Solar Corona Inquiry for Blind and Low Vision Learners
This activity is intended for Blind and Low Visions learners with access to a screen reader that can translate text to speech.
The language below is designed to accompany the hands-on experience of a set of seven thermoform tactile art representations of the solar corona through human history. Please contact firstname.lastname@example.org to obtain this set of thermoform tactiles until we are able to make them available in a more sustainable manner.
By using this set you will be empowered to evaluate this hypothesis:
Is this petroglyph created on a sandstone wall in Chaco Canyon by Ancestral Pueblo people an impression of the 1097 total solar eclipse during a time of high solar storminess called "Solar Maximum”?
Of course we can never know for sure whether this is a correct interpretation of the petroglyph, but we can learn a lot about ancient and modern solar observation in the process of exploring this hypothesis.
Descriptions of thermoform tactiles
1097 hypothesis - Sandstone petroglyph in Chaco Canyon
This is a thermoform tactile art representation of a sandstone petroglyph in Chaco Canyon. A petroglyph is a figure that is carved or pecked into a rock surface.
Ancestral Pueblo people who were resident in Chaco Canyon about a thousand years ago created this petroglyph. In real life, the petroglyph is about eight inches across, which is about the distance between thumb to pinky with fingers spread wide on an adult human hand.
Explore. How would you describe this petroglyph? What are its features, shapes, and textures? Is there more than one part to the petroglyph? Explore to the upper left.
How would you interpret the petroglyph? What might it be representing?
A person’s interpretation of the petroglyph depends a lot on their individual prior experience and knowledge, whereas a description of the petroglyph is something we could all observe and agree upon.
One possible interpretation of this petroglyph is that it represents the total solar eclipse of July 11, 1097. A total solar eclipse occurs when the Moon passes in front of the Sun, completely blocking the bright light of the solar disk. For a few minutes, during totality, human eyes can perceive the glow of the Sun’s outermost atmosphere called the solar corona. If there is a solar storm in progress during this time the rays of the solar corona might be curled or distorted in some way.
Could this peculiar petroglyph be an impression of a total solar eclipse during a time of high solar storminess that we call "Solar Maximum”? We know there was a total solar eclipse visible over Chaco Canyon on July 11th, 1097 during a time of high human activity in Chaco and the surrounding region.
Does this petroglyph represent an impression of the solar corona that Chaco residents witnessed in the sky for about 4 minutes in the mid-afternoon? Was 1097 a time of high solar activity, making a solar storm more likely to have occurred during the eclipse? Would they have been inspired to record this special celestial event in rock art?
Of course we cannot ever know for sure whether this is a correct interpretation of the petroglyph, but we can learn a lot about ancient and modern Sun-watching in the process of exploring this hypothesis. Independent research suggests that 1097 was, in fact, during a period of maximum storminess on the Sun. Is the ancient petroglyph design consistent with what we know today about what a stormy corona looks like?
Let’s start by learning more about Chaco Canyon.
Chaco Canyon is a World Heritage site located in northwestern New Mexico. The descendants of the Ancestral People still live in the diverse modern Pueblos of the US Southwest, including Acoma, Hopi, Laguna, Zuni, and many more.
The Canyon is renowned for ancient architecture aligned to the Sun and Moon cycles, and for its evidence of ancient Sun-watching techniques to track time and to mark culturally important times of year. Such techniques include the use of sunrise or sunset horizon markers or the use of shadow & light displays on spiral petroglyphs.
This Chaco petroglyph is located near to places where there is strong evidence of ancient Sun-watching. There are also many other carvings located on the same rock face as this petroglyph, including flute players, a four-legged animal, and other human-like figures.
Every 11-years the Sun has a peak of solar storminess called Solar Maximum. In between the peaks there is a time of low solar activity called Solar Minimum when solar storms are less likely.
How might solar storms appear in the solar corona? And how can we tell the difference betweenAnd how can we tell the difference between a solar corona during solar minimum and a solar corona during solar maximum?
1860 - Hand drawing of total solar eclipse
This is a hand drawing of a total solar eclipse near a period of solar maximum activity. It was made by Guglielmo Ernesto Tempel while observing the eclipse on July 18, 1860 from Torreblanca, Spain.
In 1859, just one year before this eclipse, the Sun released the most powerful solar storm ever recorded, the so-called Carrington Event.
Explore the streamers of the solar corona in this hand-drawing. Can you find a shape that may represent a solar storm? Where is this feature located in the drawing?
