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Big History Science 09 – Our Sun

High School students were to read Foundations of Astronomy Chapter 8: The Sun and watch Crash Course Astronomy #10 The Sun.

I downloaded a powerpoint file on The Anatomy of the Sun by Swinbourne University and changed it a bit for my class.  If you click on the link above, it will download the original powerpoint file.  I also added some slides from the Night Sky Network’s  Space Weather Powerpoint .  The Night Sky Network also has a script you can read along with the slideshow.  There are activities that you can download as well, including some activity cards that you can print at home.  I have some of the activities/toys mentioned on this website since I’m a member of our local astronomy club and help with educational outreach.  If you have a local astronomy club, reach out and see if they will do some educational activities for your group.

I found Identifying Elements in the Sun using Spectral Lines on the Columbia University website.  Students are given a section of spectra (see image below)  with various lines marked with letters.  The lines indicated by capital letters are already identified in the handout, but students have to figure out which elements are causing the lines labeled with lower case letters by looking up their wavelength in a provided table.image

IMG_8009The second activity is yet another one I found on the Universe at Your Fingertips 2.0 DVD, Activity G3 The Sun’s Period of Rotation.  It can also be found here.  I had to print out a grid of latitude and longitude lines on transparencies that students could place on top of photos of the sun and record the position of sunspots.  Unfortunately, we’re in the minimum of the sunspot
cycle so there weren’t any current sunspots for us to observe.  The activity comes with photos of sunspots over a couple of days that student can use.  By measuring the motion of the sunspots over a few days they can calculate the rotational period of the sun.  This is a really nice activity because they aren’t not just learning about sunspots, but also learning how to identify a position on a sphere with latitude and longitude.

IMG_8011Lastly, I had a variety of magnets, including a model of the sun with magnetic sunspots (one of the astronomy club’s outreach items), that students could investigate with iron filings.  I had iron filings in a ziplock bag and clear plastic cases with iron filings that came with old science kits.IMG_8034

I also showed the students an image of the sun today from spaceweather.com and watched a movie of a corona mass ejection (CME) that took place yesterday (not aimed at earth).

IMG_8035The middle school class did the same activities.

While searching the internet for activities I found the Nebraska Astronomy Applet Project with a lot of nice interactives. If you click on the image below it will take you to the blackbody  interactive.

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Big History Science 08 – Inverse Square Law & Star Clusters

High School students were to read Chapter 12 Stellar Evolution in Foundations of Astronomy and look at articles/videos in 3.2 & 3.3 in Big History Project.  There’s a long list of Crash Course Astronomy videos that were also recommended: 28-31, 34 and 35. We started class with the Claim Testing – Intuition 3.2 from Big History Project.   I put the claims out on a table and students put sticky notes on each claim, pink for disagree, green for agree and blue for need more information.  There are a few claims in this batch where most people will not know whether its true or not without doing some research since they involved very specific knowledge.

IMG_7890There were two different labs this week.  The first lab, The Inverse Square Law of Light, is one I found on the Universe at Your Fingertips DVD, but there is a slightly different version found on this NASA website.  In a darkroom you tape a piece of graph paper on one side of a box, the opposite of the box is removed so you can move the flashlight to larger distances.  The flashlight bulb (single bulb like mini maglite) should be secured 10cm from another piece of cardboard with a 1cm square hole.  As you can see in the photo above, a square of light illuminates the graph paper, as the flashlight is moved further away the number of squares lit up on the graph paper will increase.  Students measure the number of square illuminated as a function of distance between the light and the graph paper.  The lab handout explains how to convert the number of squares into a relative brightness (basically one over the area) and students plotted the relative brightness as a function of distance.  Some of the students used graphing calculators or the graphical analysis app to do a best fit of their data.

