Mercury Transit across the Sun, 7 May 2003

From: Amara Graps (amara@amara.com)
Date: Fri May 02 2003 - 06:47:45 MDT

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    Transits in General
    http://sunearth.gsfc.nasa.gov/eclipse/transit/transit.html

    Mercury transit
    http://sunearth.gsfc.nasa.gov/eclipse/OH/transit03.html

     From the above web page:

    "2003 May 07: Transit of Mercury

    The transit or passage of a planet across the face of the Sun is a
    relatively rare occurrence. As seen from Earth, only transits of
    Mercury and Venus are possible. On the average, there are 13
    transits of Mercury each century. In comparison, transits of Venus
    occur in pairs with more than a century separating each pair.

    On Wednesday, 2003 May 07, Mercury will transit the Sun for the
    first time since 1999. The entire event will be widely visible from
    the Europe, Africa and Asia as shown in the map in figure 1. Japan
    Australia, and New Zealand will witness the beginning of the transit
    but the Sun will set before the event ends. Similarly, observers in
    western Africa, eastern North America and eastern South America will
    see the end of the event since the transit will already be in
    progress at sunrise from those regions.

    The principal events occurring during a transit are conveniently
    characterized by contacts, analogous to the contacts of an annular
    solar eclipse. The transit begins with contact I which is the
    instant when the planet's disk is externally tangent with the Sun.
    Shortly after contact I, the planet can be seen as a small notch
    along the solar limb. The entire disk of the planet is first seen at
    contact II when the planet is internally tangent with the Sun.
    During the next several hours, the silhouetted planet slowly
    traverses the brilliant solar disk. At contact III, the planet
    reaches the opposite limb and once again is internally tangent with
    the Sun. Finally, the transit ends at contact IV when the planet's
    limb is externally tangent to the Sun. Contacts I and II define the
    phase called ingress while contacts III and IV are known as egress.
    Position angles for Mercury at each contact are measured
    counterclockwise from the north point on the Sun's disk. "

    -- 
    ********************************************************************
    Amara Graps, PhD          email: amara@amara.com
    Computational Physics     vita:  ftp://ftp.amara.com/pub/resume.txt
    Multiplex Answers         URL:   http://www.amara.com/
    ********************************************************************
    "Oh you damned observers, you always find extra things."
        -- Fred Hoyle [quoted by Richard Ellis at IAU Symposium 183]
    


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