Fulldome Eclipse Animations from Rice University

With the Great American Eclipse of 2017 fast approaching, many planetariums are looking for content elements to use in local programming about eclipses. Rice University, supported by a grant from NASA’s Heliophysics Education Consortium, has developed a collection of fulldome eclipse visualizations from a variety of perspectives which can help audiences better understand the spatial relationship between the Sun, the Moon, and the Earth during a solar eclipse.

Here’s a sample:

 

For the convenience of SciDome users, Spitz has rendered these visualizations into the proper media formats and codecs for SciDome systems. To access these clips, contact Chris Seale at cseale@spitzinc.com for download information — we need to collect your information first so we can pass it on to Rice for their grant reporting purposes.

Edison’s “Tasimeter” and the Eclipse of 1878

Witnessing a total solar eclipse could change your life. Unpredicted eclipses have changed the progression of historical events. The unexpected environmental effects of a sudden darkness at midday can be very unsettling to people and animals alike.

On July 29, 1878, Thomas Edison observed the total eclipse of the Sun as part of Henry Draper’s Expedition to Rawlins, Wyoming Territory. (Although this year’s total eclipse will pass through Wyoming, the City of Rawlins will be some distance south of the total path this time.) Edison was there to test a new invention that could detect infrared light and estimate the temperature of objects remotely, and he planned to try and estimate the heat of the Sun’s corona while the solar photosphere was blocked by the Moon.

Edison’s preparations for the eclipse were not as cautious as they should have been. Because total eclipses happen close to home so very rarely (2017 is the first year that the totality has appeared in US skies since 1979), and due to the practicalities of 19th century life, most astronomers arrived at the observing site early to uncrate their heavy observing equipment and build observing shacks, and mix concrete to make steady piers. Edison arrived with a few days left before the eclipse, without time to build a protective structure, so he used the existing shelter provided by a chicken coop. On eclipse day, as the sky darkened, the bewildered chickens literally came home to roost, disrupting his observations.

Illustration of Edison’s Tasimeter

Edison named the infrared-detecting device his “tasimeter”, and he was trying to break ground in a new scientific field in competition with the director of Pittsburgh’s Allegheny Observatory, Samuel P. Langley. Instead of letting Langley test the tasimeter’s eclipse performance alongside more proven devices such as the thermopile, Edison tried to “scoop” the competition with his solo work, and failed.

Although Langley also failed to estimate the heat coming from the solar corona with his thermopile, less than a year later he had invented the first bolometer, which is commonly used today in its most refined designs. Langley’s bolometer was so sensitive that it could detect the heat produced by a cow from a quarter of a mile away.

Although the temperature of the Sun’s corona has since been measured with bolometers, the reason why it is so hot – about 1.5 million Kelvin, considerably hotter than the Sun’s surface (5800K) – remains a theoretical problem in physics to this day.

Therefore, if you want to simulate an eclipse, or to prepare for the real thing, don’t neglect the auditory experience. Consider all possible distractions that could disrupt observations in advance, and avoid them. If you are standing near a farm in Wyoming, as the darkness approaches the sound of confused barnyard animals will reach a crescendo.

The new book American Eclipse offers a more in-depth view of the Solar Eclipse of 1878, following the trevails of Edison, planet hunter James Craig Watson, and astronomer Maria Mitchell.

Sources:
“On the Total Solar Eclipse of July 29th, 1878”, George F. Barker, Proceedings of the American Philosophical Society, Vol. 18, pp. 103-113, 1878. ( https://archive.org/details/jstor-982766 )

“Eclipse Vicissitudes: Thomas Edison and the Chickens”, J. Donald Fernie, American Scientist, Vol. 88, No. 3, May-June 2000. ( http://www.americanscientist.org/issues/pub/2000/3/eclipse-vicissitudesthomas-edison-and-the-chickens/1 )

The Total Solar Eclipse of 2017 in SciDome

Total Solar Eclipse

The appearance of a total solar eclipse is so singular that it is impossible to appreciate it without having seen it for oneself. Unexpected eclipses have changes history in the past, although they can now be predicted. Even having an eclipse forecast in hand does not reduce the impact of the experience on witnesses.

And total eclipses are rare. The most recent time the moon’s shadow fell properly across the United States was in February 1979.

But just as eclipses can be predicted, they can also be simulated in the SciDome planetarium environment. Here is how to simulate the upcoming Great American Eclipse of August 21st, 2017 in your dome.

