Transit of Venus Transit of Venus 1 Transit of Venus A transit of

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					Transit of Venus                                                                                                                     1

    Transit of Venus
    A transit of Venus across the Sun takes place when the planet
    Venus passes directly between the Sun and Earth, becoming
    visible against (and hence obscuring a small portion of) the solar
    disk. During a transit, Venus can be seen from Earth as a small
    black disk moving across the face of the Sun. The duration of such
    transits is usually measured in hours (the transit of 2004 lasted six
    hours). A transit is similar to a solar eclipse by the Moon. While
    the diameter of Venus is almost 3 1/2 times that of the Moon,
    Venus appears smaller, and travels more slowly across the face of
    the Sun, because it is much farther away from Earth.

    Transits of Venus are among the rarest of predictable astronomical
    phenomena.[1] They occur in a pattern that repeats every 243
    years, with pairs of transits eight years apart separated by long                    The 2004 transit of Venus
    gaps of 121.5 years and 105.5 years. The periodicity is a reflection
    of the fact that the orbital periods of Earth and Venus are close to 8:13 and 243:395 commensurabilities.[2][3]
    The next transit of Venus will occur on 5 and 6 June 2012, and will be the last Venus transit this century; the prior
    transit took place on 8 June 2004. The previous pair of transits were in December 1874 and December 1882. After
    2012, the next transits of Venus will be in December 2117 and December 2125.[4][5]
    Venus transits are historically of great scientific importance as they were used to gain the first realistic estimates of
    the size of the Solar System. Observations of the 1639 transit, combined with the principle of parallax, provided an
    estimate of the distance between the Sun and the Earth that was more accurate than any other up to that time. In
    addition, the June 2012 transit will provide scientists with a number of other research opportunities, particularly the
    refinement of techniques to be used in the search for exoplanets.
    A transit of Venus can be safely observed by taking the same precautions used to observe the partial phases of a solar
    eclipse. Staring at the Sun without appropriate eye protection can quickly cause serious and often permanent eye

    Venus, with an orbit inclined by 3.4° relative to the
    Earth's, usually appears to pass under (or over) the Sun
    in the sky at inferior conjunction.[7] A transit occurs
    when Venus reaches conjunction with the Sun at or
    near one of its nodes—the longitude where Venus
    passes through the Earth's orbital plane (the ecliptic).
    Although the inclination between these two orbital
    planes is only 3.4°, Venus can be as far as 9.6° from the
    Sun when viewed from the Earth at inferior
    conjunction.[8] Since the angular diameter of the Sun is
    about half a degree, Venus may appear to pass above or
                                                                    Diagram of transits of Venus and the angle between the orbital
    below the Sun by more than 18 solar diameters during
                                                                                      planes of Venus and Earth
    an ordinary conjunction.[7]
Transit of Venus                                                                                                                  2

    Sequences of transits occur in a pattern that repeats every 243 years, with transits occurring eight years apart
    followed by a gap of 121.5 years, then a gap of eight years and then another long gap of 105.5 years. The pattern
    repeats every 243 years because 243 sidereal orbital periods of the Earth (365.25636 days—slightly longer than the
    tropical year) is 88757.3 days, and 395 sidereal orbital periods of Venus (224.701 days) is 88756.9 days. Thus, after
    this period both Venus and Earth have returned to very nearly the same point in each of their respective orbits. This
    period of time corresponds to 152 synodic periods of Venus.[9]
    The pattern of 105.5, 8, 121.5 and 8 years is not the only pattern that is possible within the 243-year cycle, because
    of the slight mismatch between the times when the Earth and Venus arrive at the point of conjunction. Prior to 1518,
    the pattern of transits was 8, 113.5 and 121.5 years, and the eight inter-transit gaps before the AD 546 transit were
    121.5 years apart. The current pattern will continue until 2846, when it will be replaced by a pattern of 105.5, 129.5
    and 8 years. Thus, the 243-year cycle is relatively stable, but the number of transits and their timing within the cycle
    will vary over time.[9][10]

    Ancient and medieval history
    Ancient Indian, Greek, Egyptian, Babylonian, Mayan and Chinese
    observers knew of Venus and recorded the planet's motions. The early
    Greeks thought that the evening and morning appearances of Venus
    represented two different objects—Hesperus the evening star and
    Phosphorus the morning star.[12] Pythagoras is credited with realizing
    they were the same planet. There is no evidence that any of these
    cultures knew of the transits. Venus was important to ancient American
    civilizations, in particular for the Maya, who called it Noh Ek, "the
    Great Star" or Xux Ek, "the Wasp Star";[13] they embodied Venus in
    the form of the god Kukulkán (also known as or related to Gukumatz
    and Quetzalcoatl in other parts of Mexico). In the Dresden Codex, the
    Maya charted Venus' full cycle, but despite their precise knowledge of
    its course, there is no mention of the transit.[14]

                                                                                 "Venus Tablet of Ammisaduqa", a cuneiform clay
                                                                                     tablet of astrological forecasts from the
                                                                                  Neo-Assyrian period. Library of Ashurbanipal.
                                                                                                  Ref:K.160        .
Transit of Venus                                                                                                                  3

    Modern observations
                                                                                Aside from its rarity, the original scientific
                                                                                interest in observing a transit of Venus was
                                                                                that it could be used to determine the
                                                                                distance from the Earth to the Sun, and from
                                                                                this the size of the Solar System, by
                                                                                employing the parallax method and Kepler's
                                                                                third law. The technique involved making
                                                                                precise observations of the slight difference
                                                                                in the time of either the start or the end of
                                                                                the transit from widely separated points on
                Measuring Venus transit times to determine solar parallax       the Earth's surface. The distance between
                                                                                the points on the Earth was then used as a
    baseline to calculate the distance to Venus and the Sun via triangulation.[15]

