a city, where the naked-eye limiting magnitude due to extreme amounts of light pollution can be as low as 2, as few as 50 stars are visible. Colors can be seen but this is limited by the fact that the eye uses
509:
may be visible to the Naked eye only if
Neptune is at its maximum brightness (magnitude +7.8). The Sun and the Moon—the remaining noticeable naked-eye objects of the solar system—are sometimes added to make seven "planets". During daylight only the
849:
Wandell, B. (1995). "Foundations of Vision." Sinauer, Sunderland, MA as cited in
Neurobiology of Attention. (2005). Eds. Laurent Itti, Geraint Rees, and John K., Tsotos. Chapter 102, Elder, J.H. et al. Elsevier,
681:
of a measurement ranges from 0.1 to 0.3 mm and depends on the experience of the observer. The latter figure is the usual positional accuracy of faint details in maps and technical plans.
403:
and galaxies is much more strongly affected by light pollution than is that of planets and stars. Under typical dark conditions only a few such objects are visible. These include the
737:
is a significant problem for amateur astronomers but becomes less late at night when many lights are shut off. Air dust can be seen even far away from a city by its "light dome".
387:
human eye would see the about 5,600 stars brighter than +6 while in perfect dark sky conditions about 45,000 stars brighter than +8 might be visible. In practice, the atmospheric
592:, set a new record as the farthest object that can be seen from Earth with the naked eye. It occurred about 7.5 billion years ago, the light taking that long to reach Earth.
467:
in
Hercules are also visible with the naked eye under such conditions. Under really dark sky conditions, however, M33 is easy to see, even in direct vision. Many other
534:
can be spotted with the naked eye as long as one knows the exact position in which to look. Historically, the zenith of naked-eye astronomy was the work of
860:
538:(1546–1601). He built an extensive observatory to make precise measurements of the heavens without any instruments for magnification. In 1610,
719:
shows how the "blue quality" is degraded depending on the amount of air pollution and dust. The twinkling of a star is an indication of the
896:
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are also visible under such conditions. The most distant objects that have been seen by the naked eye are nearby bright galaxies such as
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up to +6. Under perfect dark sky conditions where all light pollution is absent, stars as faint as +8 might be visible.
103:
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75:
779:
122:
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661:
an accuracy of 0.2 second is possible. This represents only 200 meters at the moon's distance of 385,000 km.
1171:
Detection of weak optical signals by the human visual system: Perspectives in
Neuroscience and in Quantum Physics
360:
82:
868:
311:
60:
155:
89:
574:
204:. Sky lore and various tests demonstrate an impressive variety of phenomena visible to the unaided eye.
649:
were calculated by Mayan astronomers, to within 5 to 10 minutes accuracy in the case of Venus and Mars.
220:
from distances of 25 cm (young people) to 50 cm (most people 50 years and older) to infinity.
56:
20:
71:
444:
355:; however, some people have sharper vision than that. There is anecdotal evidence that people had
230:, approximately 0.017° or 0.0003 radians, which corresponds to 0.3 m at a 1 km distance.
497:
with the naked eye: Mercury, Venus, Mars, Jupiter, and Saturn. Under typical dark sky conditions
185:
49:
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904:
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Meteor showers are better observed by naked eye than with binoculars. Such showers include the
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253:(brightness) to ±10% or 1% of intensity – in a range between night and day of 1:10,000,000,000.
939:
925:
Zezong, Xi, "The
Discovery of Jupiter's Satellite Made by Gan De 2000 years Before Galileo",
824:
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700:
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object and only visible at all if it is higher than 50° in the sky. The globular clusters
8:
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is indicated by the fact that the Milky Way is visible. Comparing the zenith with the
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Visual perception allows a person to gain much information about their surroundings:
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measured all the basics of their respective time and calendar systems by naked eye:
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384:
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the length of a year and a month to ±0.1 hour or to better than 1 minute (0.001%)
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341:
329:
26:"Bare eye" redirects here. For the bird genus commonly known as "bare-eyes", see
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501:(magnitude +5.8) can be seen as well with averted vision, as can the asteroid
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1091:"Night sky and its wonders - Naked eye astronomy | Hurtling Rock"
979:
236:(FOV): simultaneous visual perception in an area of about 160° × 175°.
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The Naked-eye
Planets in the Night Sky (and how to identify them)
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523:
506:
502:
368:
201:
1055:
Astrophysics is Easy! An
Introduction for the Amateur Astronomer
861:"Light Pollution and Astronomy: How Dark Are Your Night Skies?"
772:
Sky
Phenomena: A Guide to Naked Eye Observation of the Heavens.