Screen Shot 2019-10-08 at 2.41.11 PM

The photo above shows that the brightness depends on 1 over the distance squared.  I reminded students that the force of gravity between two objects also depends on the inverse squared of the distance.   We had two set ups like the one above and one set up IMG_7887using a PocketLab Air which has a light sensor on it and connects to an iPhone/iPad via bluetooth and their PocketLab app.  The students using the PocketLab Air were able to measure the light intensity directly as a function of a distance by moving a flashlight along a ruler and recording the light intensity at each position.  The data also shows a 1 over distance squared relationship.

IMG_6066
Intensity (Lux) measured at different distances (cm) between a flashlight and PocketLab Air.

The second lab, How Old Are the Jewels of the Night? Measuring the Ages of Stars, is another lab I found on the Universe at Your Fingertips DVD.  It can also be found  as Jewels of the Night on this NOAO website.  Students were given a color glossy photo of IMG_7885the Jewelbox cluster and a Star gauge that helped them identify the brightness (size on photo) and spectral type (color) of each star in the cluster.  The photos were laminated so students could draw on them with whiteboard markers.  They started by marking a square, approximately 4 cm on a side for their sample area.  One student would call out the size and color of the stars while another student recorded it on the worksheet (H-R diagram).  After recording the information for all the stars in their sample area they compared their diagram to diagrams for young, medium and old clusters and were able to conclude the age of the cluster. All the stars in a star cluster are the same age but because gas can fragment and clump in different sizes, they contain a range of sizes and star types.  If the cluster is old then there won’t be any large O or A stars since they have a short life span.  If the cluster still has large bright stars than its probably a younger cluster.   A few students also looked at a sample of the field stars – stars along the edge of the photo that are probably not part of the cluster for comparison.

The middle school class also did the Claim Testing, Jewelbox Star Cluster activity and measured the light intensity as a function of distance with the PocketLab Air.  We also discussed Cosmic Microwave Background radiation and exoplanets a bit since they were both in the news yesterday with the Nobel Prize in Physics being announced and watched the following video in class:

Big History Science 07 – Stars & Atoms

High school students were to read Chapter 7 Atoms & Spectra in Foundations of Astronomy, watch videos in Big History Project 3.1 and Crash Course Astronomy #24 Light.

In class I gave a slideshow on atoms, energy levels and spectroscopy.  We also watched the following videos in class:

I spent most of the class explaining the energy levels of atoms and and how they are related to the light given off or absorbed by the atoms.  By looking at the spectra of star light we can tell which elements are present near the surface of the star.   We also discussed how objects changed color with temperature – think of the wire in your toaster that gets red, than orange as it gets hotter.   Wein’s Law states that the wavelength (color) of maximum intensity emitted from an object depends on 1 over the temperature.  The higher the temperature, the lower the peak wavelength of light.  In the image below, the rainbow region is showing visible light  (visible to us anyway) and the curves are showing the distribution of radiation for stars of 3 different temperatures.  Cooler stars will appear more red but also emit more infrared light (longer wavelengths), while hotter stars will appear bluish but the wavelength may peak in even shorter wavelengths (ultraviolet).

star_colors

From looking at the light we can figure out the temperature of the star, elements that are present and if the spectral lines are redshifted we can determine the velocity of the star.

imageFor the lab activity, I did the colored flame demo, which most of the students had seen before, but colored fire is always fun.  I soaked wooden skewers in water and then dip one in a salt – lithium chloride, potassium chloride, cupric chloride, etc and then hold it over a small butane burner.  If you buy this spectroscope analysis kit it comes with simple spectrometers that help you see the emission lines.  Cupric chloride does not come in the kit, I bought that separately so we would have a blue/green flame to look at, see photo above.

The high school students put together the Star Life Cycle that the middle school students did last week and put hashtags on the Narrative Threshold Graphic (BHP) for threshold 2 and 3.  We also did the Big History Project 3.1 Causation – Star Formation 2 where the students had to fill in the rest of the causal map for star formation/life cycle. IMG_7607 Lastly, we did the Star Class activity from BHP 3.2, where groups of students were given a set of stars labeled with their  names, temperature, and luminosity.  The stars were different sizes and colors representing approximately their color and relative sizes.  The worksheet has the students sort the stars by color, size, temperature and luminosity and record their observations.  In the photo above you might think they were sorting them by color, but they are actually sorted by temperatures.  This really drives home the point that a star’s color is related to its temperature with blue stars being the hottest and red stars the coolest.