    Although by the 17th century astronomers could calculate each planet's relative distance from the Sun in terms of the
    distance of the Earth from the Sun (an astronomical unit), an accurate absolute value of this distance had not been
    In 1627, Johannes Kepler became the first person to predict a transit of Venus, by predicting the 1631 event. His
    methods were not sufficiently accurate to predict that the transit would not be visible in most of Europe, and as a
    consequence, nobody was able to observe the phenomenon.[16]

    1639 – first scientific observation
    The first known observation of a transit of Venus was made by
    Jeremiah Horrocks from his home at Carr House in Much Hoole, near
    Preston in England, on 4 December 1639 (24 November under the
    Julian calendar then in use in England). His friend, William Crabtree,
    also observed this transit from Broughton, near Manchester.[17] Kepler
    had predicted transits in 1631 and 1761 and a near miss in 1639.
    Horrocks corrected Kepler's calculation for the orbit of Venus, realized
    that transits of Venus would occur in pairs 8 years apart, and so
    predicted the transit in 1639.[18] Although he was uncertain of the        Jeremiah Horrocks makes the first observation of
    exact time, he calculated that the transit was to begin at approximately            the transit of Venus in 1639.
    3:00 pm. Horrocks focused the image of the Sun through a simple
    telescope onto a piece of paper, where the image could be safely observed. After observing for most of the day, he
    was lucky to see the transit as clouds obscuring the Sun cleared at about 3:15 pm, just half an hour before sunset.
    Horrocks' observations allowed him to make a well-informed guess as to the size of Venus, as well as to make an
    estimate of the distance between the Earth and the Sun. He estimated that distance to be 59.4 million miles
    (95.6 Gm, 0.639 AU) – about two thirds of the actual distance of 93 million miles (149.6 million km) but a more
    accurate figure than any suggested up to that time. The observations were not published until 1661, well after
    Horrock's death.[18]
Transit of Venus                                                                                                                       4

    1761 and 1769
    In 1663 Scottish mathematician James Gregory had suggested in his Optica Promota that observations of a transit of
    the planet Mercury, at widely spaced points on the surface of the Earth, could be used to calculate the solar parallax
    and hence the astronomical unit. Aware of this, a young Edmund Halley made observations of such a transit in 1676
    from St Helena, but was disappointed to find that there had been only one other observation of the event and was not
    satisfied that the resulting calculation of the solar parallax at 45" was accurate. In 1678 he proposed that more
    accurate calculations could be made using measurements of a transit of Venus, although the next such event was not
    due until 1761. Halley died in 1742, but in 1761 numerous expeditions were made to various parts of the world so
    that precise observations of the transit could be made in order to make the calculations as described by Halley—an
    early example of international scientific collaboration.[19] In an attempt to observe the first transit of the pair,
    scientists and explorers from Britain, Austria and France travelled to destinations around the world, including
    Siberia, Norway, Newfoundland and Madagascar.[20] Most managed to observe at least part of the transit, but
    successful observations were made in particular by Jeremiah Dixon and Charles Mason at the Cape of Good
    On the basis of his observation of the transit of Venus of 1761 from the Petersburg Observatory, Mikhail Lomonosov
    predicted the existence of an atmosphere on Venus. Lomonosov detected the refraction of solar rays while observing
    the transit and inferred that only refraction through an atmosphere could explain the appearance of a light ring
    around the part of Venus that had not yet come into contact with the Sun's disk during the initial phase of transit.[22]
    For the 1769 transit, scientists traveled to Hudson Bay (Canada), San José del Cabo (Baja California, then under
    Spanish control), and Norway. Observations were also made from Tahiti on the first voyage of Captain Cook,[23] at a
    location still known as "Point Venus".[24] The Czech astronomer Christian Mayer was invited by Catherine the Great
    to observe the transit in Saint Petersburg with Anders Johan Lexell, while other members of Russian Academy of
    Sciences went to eight other locations in the Russian Empire.[25] In Philadelphia, the American Philosophical Society
    erected three temporary observatories and appointed a committee, of which David Rittenhouse was the head. The
    results of these observations were printed in the first volume of the Society's Transactions, published in 1771.[26]
    The unfortunate Guillaume Le Gentil spent eight years travelling
    in an attempt to observe either of the transits. His unsuccessful
    journey led to him losing his wife and possessions and being
    declared dead (his efforts became the basis of the play Transit of
    Venus by Maureen Hunter).[20]
    Unfortunately, it was impossible to time the exact moment of the
    start and end of the transit because of the phenomenon known as
    the "black drop effect". This effect was long thought to be due to
    Venus' thick atmosphere, and initially it was held to be the first
    real evidence that Venus had an atmosphere. However, recent
    studies demonstrate that it is an optical effect caused by the           The "black drop effect" visible during the 2004 transit
    smearing of the image of Venus by turbulence in the Earth's
    atmosphere or imperfections in the viewing apparatus.[27][28]

    In 1771, using the combined 1761 and 1769 transit data, the French astronomer Jérôme Lalande calculated the
    astronomical unit to have a value of 153 million kilometers (±1 million km). The calculation was imprecise because
    of the black drop effect, but still a considerable improvement on Horrocks' calculations.[20]
Transit of Venus                                                                                                               5

    1874 and 1882
    Transit observations in 1874 and 1882 allowed this value to be
    refined further. Several expeditions were sent to the Kerguelen
    Archipelago for the 1874 observations. The American astronomer
    Simon Newcomb combined the data from the last four transits, and
    he arrived at a value of about 149.59 million kilometers (±0.31
    million kilometers). Modern techniques, such as the use of radio
    telemetry from space probes, and of radar measurements of the
    distances to planets and asteroids in the Solar System, have
    allowed a reasonably accurate value for the astronomical unit
    (AU) to be calculated to a precision of about ±30 meters. Hence
    the need for parallax calculations has been superseded.[20][28]
                                                                                        The 1882 transit of Venus.

