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Astronomy Education Review / Volume 11 / Issue 1 / INNOVATIONS

2012, AER, 11 (1), 010203, doi:http://dx.doi.org/10.3847/AER2012035

The Hetu'u Global Network: Measuring the Distance to the Sun Using the June 5th/6th Transit of Venus

Published 30 November 2012

Jacqueline K. Faherty and David R. Rodriguez

Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile

Scott T. Miller

Sam Houston State University, Huntsville, Texas 77341-2267

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In the spirit of historic astronomical endeavors, we invited school groups across the globe to collaborate in a solar distance measurement using the rare June 5/6th transit of Venus. In total, we recruited 19 school groups spread over 6 continents and 10 countries to participate in our Hetu'u Global Network. Applying the methods of French astronomer Joseph-Nicolas Delisle, we used individual second and third Venus-Sun contact times to calculate the distance to the Sun. Ten of the sites in our network had amiable weather; 8 of which measured second contact and 5 of which measured third contact leading to consistent solar distance measurements of 152 ± 30 million km and 163 ± 30 million km, respectively. The distance to the Sun at the time of the transit was 152.25 million km; therefore, our measurements are also consistent within 1σ of the known value. The goal of our international school group network was to inspire the next generation of scientists using the excitement and accessibility of a rare astronomical event. In the process, we connected hundreds of participating students representing a diverse, multicultural group with differing political, economic, and racial backgrounds.

© 2012 The American Astronomical Society

KEYWORDS, PACS, and IPC

Keywords

distance measurement, physics education, Sun, transits, Venus, High School, College non-majors, Public Outreach, Solar System, History of Astronomy, Amateur astronomers and education

PACS

International Patent Classification (IPC)

  • G01B

    Measuring length, thickness or similar linear dimensions; Measuring angles; Measuring areas; Measuring irregularities of surfaces or contours

PUBLICATION DATA

ISSN

1539-1515 (online)

Publisher

$abstract.society.value is a Member of CrossRef The American Astronomical Society

ARTICLE DATA

History
Received 15 August 2012
Accepted 25 September 2012
Published online 30 November 2012
Digital Object Identifier
http://dx.doi.org/10.3847/AER2012035

    References

  1. Backhaus, U. and Breil, S. 2012, “Methods of contact times: Mathematical details,” http://www.venus2012.de/venusprojects/contacttimes/details/detailstimes.php.
  2. Forbes, G. 1874, The Transit of Venus, London, Macmillan and Co.
  3. Pasachoff, J. M., Schneider, G., and Golub, L. 2005, “The black-drop effect explained,” in Transits of Venus: New Views of the Solar System and Galaxy, IAU Colloquium No. 196, ed. D. W. Kurtz and G. E. Bromage, U.K. 242.
  4. Pasachoff, J. M. 2012, “Transit of Venus: Last Chance From Earth until 2117,” Physics World, 25(5), 36.
  5. Schneider, G., Pasachoff, J. M., and Golub, L. 2004, “TRACE Observations of the 15 November 1999 Transit of Mercury and the Black Drop Effect: Considerations for the 2004 Transit of Venus,” Icarus 168, 249.
  6. Short, J. 1761, “The observations of the internal contact of Venus with the Sun's limb, in the late transit, made in different places of Europe, compared with the time of the same contact observed at the Cape of Good Hope, and the parallax of the Sun from thence determined,” Philosophical Transactions of the Royal Society, 52, 611.
  7. Teets, D. 2003, “Transits of Venus and the Astronomical Unit,” Mathematics Magazine, 76(5), 335.
  8. Van Roode, S. and Mignard, F. 2012, “Transit of Venus: Local transit times,” http://transitofvenus.nl/wp/where-when/local-transit-times/.

Figures (7) Tables (1)

Figures (click on thumbnails to view enlargements)

FIG.1
As Venus transits across the surface of the Sun, observers in the Northern Hemisphere would observe Venus transit along a lower projection than observers in the Southern Hemisphere

FIG.1 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

FIG.2
A face-on view (bottom) of the Earth's and Venus's orbits and points of inferior conjunction, along with a side view (top) of their orbits, which demonstrates the 3.4-degree inclination of Venus's orbit. The dotted line denotes the line of nodes, where Venus's orbit crosses the ecliptic plane. If inferior conjunction occurs along the line of nodes, a transit will occur

FIG.2 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

FIG.3
Schematic diagram of the four contact points of Venus, as it transits in front of the Sun

FIG.3 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

FIG.4
A measurement of the impact parameter (p) as the Earth (the small circle) enters into the shadow of Venus (the large circle). The points of first and second contacts are shown

FIG.4 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

FIG.5
The shadow of Venus moves from right to left in this diagram during the times of first and second contact. The vertical grey lines correspond to values of constant x for the 2012 transit of Venus. (Figure used with permission from Backhaus and Breil 20121, at http://www.venus2012.de/venusprojects/contacttimes/details/detailstime.php)

FIG.5 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

FIG.6
Locations of school groups participating in a worldwide network to measure the Earth's distance to the Sun using combined observations of the transit of Venus, overlaid on a world visibility map for the transit of Venus (Figure used with permission from NASA at eclipse.gsfc.nasa.gov/OH/transit12.html). The red indicators mark the locations of the groups that were able to record the time of second contact and/or third contact

FIG.6 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

FIG.7
(a) Timing measurements of second Venus-Sun contacts taken around the globe (filled circles) along with the values expected for participating school groups where weather prevented viewing (open circles) as derived from van Roode and Mignard (2012)8. The best fit line to the data and calculated distance to the Sun with uncertainty using the respective contact times are displayed. (b) Timing measurements of third Venus-Sun contacts taken around the globe (filled circles) along with the values expected for participating school groups where weather prevented viewings (open circles) as derived from van Roode and Mignard (2012)8. The best fit line to the data and calculated distance to the Sun with uncertainty using the respective contact times are displayed

FIG.7 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

Tables

Table I. Second and third contact times observed across the world

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