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Solar System Transits


Transit of Mercury --||--Transit of Venus

Transit of Mercury

Next transit of Mercury: 9 May 2016

Simultaneous transits of Mercury and Venus will occur in the years
69,163, and
(from article Simultaneous Transits by J. Meeus and A. Vitagliano)

About Transit of Mercury — 2006 Nov 8: NASA 2006 Transit of Mercury page by Fred Espanek.

Webcasts of the transit of Mercury

Transit thumbnail
  • NASA Sun-Earth Day transit webcast - November 8,
    1:30 - 2:30 ET (10:30 -11:30 PT)
    • A panel of scientists live from NASAs Goddard Space Flight Center and educators and amateur astronomer live from Langley Research Center.
    • 2 NASA Explorer Schools connected for live interaction-questions and answers.
    • A telescope 'safety viewing' demonstration with instructions on how to view the transit using a classroom solarscope.
    • Live images of the transit from 2 NASA satellites, SOHO and TRACE.
    • Live ground based images from Kitt Peak and Hawaii!
    • Mercury transit Hawaiian style - live webcast from Hawaii
  • Exploratorium Webcast of Mercury Transit
  • Live webcast of the Transit of Mercury at NASA Digital Learning Network included discussion of the science, technology, and history of the transit as well as our knowledge of the Sun and space weather. The webcast included a panel discussion about Mercury, the Sun and safe viewing techniques of the transit. Live feed (provided by the Exploratorium) of the transit from Kitt Peak National Observatory near Tucson, Arizona, beginning at first contact.
  • Views of the Sun with SOHO

About the 2003 Transit of Mercury:

There are approximately 13 transits of Mercury each century. The planet Mercury passed in front of the Sun on Wednesday, May 7, 2003. Spacecraft and Earth-based observatories caught some nice views of the rare occurrence (transit). Here are images from the 2003 transit:

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.

See the Kepler Mission Transit of Venus poster, featuring a family portrait of the 2,326 Kepler planet candidates (as of 2011 Dec 5). The back has activities and information relevant to this very rare event.
Thumbnail of the Kepler Mission Transit of Venus poster

Transit of Venus

During the NASA Kepler Mission, a transit of Venus occurred June 5, 2012.

Venus Transit videos from NASA Solar Dynamics Observatory -

How to Safely View the Transit of Venus

  • The easiest way to view it is through safe "solar glasses" or "eclipse shades," the same filtered eye protection used by solar eclipse chasers. You can buy them through several vendors. See list of vendors under "Safely Viewing the Sun" below. Through these, Venus can only be seen as a small black dot, but they can also be used anytime to look for large "naked-eye" sunspots.
  • Binoculars or small telescope let you see the Venus transit much better, but one should never look directly through binoculars at the Sun! It takes only a fraction of a section for a magnified, concentrated image of the Sun to burn the eye. See the “how to use binoculars safely” video at (Doug Duncan), and try it out in advance, not on the day you need it to work.
  • Youtube video on how to observe the Venus transit safely by Paul Floyd — using solar viewing glasses or image projection using simple equipment.

How Often Do Venus Transits Happen?

If Venus and Earth orbited the Sun in the same orbital plane, transits would happen about every 1.6 years. However, the orbit of Venus is tilted with respect to Earth's orbit, so when Venus passes between the Sun and the Earth every 1.6 years, Venus usually is a little bit above or a little bit below the sun, invisible in the sun’s glare. So in reality, transits of Venus events happen in pairs. There have been only 6 transits of Venus sighted by humans since the possibility for such events was first realized in 1639 by British astronomer and cleric Jeremiah Horrocks. Here is list of transit of Venus pairs since the invention of the telescope:

  • 1631 (not witnessed) & 1639
  • 1761 & 1769
  • 1874 & 1882
  • 2004 & 2012

Notice each pair is 8 years apart, but in between pairs is over 100 years. The 2004 event was only 8 years before the 2012 one, but the one before 2004 was 121 ½ years before (1882). After 2012 it will be about 105 years before the next pair of transits occur, again separated by eight years. The repeating pattern is 121 ½ years, 8 years, 105 ½ years , 8 years. The next pair of Venus transits after 2012 will be 2117 Dec 11 and 2125 Dec 08.