    For details, see Transit of Venus, 2004
    There was a good deal of interest in the 2004 transit as scientists
    attempted to measure the pattern of light dimming as Venus
    blocked out some of the Sun's light, in order to refine techniques
    that they hope to use in searching for extrasolar planets.[28][29]
    Current methods of looking for planets orbiting other stars only
    work for a few cases—planets that are very large (Jupiter-like, not
    Earth-like), whose gravity is strong enough to wobble the star
    sufficiently for us to detect changes in proper motion or Doppler
    shift changes in radial velocity, Jupiter or Neptune sized planets         Transit of Venus from Degania A, Israel, 2004
    very close to their parent star, or through gravitational
    microlensing by planets which pass in front of background stars with the planet-parent star separation comparable to
    the Einstein ring.[30] Measuring light intensity during the course of a transit, as the planet blocks out some of the
    light, is potentially much more sensitive, and might be used to find smaller planets.[28] However, extremely precise
    measurement is needed: for example, the transit of Venus causes the Sun's light to drop by a mere 0.001 magnitude,
    and the dimming produced by small extrasolar planets will be similarly tiny.[31]

    For details, see Transit of Venus, 2012
    The full 2012 transit will be visible from the Pacific Ocean—including Hawai'i, northwestern North America,
    northern Asia, Japan, Korea, New Zealand, central and eastern Australia and the Pacific islands. Most of North
    America and northwestern South America will be able to see the start of the transit before sunset, while southern
    Asia, the Middle East, eastern Africa, western Australia, and most of Europe will be able to observe the end of the
    transit as the Sun rises.[31]
    As with the 2004 transit, the 2012 transit will provide scientists numerous research opportunities, in particular in
    regards to the study of exoplanets. Research of the 2012 Venus transit will include:[32][33][34]
    • Measuring dips in a star's brightness caused by a known planet transiting the Sun will help astronomers find
      exoplanets. Unlike the 2004 Venus transit, the 2012 transit occurs during an active phase of the 11-year activity
      cycle of the Sun, and it is likely to give astronomers practice in picking up a planet's signal around a "spotty"
      variable star.
Transit of Venus                                                                                                                                   6

    • Measurement of the apparent diameter of Venus during the transit, and comparison with its known diameter, will
      give scientists an idea of how to estimate exoplanet sizes.
    • Observation of the atmosphere of Venus simultaneously from Earth-based telescopes and from the Venus Express
      gives scientists a better opportunity to understand the intermediate level of Venus's atmosphere than is possible
      from either viewpoint alone. This will provide new information about the climatology of the planet.
    • Spectrographic study of the well-known atmosphere of Venus will be compared to studies of exoplanets whose
      atmospheres are thus far unknown.
    • The Hubble Space Telescope will use the Moon as a mirror to study the light that bounces off Venus to determine
      the makeup of its atmosphere. This will be a technique that astronomers could also use to study exoplanets.

    Past and future transits
    • For a complete list see NASA's Six Millennium Catalog of Venus
      Transits: 2000 BCE to 4000 CE [35]
    Transits can currently occur only in June or December (see table). The
    time of these events slowly drifts later in the year by about two days
    every 243-year cycle.[9][36] Transits usually occur in pairs, on nearly
    the same date eight years apart. This is because the length of eight
    Earth years is almost the same as 13 years on Venus, so every eight              William Crabtree observing the transit of Venus,
    years the planets are in roughly the same relative positions. This                from The Manchester Murals by Ford Madox
    approximate conjunction usually results in a pair of transits, but it is                            Brown

    not precise enough to produce a triplet, since Venus arrives 22 hours
    earlier each time.[9] The last transit not to be part of a pair was in 1396. The next will be in 3089; in 2854 (the second
    of the 2846/2854 pair), although Venus will just miss the Sun as seen from the Earth's equator, a partial transit will
    be visible from some parts of the southern hemisphere.[37]

                                                                  Past transits of Venus

      Date(s) of            Time (UTC)                                                   Notes                                      Transit path
       transit                                                                                                                     (HM Nautical
                    Start      Mid       End                                                                                         Almanac

    1396 November   15:45     19:27    23:09    Last transit not part of a pair.                                                   [38]

    1518 May        22:46     01:56    05:07                                                                                       [39]
    25–26           May       May      May
                    25        26       26

    1526 May 23     16:12     19:35    21:48    Last transit before invention of telescope                                         [40]

    1631 December   03:51     05:19    06:47    Predicted by Kepler                                                                [41]

    1639 December   14:57     18:25    21:54    First transit observed by Horrocks and Crabtree                                    [42]

    1761 June 6     02:02     05:19    08:37    Lomonosov, Chappe d'Auteroche and others observe from Russia                       [43]

    1769 June 3–4   19:15     22:25    01:35    Cook sent to Tahiti to observe the transit                                         [44]
                    June 3    June 3   June 4