The middle school class did the same activities as the high school class.  Next week we move on to BHP 3.3 and 3.4.

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Big History Science 06 – Formation of Stars

High school students were to read Foundations of Astronomy section 10-3 Gas-Star-Gas cycle and Ch 11 Star structure & formation and/or watch the videos for Big History Project Unit 3.0 and the following Crash Course Astronomy videos.

As students arrived for class I had them fill out a moon journal page, starting with today’s date and then stepping outside to view the moon and sketch what they saw.  I also had my telescope set up so students could take a closer look.  I told the students to keep the observation log on their fridge or somewhere they will see it and remember to step out and observe the moon each day.IMG_7478.jpeg

IMG_7483
Photo of the moon taken after class on Sept 24, 2019 with my iPhone mounted on my Skymax 102 telescope.  I used the Moon Phase Photo Maps app on my iPad to identify a few craters.

Once everyone had their first moon observation, I gave a slideshow on star formation, different type of nebula and the life cycle of stars.  You can find a slideshow on the Lives of Stars at the Night Sky Network.  This site has a ton of fantastic resources for astronomy, just use the search window to find activities, slideshows, posters, etc for your topic.

SNFusion1
Nuclear Fusion in Stars Activity

After the slideshow, we did the Nuclear Fusion in Stars activity, also from the Night Sky Network.  In this activity we had a bowl of mini-marshmallows represents protons (Hydrogen nuclei) and a bowl of short pasta representing gamma ray photons.  I asked each student to grab two protons (marshmallows) and asked them what they knew about protons – they have positive charge.  So do two protons want to be close to each other? No!  They repel each other.  For two protons to undergo nuclear fusion they must be traveling very fast and collide just right, and when they do they release energy in the form of gamma radiation. At this point everyone squishes their two marshmallows together and grabs a piece of pasta to represent the gamma photon that was released.  We’ve now made a helium atom (2 protons) and need to make two more.  One you have 3 helium atoms you squish two of them together, producing another gamma photon and then the last helium nucleus fuses with the 4 protons so that you now have 6 protons in your nucleus, which means you made carbon.  I mentioned that we didn’t make lithium (3 protons) because its not stable and falls apart almost immediately, which is why stars are mostly H and He.   Protons do not undergo nuclear fusion with every collision, most collisions just send them flying off in different directions. But at the high temperatures and densities inside a star,  the number of collisions is very high, so even though only a small percentage of the collisions end in fusion, its still a ridicuously high number of events per second (10 38 )!

The second activity, a Star Scale Model,  is one I found on Astronomy Professor Kate IMG_7468Follette’s website.  Students are given a table of 25 of the closest star systems to our sun, with the type of star, its distance and position (right ascension and declination).  A second table has the ballon specs for each type of star,  for example if the star is an M type then they need to blow up a red balloon so it has a radius of 2.5 inches.   I didn’t have enough red balloons for all the M stars so we substituted circles of red paper of the appropriate size.  This entire activity could be down with paper circles instead of balloons.  We divided up the list of stars so each group of students made 6 to 7 stars and then came the hard part…. figuring out where to put them.

Ra_and_dec_on_celestial_sphere
Wikipedia: Right ascension (blue) and declination (green) as seen from outside the celestial sphere 

 The farthest stars are 12 light years away. We used 1ft = 2 ly, so all the stars should be within 6 feet of our sun (a star shaped toy in the middle of the room).  To figure out right ascension (R.A.) for each star, I placed signs at four points around the room 0/24 hours, 6 hr, 12 hr, 18hr.  If a star is 4 ly from our sun with R.A. 14:29 hr then the students would place the star 2 feet from the ‘sun’ about half way between 12 and 18 hr.   We didn’t worry about declination since we didn’t have an easy way to suspend the stars (ballons) in the air.  The activity sheet has a number of questions that we answered as a group and everybody made a histogram of the star type distribution.

