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# homeschoolsciencegeek

### August 2019

The second high school class focused on units and distances used in Astronomy.  I started class with a lecture on constellations (Chapter 2-1 in Foundations of Astronomy) and how  they started out has stories in the sky but are now considered sections of the sky, just like states are sections of the United States.  If you tell someone you went to a museum in Ohio, most people will have a general idea of where you went.  Likewise if you tell an astronomer you are studying a star in Orion, they will know what part of the sky you are looking at.  We talked the difference between linear diameter (the diameter of a circle, like a 16″ pizza which is 16″ across at the widest point) and angular diameter.  I used a large ball to demonstrate that when the ball is close to me, the angular diameter of the ball could be quite big but as we moved it further away, the ball appears smaller so its angular diameter gets smaller.  So the angular diameter depends on the distance from the object.  We used the small angle formula to calculate the angular diameter of the moon and the sun, which both come out to about 1/2 a degree.  Even though the sun is much bigger than the moon, it appears to be the same size because its so much further away.  The sun and moon are the biggest objects in the sky and they aren’t even a degree across, so we need smaller units for talking about the angular diameter of other planets and stars.  1 degree  = 60 arcminutes and 1 arcminute  = 60 arcseconds.  So in astronomy you will frequently see angular sizes listed in arcseconds.

The lab activity involved using parallax to measure the distance to an object (Ch 9-1 in Foundations of Astronomy) and is one of the activities on BHP.  If you close one eye and hold up your thumb so it is covering a distant object, say a lamp, then close the eye you had open and open the other eye, you will see your thumb ‘jump’.  This apparent shift in position is because of the distance between your eyes.  The bigger the distance between observation points (your eyes in this case), the bigger the parallax.  This distance between observation points is called the baseline.  When we’re measuring the parallax of stars we use the baseline of the earth’s orbit around the sun – observing stars 6 months apart so that the earth is at opposite ends of its orbit.    Crash Course Astronomy has a nice video on distances in astronomy:

I placed some paper stars around the room and students had to measure the angle of the star from two ends of a baseline (1 meterstick).  To find the distance to the paper stars, students drew a scaled version of the baseline (1 in = 1 meter, or 4 cm = 1 meter) on a piece of paper, then used a protractor to draw the lines of sight with the angles they measured.  Where the two lines intersect is the location of the star.   Unfortunately this is incredibly sensitive to the angles so its hard to get accurate results.  We have errors in measuring the angle and then in drawing them.  Astronomers have the same problem because the parallax is usually a very small angle because the stars are so far away and our atmosphere smears out the stars making it hard to measure.  This is why they like to put telescopes in space, above the atmosphere – it makes these types of measurement more accurate.

We ran out of time so did not get to talk about the Origin Stories from the Big History Project, will try to do that next week.  I did do the Claim Testing Snap Judgement activity from BHP – hung up  the claims (ex: the earth is flat) and asked students to put a green stickie note on the claim if they agreed with it, a pink one if they disagreed.  We discussed the different claim testers; intuition, logic, authority and evidence as we went through the different claims.  I told my students that I highly recommend the “Calling Bullshit” class from U of Washington if they are interested in learning more about claim testing. They have a series of lectures online and recommended reading.  My kids and I did this a few years ago along with the book Thank you for Arguing by Jay Heinrichs for high school English.

For the middle school class, we started with the Claim Testing exercise as well and then spent a lot of time discussing the origin stories and sharing our favorites.  I don’t think many of them filled in the chart provided by BHP but I did some of it on the white board as we discussed it as a class.  I also showed them my favorite origin story:

I gave them a shorter version of the lecture on angular diameter and units like the Astronomical Unit (AU = distance between Earth and Sun) and light years.  I ran out of time and did not do parallax with the middle school class so we’l do that next week.

This week was the first class for the high school students and I started with a slideshow on Big History and the 9 Thresholds.  We also talked about scale.  In my presentation I went through the Galactic Address activity from The Universe at Your Fingertips 2.0 DVD, which is kind of like going through the powers of 10 video. I started with a satelite view of my house, then a map of the city, the state, the country, the planet and then the solar system.  I was pleased to hear many of my students laugh at the image I used for the solar system… it was soooo bad that it showed Saturn as smaller than the Earth and Jupiter was only a bit bigger.  Instead of pointing out things that were wrong with the image, the students decided to try to find thing that were accurate… it was a short list (the planets were in the correct order).  Granted its impossible to illustrate the solar system with the size of the planets and their distances both to scale, they are just too far apart, but that image didn’t even try.  Then I showed them the image below that I found on Wikipedia and it is definitely the best one I’ve ever seen.

Not only are the planets’ sizes to scale, but it also has many of the moons, dwarf planets and asteroids which really helped me understand why Pluto got demoted.  If you look in the lower right of the image you will see a line illustrating the distances between planets.  I just love this image.  After a long discussion of this image and the scales involved, I showed them an illustration of the Milky Way Galaxy and our location in it and finally one of Hubble’s images filled with different galaxies and pointed out that our galaxy is just one of many.

The first activity we did was the Big History on a Football Field, which is a basically a big timeline…literally football field big.  They had to calculate how to represent 13.8 billion years on a timeline 100 yards long and calculate the distances between the different Big History Thresholds.  We then went outside and walked out the distances on a sidewalk.  Our timeline was a bit more than 100 yards because we used sidewalk segments as our ‘yard lines’ and they were a bit more than 1 yard apart.   The street we used wasn’t particularly straight so it was difficult to get them all in one photo.