646:
527:
505:
at its brighter oppositions. Under perfect dark sky conditions
498:
364:
340:
The visibility of astronomical objects is strongly affected by
295:
luminosities and colors and their changes by time and direction
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the distances and 3-dimensional position of things and persons
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Interval estimations (for example at a plan on paper) to 3–5%.
658:
555:
519:
494:
189:
180:, the naked eye may be used to observe celestial events and
511:
333:
240:
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and using a protractor can give the observer's geographic
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of 10–20' (3–6 m per 1 km), see the measurements of
320:
A photographic approximation of a naked eye view of the
1057:. Patrick Moore's Practical Astronomy Series. pp.
787:
Auge und Sehen – der lange Weg zu digitalem
Erkennen.
800:
581:
are other popular objects visible to the naked eye.
63:. Unsourced material may be challenged and removed.
992:
351:The angular resolution of the naked eye is about 1
990:
526:. Close to sunset and sunrise, bright stars like
518:are obvious naked eye objects, but in many cases
312:Limiting magnitude § In naked-eye visibility
1182:
657:by the moon can be observed. By using a digital
546:towards the sky. He immediately discovered the
894:
522:can be spotted in daylight and in rarer cases
380:) rather than being spotted by the naked eye.
818:
816:
595:
212:Some basic properties of the human eye are:
16:Human vision, unaided by optical instruments
1048:
822:
932:
684:
669:Observing a nearby small object without a
399:The visibility of diffuse objects such as
383:Theoretically, in a typical dark sky, the
984:
813:
664:
123:Learn how and when to remove this message
890:
888:
886:
694:
315:
703:, demonstrating clear atmosphere above
332:dramatically reduces the visibility of
1183:
1022:
1020:
883:
823:Yanoff, Myron; Duker, Jay S. (2009).
723:of the air. This is of importance in
1167:Voyages (archived 22 February 2004).
324:from a small rural town (top) and a
61:adding citations to reliable sources
32:
1017:
207:
184:visible without equipment, such as
13:
699:The Milky Way is visible over the
493:can be recognized as planets from
14:
1207:
1138:
363:before telescopes were invented.
146:, is the practice of engaging in
895:John E. Bortle (February 2001).
795:, 20p., Vol.2000/8, Vienna 2000.
565:(10–12 August) and the December
292:) and the slope of plane objects
37:
1109:
1083:
1042:
639:the 24 hours of a day, and the
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48:needs additional citations for
972:
954:
942:. SIMBAD Astronomical Database
919:
867:. 18 July 2006. Archived from
853:
843:
829:. MOSBY Elsevier. p. 54.
609:, up to 1 degree of accuracy.
1:
806:
802:Proceedings, Eisenstadt 1999.
764:
7:
1067:10.1007/978-1-84628-736-7_4
897:"The Bortle Dark-Sky Scale"
740:
575:International Space Station
269:Unconscious recognizing of
247:under a perfectly dark sky.
10:
1212:
688:
601:hemisphere, observing the
309:
303:
25:
21:Naked eye (disambiguation)
18:
826:Ophthalmology 3rd Edition
653:In a similar manner star
596:In geodesy and navigation
372:planet discovered using
1191:Observational astronomy
1121:ESO Picture of the Week
685:Environmental pollution
449:Triangulum Galaxy (M33)
396:to view fainter stars.
1157:and its constellations
1028:"Messier 81 naked-eye"
991:S. J. O'Meara (1998).
708:
665:Small objects and maps
584:19 March 2008 A major
558:, among other things.
431:, the Ptolemy Cluster
337:
277:system" and reflexes).
1151:Naked-Eye Stargazing:
929:2 (3) (1982): 664–67.
698:
394:rods instead of cones
319:
310:Further information:
239:Ability to see faint
1161:Naked Eye Navigation
1097:on 21 September 2013
1049:Inglis Mike (2007).
1001:Cambridge University
774:FlorisBooks (208p),
701:Very Large Telescope
441:globular cluster M13
196:, and the brightest
57:improve this article
19:For other uses, see
1145:Naked Eye Observing
995:The Messier Objects
901:Sky & Telescope
865:skyandtelescope.com
705:Paranal Observatory
645:the periods of the
966:astronomy-mall.com
709:
346:apparent magnitude
338:
224:Angular resolution
159:optical instrument
1076:978-1-85233-890-9
1030:. 10 January 1997
1010:978-0-521-55332-2
798:Kahmen H. (Ed.):
782:, Edinburgh 1993.
622:ancient Egyptians
435:near the tail of
326:metropolitan area
306:Naked-eye planets
148:visual perception
133:
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125:
107:
1203:
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1131:
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1127:
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1093:. Archived from
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1039:
1037:
1035:
1024:
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998:
988:
982:
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962:"Aintno Catalog"
958:
952:
951:
949:
947:
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930:
923:
917:
916:
914:
912:
907:on 23 March 2009
903:. Archived from
892:
881:
880:
878:
876:
871:on 31 March 2014
857:
851:
847:
841:
840:
820:
731:" of astronomy.