    1874 December   01:49     04:07    06:26    Pietro Tacchini leads expedition to Muddapur, India. A French expedition goes to   [45]
    9                                           New Zealand's Campbell Island
Transit of Venus                                                                                                                                                 7

    1882 December    13:57     17:06     20:15     John Phillip Sousa composes a march, "The Transit of Venus", in honor of the                [46]
    6                                                       [28]

    2004 June 8      05:13     08:20     11:26     Various media networks globally broadcast live video of the Venus transit.                  [47]

                                                                  Future transits of Venus

      Date(s) of                Time (UTC)                                                        Notes                                               Transit
       transit                                                                                                                                          path
                      Start            Mid          End                                                                                               Nautical

    2012 June 5–6 22:09         01:29            04:49       Visible in its entirety from Hawaii, Alaska, Australia,New Zealand, the             [48]
                  June 5        June 6           June 6      Pacific and Eastern Asia, with the beginning of the transit visible from North
                                                             America and the end visible from Europe

    2117            23:58       02:48            05:38       Visible in entirety in eastern China, Japan, Taiwan, Indonesia, and Australia.      [49]
    December        December    December         December    Partly visible on extreme U.S. West Coast, and in India, most of Africa, and
    10–11           10          11               11          the Middle East.

    2125            13:15       16:01            18:48       Visible in entirety in South America and the eastern U.S. Partly visible in         [50]
    December 8                                               Western U.S., Europe, and Africa.

    2247 June 11    08:42       11:33            14:25       Visible in entirety in Africa, Europe, and the Middle East. Partly visible in       [51]
                                                             East Asia and Indonesia, and in North and South America.

    2255 June 9     01:08       04:38            08:08       Visible in entirety in Russia, India, China, and western Australia. Partly          [52]
                                                             visible in Africa, Europe, and the western U.S.

    2360            22:32       01:44            04:56       Visible in entirety in Australia and most of Indonesia. Partly visible in Asia,     [53]
    December        December    December         December    Africa, and the western half of the Americas.
    12–13           12          13               13

    2368            12:29       14:45            17:01       Visible in entirety in South America, western Africa, and the U.S. East Coast. [54]
    December 10                                              Partly visible in Europe, the western U.S., and the Middle East.

    2490 June 12    11:39       14:17            16:55       Visible in entirety through most of the Americas, western Africa, and               [55]
                                                             Europe. Partly visible in eastern Africa, the Middle East, and Asia.

    2498 June 10    03:48       07:25            11:02       Visible in entirety through most of Europe, Asia, the Middle East, and              [56]
                                                             eastern Africa. Partly visible in eastern Americas, Indonesia, and Australia.

    Over longer periods of time, new series of transits will start and old series will end. Unlike the saros series for lunar
    eclipses, it is possible for a transit series to restart after a hiatus. The transit series also vary much more in length
    than the saros series.

    Grazing and simultaneous transits
    Sometimes Venus only grazes the Sun during a transit. In this case it is possible that in some areas of the Earth a full
    transit can be seen while in other regions there is only a partial transit (no second or third contact). The last transit of
    this type was on 6 December 1631, and the next such transit will occur on 13 December 2611.[9] It is also possible
    that a transit of Venus can be seen in some parts of the world as a partial transit, while in others Venus misses the
    Sun. Such a transit last occurred on 19 November 541 BC, and the next transit of this type will occur on 14
    December 2854.[9] These effects occur due to parallax, since the size of the Earth affords different points of view
    with slightly different lines of sight to Venus and the Sun. It can be demonstrated by closing an eye and holding a
    finger in front of a smaller more distant object; when you open the other eye and close the first, the finger will no
    longer be in front of the object.
Transit of Venus                                                                                                                                                 8

    The simultaneous occurrence of a transit of Mercury and a transit of Venus does occur, but extremely infrequently.
    Such an event last occurred on 22 September 373,173 BC and will next occur on 26 July 69,163, and again on 29
    March 224,508.[57][58] The simultaneous occurrence of a solar eclipse and a transit of Venus is currently possible,
    but very rare. The next solar eclipse occurring during a transit of Venus will be on 5 April 15,232.[57] The last time a
    solar eclipse occurred during a transit of Venus was on 1 November 15,607 BC.[59] It could be noticed that the day
    after the Venerean transit of 3 June 1769 there was a total solar eclipse,[60] which was visible in Northern America,
    Europe and Northern Asia.


    Safety precautions
    The safest way to watch a transit is to observe an image of the Sun projected onto a screen through a telescope,
    binoculars, pinhole[61] or reflected pinhole.[62] The event can be viewed without magnification using filters
    specifically designed for this purpose, such as an astronomical solar filter or eclipse viewing glasses coated with a
    vacuum-deposited layer of chromium. However, the disk of Venus is tiny compared to the sun and not much will be
    seen. The once-recommended method of using exposed black-and-white film as a filter is not now considered safe,
    as small imperfections or gaps in the film may permit harmful UV rays to pass through. Observing the Sun directly
    without appropriate protection can damage or destroy retinal cells, causing temporary or permanent

    There are four named "contacts" during a transit—moments when the circumference of Venus touches the
    circumference of the Sun at a single point:
    1.   First contact (external ingress): Venus is entirely outside the disk of the Sun, moving inward
    2.   Second contact (internal ingress): Venus is entirely inside the disk of the Sun, moving further inward
    3.   Third contact (internal egress): Venus is entirely inside the disk of the Sun, moving outward
    4.   Fourth contact (external egress): Venus is entirely outside the disk of the Sun, moving outward.[6]
    A fifth named point is that of greatest transit, when Venus is at the middle of its path across the solar disk and which
    marks the halfway point in the timing of the transit.[6]