Similar curved shapes are sometimes observed in modern photography of the corona. The oval-shaped feature is now known to be characteristic of the core of a solar storm that we now call a Coronal Mass Ejection or C-M-E for short.
A C-M-E can curve or otherwise distort the rays of the solar corona, but we did not know about this type of solar storm in 1860 when this hand drawing was made. It was more than 100 years later when spacecraft images first revealed that tons of solar material could be violently ejected from the Sun. It took longer to confirm that a C-M-E could appear like this oval shape while it was leaving the Sun’s corona.
Could one or more Coronal Mass Ejections be related to interpreting the Chaco petroglyph?
1918 - Painting of total solar eclipse
This is a scientifically accurate oil painting of a total solar eclipse near solar maximum. It was made by Howard Russell Butler based on his observations on June 8, 1918 from Baker, Oregon.
Explore around the Sun’s disk. Can you find small, raised features called solar prominences? Prominences are MUCH smaller than coronal streamers and Coronal Mass Ejections.
Find the magnified prominence on the thermoform. Feel its curvy shape and structure. Mr. Butler sketched and later painted this solar prominence after observing the prominences through binoculars during the eclipse.
Solar prominences hover in the Sun’s atmosphere, but they generally do not leave the Sun unless a Coronal Mass Ejection occurs to send the material erupting into space.
Could solar prominences be related to interpreting the Chaco petroglyph? Maybe the curlicues of the petroglyph are not necessarily to scale, but an impression of what the Chaco residents saw? During the 1097 eclipse, maybe there were solar prominences all around the Sun that somehow appeared larger and more striking at the time?
1980 - Ground-based photograph of total solar eclipse
This is a ground-based photograph of a total solar eclipse near a 3-year period of solar maximum when solar storms are most likely to occur. The photo was made by an expedition team from the High Altitude Observatory - a famous scientific research lab devoted to studying the Sun. The team observed the eclipse on February 16, 1980 from Palem, India.
Explore the coronal streamers emerging from all around the Sun
Compare what you feel to the shape of the corona in the 1994 thermoform at a time of solar minimum. What is the difference?
1994 - Ground-based photograph of total solar eclipse
This is a ground-based photograph of a total solar eclipse near a period of solar minimum when solar storms are less likely to occur. The photo was made by an expedition team from the High Altitude Observatory - a famous scientific research lab devoted to studying the Sun. The team observed the eclipse on November 3, 1994 from Putre, Chile in South America.
Feel the shape of the solar corona during this time of minimal solar activity. Are coronal streamers all around the Sun? Where are they?
Compare the shape of the corona during solar maximum in the 1980 thermoform to the shape of the corona during a minimum of solar activity on this thermoform. What is the difference?
Can you feel how during solar minimum, the coronal features are not extended out in all directions around the Sun, but are instead emerging out the sides only?
How can the difference between the structure of the solar corona at solar minimum and solar maximum be used to help interpret the Chaco petroglyph? Do the features of the petroglyph support 1097 as a time of solar minimum or solar maximum? Why?
1996 - NASA spacecraft image of Sun’s corona
This is a NASA spacecraft image of the solar corona made in 1996.
The inner ring represents the scaled size of the Sun. The outer ring represents the field of view blocked by the spacecraft instrument known as a coronagraph so that we can observe the corona at any time, not just during natural eclipses on Earth.
The NASA spacecraft is called the Solar and Heliospheric Observatory or SOHO, for short. The SOHO coronagraph images are very useful, however they are unable to observe the part of the corona that is nearer to the Sun.
In this 1996 SOHO image are coronal streamers extending out in all directions around the Sun? Given what you learned from comparing the structure of the corona you are feeling, would you say that the year 1996 was during a period of Solar Minimum or Solar Maximum?
2000 - NASA spacecraft image of Sun’s corona
This is a NASA SOHO spacecraft image of the solar corona made in 2000.
The inner ring represents the scaled size of the Sun. The outer ring represents the field of view blocked by the spacecraft instrument, creating an artificial eclipse.
Compare this image to one in 1996. Is there coronal structure emerging from all around the Sun? Notice that some streamers have become brighter storms ejecting material from the Sun. Can you find two Coronal Mass Ejections? Where are they located in the image?
Given the structure of the corona you are feeling, would you say that 2000 was during a period of Solar Minimum or Solar Maximum?
How can the difference between the structure of the solar corona at solar minimum and solar maximum be used to help interpret the Chaco petroglyph?
Do the features of the petroglyph support 1097 as a time of solar minimum or solar maximum? Why?