Lastly we did the Causation – Star Formation Part 1 activity from the Big History Project Unit 3.0.  The activity has a causal map, showing the causes and effects for star formation.  The map is complete with the exception of one circle, the trigger for star formation, which students filled in.

IMG_7493The middle school class also started with the moon observation page, the slideshow on star formation and nuclear fusion with mini-marshmallows.  But instead of doing the entire Star model from scratch, I handed them balloons already labeled with one of the star names and they had to look it up on the table and figure out where it would go in our model.   I also had them put together a Life Cycle of a Star from an interactive notebook, Astronomy & Space Science by Nitty Gritty Science that I bought on TeachersPayTeachers.com.  The yellow sheet in the photo above has a one page description of the life cyce of a star that goes with the diagram they made.

 

 

Big History Science 05 – Fieldtrip & Gravity

CWSF0379Over the weekend, my students and I took a private tour of the Lick Observatory on CWSF0309.jpgMount Hamilton.  We got to see a couple different telescopes, hear about the research they’re involved in, and learned about the life of James Lick.  Unfortunately, clouds were rolling in and the humidity was too high to use the big telescope for viewing (don’t want condensation on the optics).   But I was able to set up  my  telescope (outside the dome in the photo above) so everyone got to see Saturn and Jupiter before we had to head down the mountain.   It was actually pretty dark when the above photo was taken, that is the Milky Way appearing vertically by the dome and an airplane trail crossing over the dome.  I highly recommend taking a fieldtrip to a local observatory if you have one in your area.

Instead of lecturing on the force of gravity this week, I had the high school students use a physics simulator at the Physics Classroom website to figure out for themselves how the force of gravity depends on the distance between objects and the mass of the objects. Screen Shot 2019-09-17 at 1.08.05 PM They have an activity sheet you can download that steps you through this activity.  By moving the sliders you can change the mass of the moon and the planet, or you can move the moon closer or farther from the planet. This interactive works on smart phones and tablets as well as laptops.

Students set the masses and then recorded the Force at different distances.  The handout does not require a graph, but I had them make a graph of their data.  One student used a graphing calculator to do a best fit to his data and found that the force depends on 1 over the distance squared.Screen Shot 2019-09-17 at 12.51.05 PM

Students then kept the distance fixed and changed one of the masses and found that the force of gravity depends linearly on mass.IMG_7398

I also set up a demo that demonstrates how massive objects curve space-time by stretching a large piece of spandex-like fabric over a hula-hoop and then balancing it on chairs to keep it level.  When a large marble is place in the center the fabric stretches and curves the fabric (space-time)IMG_7408.jpeg

The larger the mass, the more the fabric is curved.  Students took turns making smaller marbles orbit the large marble.  We also increased the ‘mass’ of the ‘star’ in the middle by pulling down on it from below.   I also talked about LIGO and how they’re measuring the vibrations on the fabric of space-time, which are gravitational waves.  Here are videos on the subject.

Students were to read Chapter 5 Gravity in Foundation of Astronomy and watch the following Crash Course Astronomy this week.

We also did the How Do We Know What the Milky Way Looks Like? Activity from the Big History Project Unit 2 under Other Material.  Since we can leave the Milky Way galaxy, the images that we see of it are not photographs but artists renderings based on what we can infer from our observations.  Students were asked to pretend that they had never seen the outside of the building we were in and to write down a description of the house using only information they could gather from inside.  They also had to write down what they could tell about about an ancient group of people from just a few photos of archeaological evidence.

The middle school class did the same activity sheet on gravity using the website but I started the class with a presentation on Newton’s Laws, the difference between speed and velocity, acceleration, forces and gravity.  I skipped the presentation with the high school class since many of them had taken physics with me already.  I did not require the middle school students to graph their data, but sketched the graphs on the white board.  We also did the BHP How Do We Know What the Milky Way Looks Like? activity and played with the fabric of space-time.

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