    [1] McClure, Bruce (29 May 2012). "Everything you need to know: Venus transit on June 5–6" (http:/ / earthsky. org/ astronomy-essentials/
        last-transit-of-venus-in-21st-century-will-happen-in-june-2012). EarthSky. Earthsky communications inc. . Retrieved 2 June 2012.
    [2] Langford, Peter M. (September 1998). "Transits of Venus" (http:/ / www. astronomy. org. gg/ venustransitsb. htm). La Société Guernesiaise
        Astronomy Section web site (http:/ / www. astronomy. org. gg/ ). Astronomical Society of the Channel Island of Guernsey. . Retrieved
    [3] Shortt, David (2012-05-22). "Some Details About Transits of Venus" (http:/ / www. planetary. org/ blogs/ guest-blogs/
        Some-Details-About-Transits-of-Venus. html). Planetary Society web site (http:/ / www. planetary. org/ ). The Planetary Society. . Retrieved
    [4] John E. Westfall (2003-11). "June 8, 2004:The Transit of Venus" (http:/ / web. archive. org/ web/ 20070808030058/ http:/ / www. lpl.
        arizona. edu/ ~rhill/ alpo/ transitstuff/ transit2004. html). Archived from the original (http:/ / www. lpl. arizona. edu/ ~rhill/ alpo/ transitstuff/
        transit2004. html) on August 8, 2007. . Retrieved 25 September 2006.
    [5] Westfall, John E.. "June 8, 2004:The Transit of Venus" (http:/ / www. alpo-astronomy. org/ transit/ transit2004. html). .
        Retrieved December 8, 2009.
    [6] "Transit of Venus – Safety" (http:/ / www. transit-of-venus. org. uk/ safety. htm). University of Central Lancashire. . Retrieved 21 September
    [7] "Venus compared to Earth" (http:/ / www. esa. int/ SPECIALS/ Venus_Express/ SEM9C3808BE_0. html). European Space Agency. 2000. .
        Retrieved 25 September 2006.
    [8] Juergen Giesen (2003). "Transit Motion Applet" (http:/ / www. venus-transit. de/ TransitMotion/ index. htm). . Retrieved 26 September 2006.
Transit of Venus                                                                                                                                           9