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When we came back inside we did the Threshold Name Game.  The student holding Threshold 1, stated their name and their threshold.  Next, the student with threshold 2 had to say the name of the first student and their threshold and then their own name and threshold and so on until we reached the last threshold.  This was a great way to get everyone to learn the names of their fellow students as well as the order of the thresholds.

Lastly we did a Question of Scale, also found on the The Universe at Your Fingertips 2.0 DVD.  On one side of the page was a list of dimensions from 1 cm to 1 billion km.  The other side of the page had a long list of items, such as softball, height of Mt. Everest, the moon’s diameter,  the distance from the Sun to Saturn…. and students had to cut them out and try to put them in order from smallest to largest and figure out which ones matched which dimensions.

The middle school class met the next day and I did the same slide show for them and we spent a lot of time discussing scale with respect to the solar system, dwarf planets, and even black holes.  Since the high school class had calculated the distances for the football field timeline, I just took the students outside and asked them where they thought the thresholds would be and we put them down in the right places.  We also went over the Thresholds and played the Threshold Name Game. Then we went back inside and they did the Galactic Address activity, finding the paper with a satelite image of their house and putting all the different images together (neighborhood, city, county, state, country, world, solar system, galaxy) into a lift the flap page or a flip book.  I had hoped to do the Question of Scale activity with them as well but we ran out of time.  I’l keep it on hand for another day.  So we covered the same material, just did the activities a little different.

We’l be talking about origin stories and finishing up Unit 1 next week.

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I found a few more books to add to the Big History Reading list.  Again, I don’t expect anyone to read all of them, I just want my students to read at least 2 or 3 of them.

My son received How I Killed Pluto and Why It Had It Coming by Mike Brown a few years ago but I had never read it.  I picked it up last week and finished it in a few days.  Its a very entertaining book about the how Mike Brown and his team searched for the 10th planet and how their findings changed Pluto’s status.  There’s a lot of good science about how planets are discovered and how scientists get credit for their discoveries.

While looking for an audio book, I happened upon Elon Musk: Tesla, SpaceX and the Quest for a Fantastic Future by Ashlee Vance.  My boys and I listened to this a few years ago and it was excellent.   It would fit in nicely with the last few units of Big History.  There’s also a kid’s version, which might be good for the middle school students,  Elon Musk and the Quest for a Fantastic Future Young Readers’ Edition.

And lastly, I bought a copy of  The Total Skywatcher’s Manual: 275+ Skills and Tricks for Exploring Stars, Planets, and Beyond, produced by the Astronomical Society of the Pacific and I think it would be a great book for homeschoolers trying to do some observational astronomy.  Its got a lot of nice activities and recommendations for objects to look for in the sky.  It also has sections on binoculars and telescopes.  This book might be better than Nightwatch: A Practical Guide to Viewing the Universe for families with younger kids.

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Since quite a few high school students are going to use the Big History Project as their history or world geography as well as science (astronomy/earth science), I’ve put together a list of books that I think go along well with the course.  I haven’t read all of them yet,  but was able to find most of them in the local library and read the first chapter or two.  I don’t expect anyone to read them all but hope they will read 2 or 3 of them over the year. Most of them are non-fiction, but I threw in a few novels as well.  Most, if not all of these should also be available as audio books.

The Demon-Haunted World: Science as a Candle in the Dark by Carl Sagan.   Great discussion on critical thinking and spotting ‘faking news/science’.

The Martian by Andy Weir – Excellent novel and movie about surviving on Mars.

Nightwatch: A Practical Guide to Viewing the Universe by Terence Dickinson, Adolf Schaller. (If students get interested in star gazing this is a good book)

The Reluctant Mr. Darwin: An Intimate Portrait of Charles Darwin and the Making of His Theory of Evolution by David Quammen. My older son had to read this for his freshman college seminar and recommended it to me.  Its a very interesting read about Darwin’s life after the Beagle voyage and how he finally came to share his ideas on evolution.

Your Inner Fish: A Journey into the 3.5-Billion Year History of the Human Body by Neil Shubin.  This is also PBS series.

The Sixth Extinction: An Unnatural History by Elizabeth Kolbert.

Guns, Germs and Steel: The Fates of Human Societies by Jared Diamond.

The Invention of Nature: Alexander von Humboldt’s New World by Andrea Wulf.  I haven’t actually gotten my hands on this yet but its waiting for me at the library.  Alexander von Humboldt was an explorer, scientist, polymath and father of modern environmentalism.  There’s a graphic novel about von Humboldt by this same auther.

In the Shadow of Man by Jane Goodall.  This reads almost like an adventure novel and is her own account of studying primates in Africa.

Jurassic Park: A Novel by Michael Crichton.

The Jasons: The Secret History of Science’s Postwar Elite by Ann Finkbeiner.

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HOLLYWOOD ( and all that )

hanging out and hanging on in life and the movies (listening to great music)

Learn from Yesterday, live for today, hope for tomorrow. The important thing is not stop questioning ~Albert Einstein

graph paper diaries

because some of us need a few more lines to keep everything straight

Evan's Space

Wonders of Physics

Gas station without pumps

musings on life as a university professor

George Lakoff

George Lakoff has retired as Distinguished Professor of Cognitive Science and Linguistics at the University of California at Berkeley. He is now Director of the Center for the Neural Mind & Society (cnms.berkeley.edu).