August 21, 2017

The Great American Solar Eclipse

Naomi Pequette & Samantha Sands Earth & Space Science Programs Specialists

Have you seen an eclipse?

What’s going on?

Basic types of eclipses

Illustrations not to scale

Remember: Which One Gets Darker?

Why Don’t We Have an Eclipse Every Month?

Earth/Moon/Sun Orbital

Relationships

https://www.exploratorium.edu/eclipse/video/why-dont-we-have-an-eclipse-every-month

Why Don’t We Have an Eclipse Every Month?

Types of Solar Eclipses

Partial Annular Total

Cosmic Coincidence

The Sun’s diameter is 400x the Moon’s diameter, but the Sun is also 400x

farther away from Earth!

The Last Solar Eclipse on Earth

• The Moon gets 3.8 cm further away from Earth every year

• In 250 million years, Earth inhabitants will see the last total solar eclipse

Could Dinosaurs See a Total Solar Eclipses?

Could Dinosaurs See Total Solar Eclipses?

Angular Diameter of Sun: 1913 arcsec Angular Diameter of Moon: 2065 arcsec

Angular Diameter of Sun: 1917 arcsec Angular Diameter of Moon: 2049 arcsec

Angular Diameter of Sun: 1930 arcsec Angular Diameter of Moon: 2010 arcsec

Dawn of the Dinosaurs – 250 mya

Angular Diameter of Sun: 1930 arcsec Angular Diameter of Moon: 2010 arcsec

Mid Jurasic – 180 mya

To Watch the video- Check out the Galaxy Guide Portal

To Watch the video- Check out the Galaxy Guide Portal

The Partial Eclipse in Denver

The Partial Eclipse in Denver

https://eclipsemega.movie/simulator?lat=39.74752609999999&lng=-104.94280779999997

Viewing the Eclipse

• Projection of image • Pinhole or using tools

• Directly with filter

• Live streaming the event

https://www.youtube.com/watch?v=oX8UnDaJI2s (Start at 40seconds)

Watch the show safely!

Pinhole projection

Photo Credit: exploratorium.edu

Observing directly with filters Eclipse glasses

Not sunglasses!

#14 welders glasses

Use special care with filtered optics

Project the sun with tools – and care

What is DMNS Doing for the Day of the Eclipse?

• Safe Solar Viewing on Boettcher Plaza • Telescopes, binoculars, pinhole

viewers, eclipse glasses

• Eclipse Activities

• Face Painter with special eclipse design

• Space Odyssey Exploration Stations and Shows

• View Live Streams of the Eclipse

The First “Great American Solar Eclipse”

Myths and stories

Eclipse Predictions and the Maya

STEAM and the Eclipse

https://eclipse2017.nasa.gov/eclipse-art-projects

Predict the Corona Art Contest

Eclipse in Six

Eclipse Original Art Quilt

How Can You Share Information About the Eclipse with Guests Now?

Science on a Sphere Eclipse Datasets

Moon Phases Cart

The Gift Shop – resources and fun t-shirts and posters!

Sun., Aug. 6th Free Day Celebrating the Eclipse

Solar Telescopes

Resources Earth and Space Science Activity Kit: www.nisenet.org

Free Eclipse Online Course: https://www.coursera.org/learn/eclipse

Solar Eclipse Mythology:

http://news.nationalgeographic.com/news/2013/11/131101-solar-eclipse-myth-legend-space-science/ http://www.native-languages.org/legends-eclipse.htm

Eclipse Activity Kit: Eclipsekit.com

Live Streams of Eclipse:

• https://eclipse2017.nasa.gov/eclipse-live-stream

• https://www.exploratorium.edu/eclipse

Eclipse Glasses:

https://www.rainbowsymphonystore.com/collections/eclipse-glasses-safe-solar-viewers

http://www.thousandoaksoptical.com/ecplise.html

Solar Eclipse Math When Will the Last Total Solar Eclipse on Earth Happen?

https://eclipse2017.nasa.gov/challenge-13-%E2%80%93-last-total-solar-eclipse-earth

1. Find angular diameter of the Sun.

A=1930 arcseconds or ~0.5°

2. The diameter of the Sun is changing due to nuclear fusion. Verify equation for T=4.5 (today)

𝑑𝑆𝑢𝑛 = 1392000(0.0073𝑇2 − 0.028𝑇 + 0.98)

3. Convert the above equation to angular diameter

𝐴𝑆𝑢𝑛 =1392000(0.0073𝑇2 − 0.028𝑇 + 0.98)

𝐷

𝐴(𝑎𝑟𝑐𝑠𝑒𝑐) = 206265𝑑𝐷

DSun =149,000,000 km dMoon = 3,474km dSun,now = 1,392,000 km

4. DMoon=356,400km at perigee but is moving away at 3.8 cm/yr.

Create an equation to describe the diameter of the moon at time T.

Rate moving away in km/billion years: 38,000 km/billion yrs

What was DMoon at T=0 (4.5 billion yrs ago)? 𝐷𝑀𝑜𝑜𝑛,0 = 356,400 − 38000 × 4.5 = 185,400 𝑘𝑚

Final equation: 𝐷𝑀𝑜𝑜𝑛 = 38000𝑇 + 185,400

6. Convert that equation to angular diameter

𝐴𝑀𝑜𝑜𝑛 =𝑑𝑀𝑜𝑜𝑛

38000𝑇 + 185,400

Solar Eclipse Math When Will the Last Total Solar Eclipse on Earth Happen?

https://eclipse2017.nasa.gov/challenge-13-%E2%80%93-last-total-solar-eclipse-earth

The last eclipse will occur when Earth is 4.75 billion years old.

Or about 250 million years from now!

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0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 2.75 3 3.25 3.5 3.75 4 4.25 4.32 4.34 4.5 4.75 5 5.25 5.5

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Time Since Formation (Billions of Years)

Moon and Sun Angular Diameter

Angular Diameter of Sun (arcsec)