    [9] Fred Espenak (2004-02-11). "Transits of Venus, Six Millennium Catalog: 2000 BCE to 4000 CE" (http:/ / sunearth. gsfc. nasa. gov/ eclipse/
        transit/ catalog/ VenusCatalog. html). NASA. . Retrieved 21 September 2006.
    [10] John Walker. "Transits of Venus from Earth" (http:/ / www. fourmilab. ch/ documents/ canon_transits/ tr_Venus_from_Earth. html. gz).
        Fourmilab Switzerland. . Retrieved 21 September 2006.
    [11] http:/ / www. britishmuseum. org/ research/ search_the_collection_database/ search_object_details. aspx?objectid=314745& partid=1
    [12] Paul Rincon (2005-11-07). "Planet Venus: Earth's 'evil twin'" (http:/ / news. bbc. co. uk/ 1/ hi/ sci/ tech/ 4335628. stm). BBC. . Retrieved 25
        September 2006.
    [13] Morley, Sylvanus G. (1994). The Ancient Maya (5th ed.). Stanford Univ Press. ISBN 978-0-8047-2310-7.
    [14] Bohumil Böhm and Vladimir Böhm. "The Dresden Codex—the Book of Mayan Astronomy" (http:/ / www. volny. cz/ paib/ dresden_codex.
        htm). . Retrieved 25 September 2006.
    [15] Dr. Edmund Halley. A New Method of Determining the Parallax of the Sun, or His Distance from the Earth, Sec. R. S., N0 348 (http:/ /
        sunearth. gsfc. nasa. gov/ eclipse/ transit/ HalleyParallax. html). p. 454. .
    [16] Robert H. van Gent. "Transit of Venus Bibliography" (http:/ / www. staff. science. uu. nl/ ~gent0113/ venus/ venustransitbib. htm). .
        Retrieved 11 September 2009.
    [17] Kollerstrom, Nicholas (2004). "William Crabtree's Venus transit observation" (http:/ / www. dioi. org/ kn/ IAUVenus-Transit. pdf).
        Proceedings IAU Colloquium No. 196, 2004. International Astronomical Union. . Retrieved 10 May 2012.
    [18] Paul Marston (2004). Jeremiah Horrocks—young genius and first Venus transit observer. University of Central Lancashire. pp. 14–37.
    [19] Leverington, David (2003). Babylon to Voyager and beyond: a history of planetary astronomy. Cambridge, UK: Cambridge University
        Press. pp. 140–142. ISBN 0-521-80840-5.
    [20] Prof. Richard Pogge. "Lecture 26:How far to the sun? The Venus Transits of 1761 & 1769" (http:/ / www. astronomy. ohio-state. edu/
        ~pogge/ Ast161/ Unit4/ venussun. html). . Retrieved 25 September 2006.
    [21] "Oxford Dictionary of National Biography: Jeremiah Dixon" (http:/ / www. oxforddnb. com/ view/ article/ 37360). Oxford University Press.
        . Retrieved 22 February 2012.
    [22] Mikhail Ya. Marov (2004). "Mikhail Lomonosov and the discovery of the atmosphere of Venus during the 1761 transit". Proceedings of the
        International Astronomical Union (Cambridge University Press): 209–219.
    [23] Ernest Rhys, ed. (1999). The Voyages of Captain Cook. Wordsworth Editions Ltd. pp. 29–30. ISBN 1-84022-100-3.
    [24] See, for example, Stanley, David (2004). Moon Handbooks South Pacific (http:/ / books. google. com/ ?id=EDGapfBX-CAC& pg=PA175&
        dq=point+ venus+ cook) (8 ed.). Avalon Travel Publishing. p. 175. ISBN 978-1-56691-411-6. .
    [25] Christian Mayer. "An Account of the Transit of Venus: In a Letter to Charles Morton, M. D. Secret. R. S. from Christian Mayer, S. J.
        Translated from the Latin by James Parsons, M. D" (http:/ / visualiseur. bnf. fr/ Visualiseur?O=NUMM-55859& I=203& M=tdm). Royal
        society (GB). Philosophical transactions 54: 163. .
    [26] "American Philosophical Society". Encyclopedia Americana. 1920.
    [27] "Explanation of the Black-Drop Effect at Transits of Mercury and the Forthcoming Transit of Venus" (http:/ / web. archive. org/ web/
        20060710203358/ http:/ / www. aas. org/ publications/ baas/ v35n5/ aas203/ 26. htm). AAS. 2004-01-04. Archived from the original (http:/ /
        www. aas. org/ publications/ baas/ v35n5/ aas203/ 26. htm) on 10 July 2006. . Retrieved 21 September 2006.
    [28] "Transits of Venus—Kiss of the goddess" (http:/ / www. economist. com/ science/ displayStory. cfm?story_id=2705523). The Economist.
        2004-05-27. . Retrieved 25 September 2006.
    [29] Maggie McKee (2004-06-06). "Extrasolar planet hunters eye Venus transit" (http:/ / www. newscientist. com/ article. ns?id=dn5074). New
        Scientist. . Retrieved 27 September 2006.
    [30] A. Gould et al. (2006-06-10). "Microlens OGLE-2005-BLG-169 Implies That Cool Neptune-like Planets Are Common" (http:/ / iopscience.
        iop. org/ 1538-4357/ 644/ 1/ L37/ ). The Astrophysical Journal Letters (The American Astronomical Society) 644 (1): L37–L40.
        arXiv:astro-ph/0603276. Bibcode 2006ApJ...644L..37G. doi:10.1086/505421. .
    [31] Fred Espenak (2002-06-18). "2004 and 2012 Transits of Venus" (http:/ / sunearth. gsfc. nasa. gov/ eclipse/ transit/ venus0412. html). NASA.
        . Retrieved 25 September 2006.
    [32] Wall, Michael (16 May 2012). "Venus Transit On June 5 May Bring New Alien Planet Discoveries" (http:/ / www. huffingtonpost. com/
        2012/ 05/ 16/ venus-transit-june-5-new-alien-planet_n_1522342. html)., Inc.. . Retrieved 21 May 2012.
    [33] "Counting down to the Transit of Venus – our nearest exoplanet test-lab" (http:/ / phys. org/ news/ 2012-03-transit-venus-nearest-exoplanet.
        html). March 5, 2012.
    [34] "The Venus Twilight Experiment: Refraction and scattering phenomena during the transit of Venus on June 5–6, 2012" (https:/ / venustex.
        oca. eu/ foswiki/ ).
    [35] http:/ / eclipse. gsfc. nasa. gov/ transit/ catalog/ VenusCatalog. html
    [36] Although transits occurred in May and November before 1631, this apparent jump in dates was due to the changeover from the Julian
        calendar to the Gregorian calendar on 15 October 1582.
    [37] Steve Bell (2004). "Transits of Venus 1000 AD – 2700 AD" (http:/ / web. archive. org/ web/ 20060907011312/ http:/ / www. nao. rl. ac. uk/
        nao/ transit/ ). HM Nautical Almanac Office. Archived from the original (http:/ / www. nao. rl. ac. uk/ nao/ transit/ ) on September 7, 2006. .
        Retrieved 25 September 2006.
    [38] http:/ / www. hmnao. com/ nao/ transit/ V_1396/
    [39] http:/ / www. hmnao. com/ nao/ transit/ V_1518/
    [40] http:/ / www. hmnao. com/ nao/ transit/ V_1526/
Transit of Venus                                                                                                                                     10