First you need to set the correct date in Starry Night Dome. Starting from the home location of your planetarium, if you are located in the United States, some time on August 21st the Sun will be at least partially eclipsed, but it probably won’t be totally blocked out.

An accurate simulation of a partial eclipse in SciDome without any magnification will probably look like a normal day as the Sun moves from the eastern to the western horizon across the blue sky and sets. Likewise, in the real world it is possible to not notice the progress of a partial solar eclipse unless the fraction of Sun covered is well over 50%. The shadows cast on the ground by sunlight shining through tree-leaves can reveal a partial solar eclipse, but the reduced amount of sunlight in the sky is only subtly perceptible.

Two steps need to be taken to appreciate a partial solar eclipse in SciDome. First, use the keystroke [Ctrl-D] to toggle daylight off. This will improve the contrast between the Sun and the black sky background.

If you are close to the zone of totality, looking at a hemispheric view, the blown-up image of the Moon we normally use in SciDome to show its phases will probably appear to cover the Sun totally during the partial phases, and toggling daylight back on again with the same keystroke will show that the remaining sunlight is still illuminating the sky above your location. Therefore please right-click on the Sun and select “Magnify”. This will center the Sun on the front of the dome and magnify it so that it’s zoomed in. In this way the “Enlarged Moon” effect used at wide fields of view is eliminated. Now the “bite” out of the Sun is properly simulated. Run time forward and back in steps of up to 300x actual speed to follow the event from start to finish.

To simulate the total phase of this solar eclipse, identify an observing site that will be in the zone of totality. Because the path will neatly bisect the United States, the nearest place where the eclipse will be total is never more than three states away from your location (excepting New England.)

Path of the 2017 Total Solar Eclipse

The following state capitals will be in the zone of totality:

  • Salem OR
  • Lincoln NE
  • Jefferson City MO
  • Nashville TN
  • Columbia SC

Major cities including Kansas City, St. Louis, and Charleston will also be in the zone. You can find alternate locations with the interactive Google Eclipse Map.

Hit the “Viewing Locations” button and enter the name of the town, or its latitude and longitude, or its ZIP code. Once Starry Night has “flown to” your destination, the northern horizon will probably be on the front of your dome, but you can still right-click and “Center” the field of view on the Sun without magnification, and then step forward and back in time in intervals of hours or minutes to find the moment when the sky starts to incrementally darken. The keystroke to advance in 1-hour steps is “h”, and to reverse in 1-hour steps is [Shift-h]. To advance in 1-minute steps, use the “t” key, and to reverse in 1-minute steps, just add the [Shift] key.

Starry Night will not appear to display other than a normal daylight sky until about 8 minutes before totality. During those 8 minutes the sky will start to appear darker and more violet, and extra objects will start to appear in the sky: Venus first, followed by the brighter stars. Then the darkening will accelerate and go into totality for up to 160 seconds of simulated time. The horizon will accurately represent the eerie appearance of the “360° Sunset”, and the occulting Moon will reveal the red solar chromosphere and the white corona surrounding it. After totality is finished, the appearance of the unmagnified sky will take about 8 minutes to return to normal. The partial phases and totality can be simulated accurately with magnification.

Shadow cones, a Starry Night feature to illustrate eclipses

Because SciDome can also accurately simulate travel through space, right-click on the Sun during the eclipse and select “Go there”. Without specifying a surface location, Starry Night will arrive at a point somewhere above the Sun’s surface, with no Earth or Moon in sight. Type in “Earth” in the Find Pane’s search engine field, and then you can right-click on it and select “Magnify”. The disk of the Earth should appear centered on the dome with the far side of the Moon superimposed on it, with the Moon’s shadow being cast on the United States below. By right-clicking on the Moon and selecting “Shadow Cones”, the dimensions of the shadow falling on the Earth will be demonstrated. Step forward and back in time with “t” to see the shadow move across the disk of the Earth.

Right-click on the Moon again and select “Orbit” to show the Moon’s orbital path falling in front of and behind the Earth from this observing location near the Sun. Zoom out a couple of degrees to see the whole arc of the Moon’s orbit to the left and right of the Earth. The keystroke “m” and [Shift-m] can be used to step forward and back by intervals of months, demonstrating that the Moon’s orbit is slightly tilted such that it rarely creates the perfect syzygy between the Earth and Sun to create a solar eclipse.