Image below from Fred Espenek's 2012 Transit of Venus page.
global diagram of transit of Venus observability

During the transit on December 6, 1882, which made newspaper headlines all around the world, dozens of scientific expeditions were sent out across the world to observe it. Its importance to astronomers was that, by careful observation, they could use its motion and parallax to triangulate the distance between the Sun and Earth, thereby setting the scale for the entire solar system and the cosmos beyond. The 1882 transit of Venus gave astronomers the answer to this distance as 92,797,000 miles with an uncertainty of only 59,700 miles!

Photo by Slovak Union of Amateur Astronomers VT-2004 Team, Observatory Rimavska Subota, June 8, 2004, 05:40 - 11:00 UT, Rimavska Subota, Slovakia. Photo taken with 4/300mm teleobjective with AstroSolar filter, CCD camera SHT.

Transit of Venus Resources:

Image from Fred Espenek's 2012 Transit of Venus page
time diagram of the 2010 transit of Venus

Transit of Venus March , written by John Phillip Sousa in 1883, is available as a music file at 2004 Sun-Earth Day website. The Transit of Venus March was one of John Philip Sousa's earliest marches written while he was still a new conductor for the U.S. Marine Band - a commission that he had just accepted in 1880. Following a difficult year of recruiting new band members, and firing those that didn't satisfy his exacting musical standards, his band made its debut White House performance on January 1, 1881. Sousa's popularity as the 'March King' grew steadily in the years to follow. His better-known 'Stars and Stripes Forever' march was written in 1889 and was declared the official U.S. National March by an act of Congress in 1987.

John Philip Sousa was commissioned by the Smithsonian Institution to write a march to honor the great American physicist Prof. Joseph Henry who had died on May 13, 1878. The march was to be played as a processional for the planned unveiling of the commemorative statue of Henry. The statue was to be placed in front of the Smithsonian Institution in 1883. The December 6, 1882 transit of Venus was evidently such a striking event for the general public that Sousa chose to base the new march on this rare transit.

a poster depicting John Philip Sousa and aspects of the Transit of Venus

Some scholars also think that there may have been much more involved in this march than simple 'background music'. According to author David Ovason in his book 'The Secret Architecture of our Nation's Capital' (1999) the Transit of Venus March was to be performed at a specific time and date: April 19, 1883 at 4:00 PM. At this propitious hour, the planet Venus, invisible to the participants, would have completed its arc in the sky and would be setting in the west. Meanwhile, Virgo would rising in the east, and Jupiter would be directly over head. Venus was associated with the element copper. Joseph Henry had used large quantities of copper to create his powerful electromagnets, which at that time operated some of America's newest technology. The connection of the 'passing of Henry' commemorated by the statue, and the 'passing of Venus' in its western setting may have seemed like a fitting mystical bond between two separate worlds: human and cosmic.

In preparation for NASA's educational programs in 2004, Dr. Sten Odenwald, an astronomer at the NASA Goddard Space flight Center, examined the documents at the Library of Congress related to previous transits of Venus. He also worked with Ms. Susan Clermont to locate any music that may have been inspired by this rare celestial event. Among a collection of sheet music, they located Sousa's Transit of Venus March. Mr. Loris Schissel, a Sousa expert and the conductor of the Virginia Grand Military Band, was then contacted to inquire about the circumstances of this march.

About the transit of Venus - 2004

One of the major astronomical highlights of 2004 was the June 8 transit of Venus, an event that had last occurred in 1882. The complete transit was visible across Europe and most of Asia. At sunrise, people on the East Coast witnessed the rare movement of the planet Venus across the face of the Sun. This event had not been seen since 1882. Venus was over 67 million miles from the Sun and about 26 million miles from Earth--exactly between the Sun and Earth. Observers saw its small black disk "transit" across the Sun. See:

  • AAS paper on Transit of Venus: [12.01] Transit of Venus--2004: A Cosmic Opportunity, K. E. Kissell (University of Maryland and Kissell Associates), R. M. Genet (The Union Institute and University and Orion Institute)
  • European Southern Observatory (ESO) Transit page
  • Transit of Venus and ISS. Somewhere, someone will get to see the International Space Station transit the sun concurrent with the transit of Venus. Imagine looking at the sun while watching the transit when--zoom!--the ISS passes through your field of view.