    [41] http:/ / www. hmnao. com/ nao/ transit/ V_1631/
    [42] http:/ / www. hmnao. com/ nao/ transit/ V_1639/
    [43] http:/ / www. hmnao. com/ nao/ transit/ V_1761/
    [44] http:/ / www. hmnao. com/ nao/ transit/ V_1769/
    [45] http:/ / www. hmnao. com/ nao/ transit/ V_1874/
    [46] http:/ / www. hmnao. com/ nao/ transit/ V_1882/
    [47] http:/ / www. hmnao. com/ nao/ transit/ V_2004/
    [48] http:/ / www. hmnao. com/ nao/ transit/ V_2012/
    [49] http:/ / www. hmnao. com/ nao/ transit/ V_2117/
    [50] http:/ / www. hmnao. com/ nao/ transit/ V_2125/
    [51] http:/ / www. hmnao. com/ nao/ transit/ V_2247/
    [52] http:/ / www. hmnao. com/ nao/ transit/ V_2255/
    [53] http:/ / www. hmnao. com/ nao/ transit/ V_2360/
    [54] http:/ / www. hmnao. com/ nao/ transit/ V_2368/
    [55] http:/ / www. hmnao. com/ nao/ transit/ V_2490/
    [56] http:/ / www. hmnao. com/ nao/ transit/ V_2498/
    [57] "Hobby Q&A", Sky&Telescope, August 2004, p. 138.
    [58] Fred Espenak (2005-04-21). "Transits of Mercury, Seven Century Catalog: 1601 CE to 2300 CE" (http:/ / sunearth. gsfc. nasa. gov/ eclipse/
        transit/ catalog/ MercuryCatalog. html). NASA. . Retrieved 27 September 2006.
    [59] Jeliazkov, Jeliazko. "Simultaneous occurrence of solar eclipse and a transit" (http:/ / transit. savage-garden. org/ en/ sedt. html). . Retrieved 2009-08-11.
    [60] de La Lande, M.; Messier, M. (1769). "Observations of the Transit of Venus on 3 June 1769, and the Eclipse of the Sun on the Following
        Day, Made at Paris, and Other Places. Extracted from Letters Addressed from M. De la Lande, of the Royal Academy of Sciences at Paris, and
        F. R. S. to the Astronomer Royal; And from a Letter Addressed from M. Messier to Mr. Magalhaens". Philosophical Transactions
        (1683–1775) 59 (0): 374–377. Bibcode 1769RSPT...59..374D. doi:10.1098/rstl.1769.0050.
    [61] "Solar Eclipse: A How-To Guide for Viewing Eclipses | Exploratorium" (http:/ / www. exploratorium. edu/ eclipse/ how. html). . Retrieved 2012-05-21.
    [62] "Using a mirror as a pinhole to produce an image of the sun" (http:/ / www2. eng. cam. ac. uk/ ~hemh/ transit. htm). Trinity College
        Cambridge. . Retrieved 2012-05-26.
    [63] Fred Espenak. "Eye Safety During Solar Eclipses (Adapted from NASA RP 1383 Total Solar Eclipse of 1998 February 26, April 1996, p.
        17.)" (http:/ / sunearth. gsfc. nasa. gov/ eclipse/ SEhelp/ safety. html). . Retrieved 21 September 2006.
    [64] Michaelides M, Rajendram R, Marshall J, Keightley S. (April 2001). "Eclipse retinopathy". Eye (Lond) 15(Pt 2): 148–51.

    Further reading
    • Chauvin, Michael (2004). Hokuloa: The British 1874 Transit of Venus Expedition to Hawaii (http://www. Honolulu: Bishop Museum Press. ISBN 1-581-78023-0.
    • Maor, Eli (2000). Venus in Transit ( Princeton: Princeton
      University Press. ISBN 0-691-11589-3.
    • Maunder, Michael; Moore, Patrick (2000). Transit: When Planets Cross the Sun (
      dp/1852336218). London: Springer-Verlaf. ISBN 1-85233-621-8.
    • Sellers, David (2001). The Transit of Venus: The Quest to Find the True Distance of the Sun (http://www. Leeds, UK: Magavelda Press. ISBN 0-9541013-0-8.
    • Sheehan, William; Westfall, John (2004). The Transits of Venus (
      Amherst, New York: Prometheus Books. ISBN 1-59102-175-8.
    • Lomb, Nick (2011). Transit of Venus: 1631 to the Present (
      Sydney, Australia: NewSouth Publishing. ISBN 978-1-74223-269-0. OCLC 717231977.
    • Wulf, Andrea (2012). Chasing Venus: The Race to Measure the Heavens (
      0307700178). New York: Knopf. ISBN 978-0-307-70017-9.
    • Anderson, Mark (2012). The Day the World Discovered the Sun: An Extraordinary Story of Scientific Adventure
      and the Race to Track the Transit of Venus ( Boston: Da Capo
      Press. ISBN 978-0-306-82038-0.
Transit of Venus                                                                                                       11

    External links
    • Transit of Venus – article posts from various authors, historians, astronomers (
    • Venus Transits: Measuring the Solar System (
    • Historical observations of the transit of Venus (
    • The transit of Venus across the Sun (
    June 2012 transit
    • Advice from professional Astronomers about observing the transit (
    • NASA – 2012 Transit of Venus Live Webcast and Celebration (
    • Transit of Venus from (
    • 2012 Transit of Venus – International Astronomical Union (
    • Watch Transit of Venus 2012 LIVE – Many Live Webcasts / Broadcasts (
    • TRANSIT OF VENUS 2012: Live Webcast (Multipoint) – by SWAN-India (http://www.skywatchersindia.
    • National Solar Observatory – Transit of Venus June 5–6 2012 (
    • The Transit of Venus, June 2012 (
    • 2012 Transit of Venus Live Webcast and chatroom with SEMS at UND live From Alaska (http://www.sems.
    • Transit of Venus 2012 online Simulator (
Article Sources and Contributors                                                                                                                                                                 12

