Vernier Software and Technology
Vernier Software & Technology
Tech Info Library

Dave's Eclipse Tips

Dave Vernier in the Australian Outback collecting data during a 2002 total solar eclipse with a very old laptop and a Palm Pilot

Tip Number 1: Eye Safety
Never look directly at the sun, except if you are in a place where the eclipse is total and then only during the minute or two that the sun is completely blocked by the moon. It is not that the sun is more dangerous than usual to look at during the partial eclipse; it is just that the sun puts out more energy than your eye can handle. Here is a good link to eye safety tips from NASA:

Tip Number 2: Safe Ways to Look at the Sun
Solar Glasses
During the partial phase of the eclipse (or really any time) you should look at the sun only through special filters or glasses designed specifically for that purpose. Sometimes people call these glasses "eclipse glasses", but that is perhaps confusing because during the few moments of the total eclipse (only) you can remove them. Perhaps a better name is "partial eclipse glasses". Wear the glasses to look at the sun in the time leading up to the total eclipse, take them off for the moment or two of totality, then put the glasses back on.
We gave out thousands of these glasses at the National Science Teachers Association conference in March. We are selling teacher packs of 40 eclipse viewing glasses for $16. See the Vernier eclipse page for more information:

Do not use welding glasses or any other dark glasses, unless they are specifically made for looking at the sun.

Solar Projectors
Another way to indirectly watch the eclipse is to make a solar projector. These systems project the image of the sun on a white screen, and you can safely look at it as much as you like. There are lots of great plans for how to set this up on the internet. See, for example:

Tip Number 3: What to Expect on the Day of the Eclipse
A total eclipse is a rare thing. There has not been one in the continental United States for almost 40 years. If possible, travel to a place where you will be in the path of totality. Here is a link to a state-by-state collection of maps of the path of totality:

If you are in the region of totality, eclipse day will be a day you will never forget. It feels like the end of the world; it is getting dark in the middle of the day. You can look at the sun and see a strange glow around it. Perhaps you will also see loops of hot gasses streaming off of it. The temperature may drop, and it may get windy. People may cry, scream, shout, and celebrate. Animals may do strange things. Here are links to websites with information on eclipses, including videos that may give you some idea of what the experience is like:

Plan ahead for eclipse day, and make sure you leave lots of time to get to the location you have selected. There will be lots of people traveling to the zone of totality, and there may be major traffic jams.

Remember that you will probably be out in the sun for hours on this day. Wear sunscreen and a hat. You should probably plan to be at a location with some shade and rest room facilities.

It will take over an hour for the moon to gradually block more and more of the sun. During this time, you can observe the sun through your eclipse glasses or with a projection system. This is also a good time to set up data-collection equipment (see the next tip). Finally, it will start to get very dark, and when the sun is completely blocked by the sun, you can take off your eclipse glasses and look directly at the sun for a brief period. Totality will last about two minutes, but the duration will vary by location. The brightness of the sky will dim to a point where Venus and Jupiter start to become visible. You will see what is called the Diamond Ring (the first rays of light from the sun sneaking by the side of the moon). This signals that it is time to put the eclipse glasses back on. You will be surprised how many people start talking about going to another eclipse.

If you want to sound knowledgeable about the eclipse, familiarize yourself with these terms:
* First Contact, Second Contact, Third Contact, Fourth Contact
* Sunspots
* Corona
* Prominences
* Bailey's Beads
* Diamond Ring

For a good collection of videos and other information on what to expect on eclipse day, visit

Shadow Bands
Here is a good introductory 30-minute video from NASA on the eclipse:

Tip Number 4: Data Collection During the Eclipse
If you read about eclipses (several good references are listed below), you will find people often report:
* The temperature drops as the eclipse proceeds
* The wind speed increases as totality approaches
* The sky gets bluer as totality approaches

Will all of this really happen? It is a great time to take some data!

Note that you will have lots of time to take data. It takes at least an hour from First Contact, when the moon first starts obscuring the sun until totality (or the peak of the partial eclipse, if you are not in the zone of totality). You then have the same amount of time after the eclipse until the sun is completely unblocked. Plan your data collection accordingly.

We encourage you to collect data and send it to us. In the Fall 2017 Caliper newsletter, we will share some of the most interesting results. It will be interesting to compare data taken by different student/teacher groups in different regions of the country. You can also post data and results on social media with the hashtag #VernierEclipse

The tips below have more suggestions on collecting light, temperature, and wind speed data during the eclipse.

Tip Number 5: Studying Light Level During the Eclipse
As the moon gradually blocks more and more of the sun, you would certainly expect to see an associated change in the light level. The sun puts out so many different kinds of light, it would be interesting to see how any of the following change:
* Visible light level measured with our Light Sensor (LS-BTA) or Go Direct Light and Color Sensor (GDX-LC)
* UVA measured with UVA Sensor (UVA-BTA) or Go Direct Light and Color Sensor (GDX-LC)
* UVB measured with UVB Sensor (UVA-BTA) or Go Direct Light and Color Sensor (GDX-LC)
* Total solar radiation with our Pyranometer (PYR-BTA)
* Light color with our new Go Direct Light and Color Sensor (GDX-LC)

If you monitor any of those parameters, it will be interesting to see how the level changes in relationship to the fraction of the sun blocked. Is there be a direct relationship between the reading and the fraction of the sun that is visible?

