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Mystery Lab / Observation & interpretation

Blurred Marks and the Lines We Draw

Reduce the detail on the same board of marks, then add connecting lines. Explore what each of these two changes does.

Observation & interpretation · two guided observations

Why use a board of marks for the Martian canals story?

In the nineteenth century, observations of line-like markings on Mars led to interpretations involving artificial waterways. But the appearance of a mark and the explanation attached to it are different things.

Here, an original board of dark marks takes the place of Mars. First display it with less detail, then switch on colored connecting lines separately. Check whether the original marks have changed or only their display has changed.

First move the slider and compare the bright gaps and edges between the marks. Then switch the connecting lines on and off: have the original dark marks changed too?

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Continue with the story and its records

Explore how the difference you noticed connects with the surviving records of the historical story.

Read the Martian canals story
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Sources and scope

This reading brings together institutional accounts of astronomical history and NASA’s mission records. Historical maps, manuscripts and photographs are not reproduced. Follow the links to explore the institutions’ materials.

  1. 01
    Percival Lowell’s Search for Life on Mars Lowell Observatory · Checked 2026-10-22
  2. 02
    Schiaparelli e la vita su Marte INAF · EduINAF · Checked 2026-10-22
  3. 03
    Mars Mariner Missions NASA · Checked 2026-10-22
  4. 04
    Did you know that… Schiaparelli influenced science fiction? INAF · Museo Astronomico di Brera · Checked 2026-10-22
  5. 05
    Triumph of Mariner 4 NASA · Checked 2026-10-22
  6. 06
    Mariner 9 NASA · Checked 2026-10-22

The text and diagrams were created after reviewing these sources. The explanatory model does not reconstruct Martian terrain or historical observing equipment, nor does it explain every cause of the canal theory. It does not assume that everyone sees the same lines.