    Article Sources and Contributors
    Transit of Venus  Source:  Contributors: Ahoerstemeier, Ajm81, Algocu, Allen234, Almccon, Andre Riemann, Andrew Bronx,
    Anita5192, AnonMoos, Anthony, Arc de Ciel, Arminius, Art LaPella, Arthur Rubin, Ast-hist001, AstroMalasorte, Astrochemist, Astrologist, Attilios, Aumakua, B.d.mills, Bankhallbretherton,
    Bender235, Bernardoni, BiT, BillC, Blake Burba, Bleiglass, BlueDome, BlytheG, Bob Burkhardt, Bobblewik, Bombyx, Bongwarrior, BornInLeningrad, Bowlhover, Br'er Rabbit, Brandmeister,
    Brian0918, Brighterorange, Brion VIBBER, CJLL Wright, CRGreathouse, Centrx, Ceoil, Chainsaw, Chris 73, Cirt, Ckatz, Closedmouth, Cmapm, CodeCat, Colonies Chris, Crazymonkey1123,
    Cuculcan2012, Curps, DJ Clayworth, DabMachine, Dangerous Angel, Danny, Darklilac, David Gerard, DavidCary, DavidStern, Delusion23, Diberri, Dioxinfreak, Diverman, DniQ, Doops,
    Doradus, Dpbsmith, DrKiernan, Dthomsen8, Duckypedia, Duckysmokton, Dusty78, ESkog, EastOfGingerTrees, Echuck215, Eddpayne, Eleassar777, Enirac Sum, Eu.stefan, Eurosong, Ezra
    Wax, Fotokannan, Fourthords, Frazzydee, Fredrik, Fæ, Gadfium, Gaius Cornelius, Geeoharee, Gestrgangleri, Ghalas, Giftlite, Goat212, Grr, Grutness, Guanaco, Hadal, Harryzilber, Headbomb,
    Hellbus, Hemanshu, Hike395, Hughhunt, Hytar, IceDragon64, Ilia Kr., JackofOz, Jagged 85, James McBride, Jan.Kamenicek, Jc3s5h, Jeltz, Jengod, Jim1138, Johnuniq, Jon186, Jonathan.kade,
    Jorge Iani, JorisvS, Joseph Solis in Australia, Jotempe, Jrockley, Kate, KayEss, Kbthompson, Kcpenner, Kevin McE, Kupos, Kwekubo, Lee M, Lethaniol, Lightmouse, LilHelpa, LtPowers,
    Luokehao, Lupin, Lwphillips, Lzz, MER-C, MK8, MacGyverMagic, Magister Mathematicae, Maias, Mandsford, Marijuanarchy, Marskell, Martarius, Materialscientist, Matt Crypto, Mattisse,
    Maximus Rex, Medeis, Michael Devore, Michael Hardy, MichalSadlon, Mike s, Minesweeper, Miranche, Mknight1229, Mr Stephen, MrJones, Ms2ger, Mshonle, Mswggpai, Mtcv, Mu301,
    NGerda, Neutrality, Niceguyedc, Novangelis, Oaklandguy, Oblivious, Oerjan, Optimist on the run, Orion 8, Oxymoron83, Pagrashtak, Pasachoff, Peterl, Pfortuny, Phe, Phil Boswell, Philip
    Trueman, Piledhigheranddeeper, PlatinumX, Pmokeefe, Purplegurlrox, Puzbie, RJHall, Radix37, Ranveig, Raul654, Raymondwinn, Rdhinakar, RedRabbit1983, Regardless143, Remember,
    RetiredUser2, Reywas92, Richerman, Rick7425, Rjwilmsi, Rjyanco, Roadrunner,, Robert Brockway, Robertgreer, Rominandreu, Ruslik0, Sam Hocevar, SandyGeorgia, Sardanaphalus,
    Saros136, Satori, Savage84, Schneelocke, Scwlong, Serendipodous, Sfahey, Sgm9000, ShardPhoenix, Shizhao, Shuipzv3, Shymian, Sinazita, Sj, SkyMachine, SocratesJedi, Softlavender, Softssa,
    Solipsist, Spark240, Speight, Spookpadda, Steve03Mills, SudhirP, Suruena, Sverdrup, Syncategoremata, Tassedethe, Tdadamemd, Telso, Tennjam, TheGiantHogweed, Theresa knott, Theseer,
    Thue, Thuvan Dihn, Tom, TomS TDotO, Tomruen, Tonyfaull, TracyRenee, Treisijs, Trick, TroyDCline, TypoDotOrg, UnitedStatesian, UtahSurfer, Vanished user 5zariu3jisj0j4irj, Vary,
    Vermeer, Vgent, Viriditas, Visor, Vivacissamamente, Vt-aoe, Wassermann, Wavelength, Wetman, WikiJon, Wile E. Heresiarch, WilliamKF, WilyD, Wkboonec, WolfmanSF, Yomangan,
    Yomangani, Youngwiki95, Yrodro, Zocky, Ævar Arnfjörð Bjarmason, 力 伟, 254 anonymous edits

    Image Sources, Licenses and Contributors
    File:Venustransit 2004-06-08 07-49.jpg  Source:  License: GNU Free Documentation License  Contributors:
    File:Transit diagram angles.png  Source:  License: Creative Commons Attribution-Sharealike 2.5  Contributors:
    Original uploader was Theresa knott at en.wikipedia
    File:Venus Tablet of Ammisaduqa.jpg  Source:  License: Creative Commons Attribution-Sharealike 3.0
     Contributors: User:Fæ
    File:Venus Transit & Parallax.svg  Source:  License: GNU Free Documentation License  Contributors: Vermeer,
    Duckysmokton, Ilia
    File:JeremiahHorrocks.jpg  Source:  License: Public Domain  Contributors: J. W. Lavender
    File:Venustransit 2004-06-08 07-44.jpg  Source:  License: GNU Free Documentation License  Contributors:
    ComputerHotline, Crux, Dbenzhuser, Duckysmokton
    File:1882 transit of venus.jpg  Source:  License: Public Domain  Contributors: Ahoerstemeier, CWitte,
    ComputerHotline, Crux, Duckysmokton, Enirac Sum, Tom
    File:20040608 Venus Transit.JPG  Source:  License: Public Domain  Contributors: Gestrgangleri
    File:BrownManchesterMuralCrabtree.jpg  Source:  License: Public Domain  Contributors: Manchester
    City Council.

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