671:magnifying glass
548:moons of Jupiter
413:Andromeda Galaxy
361:moons of Jupiter
354:
208:Basic properties
156:light-collecting
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927:Chinese Physics
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752:Satellite flare
743:
735:Light pollution
693:
687:
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626:ancient Indians
598:
588:(GRB) known as
586:gamma-ray burst
573:per night, the
540:Galileo Galilei
481:Sculptor Galaxy
469:Messier objects
451:is a difficult
352:
342:light pollution
330:Light pollution
314:
308:
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226:: about 1
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789:Astro Journal
785:Gerstbach G.:
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770:Davidson, N.:
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461:Canes Venatici
453:averted vision
425:Omega Centauri
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288:the vertical (
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194:meteor showers
171:eye protection
138:, also called
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1117:"Mars, 2099?"
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477:Bode's Galaxy
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417:Carina Nebula
414:
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401:star clusters
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359:the Galilean
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150:unaided by a
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74: –
73:
69:
68:Find sources:
62:
58:
52:
51:
46:This article
44:
40:
35:
34:
29:
22:
1147:in Astronomy
1124:. Retrieved
1120:
1111:
1101:12 September
1099:. Retrieved
1095:the original
1085:
1054:
1044:
1032:. Retrieved
994:
986:
974:
965:
956:
944:. Retrieved
934:
926:
921:
909:. Retrieved
905:the original
873:. Retrieved
869:the original
864:
855:
845:
825:
799:
790:
786:
771:
733:
710:
668:
655:occultations
652:
611:
599:
583:
560:
491:Five planets
489:
421:Orion Nebula
398:
385:dark adapted
382:
350:
339:
300:In astronomy
280:
211:
200:, including
186:conjunctions
175:
161:, such as a
143:
139:
135:
134:
119:
110:
100:
93:
86:
79:
67:
55:Please help
50:verification
47:
1034:13 November
940:"Vmag<6"
911:18 November
792:Sternenbote
725:meteorology
614:Babylonians
590:GRB 080319B
569:. Some 100
536:Tycho Brahe
473:Centaurus A
261:Tycho Brahe
144:unaided eye
113:August 2012
72:"Naked eye"
1185:Categories
1051:"Galaxies"
980:Messier 81
946:3 December
807:References
765:Literature
747:Macrograph
721:turbulence
713:atmosphere
691:Visibility
689:See also:
675:microscope
571:satellites
542:pointed a
485:Messier 83
429:47 Tucanae
409:h/χ Persei
389:extinction
374:technology
328:(bottom).
304:See also:
290:plumb line
273:(that is "
257:Symmetries
251:Photometry
188:, passing
167:microscope
152:magnifying
83:newspapers
28:Phlegopsis
1165:Polynesia
757:ISS flare
641:equinoxes
603:Pole Star
579:Milky Way
544:telescope
433:Messier 7
378:telescope
322:night sky
245:magnitude
243:up to +8
228:arcminute
218:autofocus
198:asteroids
178:astronomy
163:telescope
136:Naked eye
875:6 August
741:See also
711:A clean
679:accuracy
607:latitude
577:and the
567:Geminids
563:Perseids
550:and the
530:or even
445:Hercules
439:and the
437:Scorpius
405:Pleiades
271:movement
140:bare eye
1126:25 June
1059:157–189
717:horizon
647:planets
630:Chinese
532:Canopus
524:Jupiter
507:Neptune
202:4 Vesta
182:objects
97:scholar
1196:Vision
1073:
1007:
978:SEDS,
833:
778:
729:seeing
628:, and
618:Mayans
552:phases
528:Sirius
499:Uranus
483:, and
447:. The
419:, the
415:, the
411:, the
365:Uranus
216:Quick
190:comets
99:
92:
85:
78:
70:
673:or a
659:clock
556:Venus
520:Venus
503:Vesta
495:Earth
369:Vesta
334:stars
275:alarm
241:stars
169:, or
104:JSTOR
90:books
1128:2012
1103:2013
1071:ISBN
1036:2022
1005:ISBN
948:2009
913:2009
877:2013
850:Inc.
831:ISBN
776:ISBN
612:The
514:and
512:Moon
465:M 92
463:and
367:and
357:seen
76:news
1155:Sky
1063:doi
554:of
516:Sun
459:in
457:M 3
443:in
376:(a
176:In
165:or
142:or
59:by
1187::
1163:,
1119:.
1069:.
1061:.
1053:.
1019:^
1003:.
964:.
899:.
885:^
863:.
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111:(
101:·
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