One complication that may be the presence of clouds. Here are some data collected using our very old MultiPurpose Lab Interface program (MPLI) in 1991 during a total eclipse in Louisiana by Jim Giammanco of Louisiana State University. At the peak of the eclipse about 30% of the sun remained visible, and the light level dropped a similar amount. After the peak of the eclipse clouds moved in. (Beware that sometimes the cooling during an eclipse causes cloud cover to change.)


One more tip on data collection: You and your students will be very excited during totality and the time just before. It is easy to make mistakes in that situation, so practice taking data in a "trial run" before eclipse day.

Tip Number 6: Emission Spectra During the Eclipse
You often hear that the sky gets bluer as totality approaches during an eclipse. Is it really true? With a spectrophotometer set up to capture the light from the sun, you could do an interesting study of this. Note that you will have lots of time to take data. It takes at least an hour from First Contact, when the moon first starts obscuring the sun until totality (or the peak of the partial eclipse, if you are not in the zone of totality). You then have the same amount of time after the eclipse until the sun is completely unblocked. Plan your data collection accordingly.

If you have a spectrophotometer that can plot emission spectra, such as our Vernier Emission Spectrophotometer (VSP-EM) with its optional Vernier Emissions Fiber (VSP-EM-FIBER) or a Go Direct SpectroVis Plus Spectrophotometer (GDX-SVISPL) with its Vernier Optical Fiber (VSP-FIBER), you can take an emission spectrum every few minutes as the eclipse proceeds and compare.

Here are some data we took on a (rare) sunny day in March in Oregon. There was no eclipse going on, but we did this to document some suggestions on how to take solar spectra. If you plan to take emission spectra data during the eclipse, you should definitely practice on a sunny day well before the eclipse. These data were taken using the Optical Fiber that comes with the spectrophotometer and pointing the fiber down at a piece of white paper on the ground. By varying the distance from the paper to the Optical Fiber, you can vary the intensity of the spectrum.

Sample solar spectrum made using the Vernier Emission Spectrophotometer

Sample solar spectrum made using the Vernier SpectroVis Plus

While collecting data with the SpectroVis Plus, the sample time was changed to 15 ms from the default 50 ms to avoid maxing out the reading at some wavelengths. To do this, choose Set Up Sensors from the Experiment menu. Choose the spectrophotometer, and then change the sample time.

Note that the emission spectrum you see plotted is not a calibrated emission spectrum. That is, because the intensity at wavelength A is double the intensity at wavelength B, we cannot say that the energy delivered at wavelength A is double that delivered at wavelength B. The intensity is really a combination of how much light there is at that wavelength and how sensitive the detector is to that wavelength. On the other hand, if you always use the same instrument, you can compare the relative intensities at different wavelengths. For example, the widely reported phenomenon of the sky turning bluer as the eclipse approaches totality should show up in these spectra. The relative height of the blue intensities should increase as compared to the red wavelength intensities.

Tip Number 7: Studying Temperature Changes During the Eclipse
We have several different temperature sensors you could use for monitoring the temperature during the eclipse. Any will work, but since we are interested in air temperature in this case, a sensor that responds quickly to changes in air temperature would be best. Our Surface Temperature Sensor (STS-BTA) will work best for this application.

Another option would be to use a FLIR ONE Infrared camera with the Vernier Thermal Analysis Plus app for iOS. This app allows you to make time-lapse video with temperature recorded. Consider collecting a time-lapse video showing the viewing area with some people occasionally in the video but also (perhaps) showing changes in surface temperatures as the eclipse proceeds.

Tip Number 8: Studying Wind Speed During the Eclipse
During a total eclipse you often get changes in temperature. Along with that there can be wind changes. There are two ways you might approach studying this:
Use our hand-held Anemometer (ANM-BTA). This Anemometer measures wind speed in one direction only. If you use it for monitoring wind speed, you should assign a person to hold it and orient it so that it points into the wind.

Another option is to bring along a complete weather station, such as the Vantage Vue Weather Station (DWVUE). This station can function entirely on batteries and is not too big and bulky to move around. Mount the weather sensor unit somewhere high like on top of a car.. The anemometer on this unit automatically measures the wind speed and direction.

The Vantage Vue Console displays a 2-minute and a 10-minute average wind speed. It also indicates the 10-minute dominant wind direction. You would probably want to have someone write these down as the eclipse proceeds. The console even has a built-in light making it easy to read during totality.

Tip Number 9: Eclipse Photography
There are a number of articles on eclipse photography on the web. See, for example:

To summarize the notes on these websites:
* First, make sure that you never look through a camera directly at the sun. Don't even point your camera toward the sun, without a solar filter on it. You could damage your eyes.
* Bring a tripod and use it.
* Except during the brief period of totality, only photograph the sun through a filter designed specifically for that purpose.
* During totality, do not use a filter.
* Use a long focal length lens, or the sun will be too small.
* Consider taking photos or even a video of the excited people around you during the eclipse.
* One bit of advice you may get from experienced total eclipse viewers is that you just should not bother trying to take photos or videos during the precious two minutes you have for totality. The tremendous variation in light levels before and during the eclipse make photography difficult. It is probably best to let the professional photographers take the photos; you can enjoy them later. During the eclipse, just enjoy the experience.

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