Friday, July 23, 2010
Day 5 Astro Institute
The CLEA lab was canceled today so the day began with Shelly's lecture on 'H-R Diagram of the Stars and Stellar Evolution.' There are three ways to determine where a star is on an H-R diagram:
absolute magnitude and spectral class
apparent magnitude can be used, but then it won't be standardized
scientists use luminosity (rate of energy being given off by a star) and temperature
Some ideas pulled from Shelly's lecture:
white dwarfs are hot but small, so they appear not so bright
the sun is on the main sequence
giants are huge, they give off a lot of energy but are considered cool
super giants are huge
a main sequence star is burning hydrogen to helium
stars spend 90% of their time in the main sequence
all stars go through lifecycles
Earth was a star 13 billion years ago. It exploded and made the solar system and other stars. It was a supernova. That is known because it has elements higher than iron.
Black holes, if they are sucking in things, suck in things that are close by. It is gravity that does the sucking. The holes absorb a lot of energy. The inside of a black hole is very dense. A grain of sand could weigh as much as a solar system.
Shelly's lecture was interesting and packed with information. There was so much information that, try as I might, I couldn't keep up.
After lunch the teachers were summed up the week in a symposium prepared in advance. We were asked to speak about the things that we learned that surprised us, the tools we honestly felt we would use in our classrooms and those we didn't feel we would use at all. We also talked about the impact of the various activities from the week. Group presentations followed based on how we would use what we learned in our classrooms based on the state standards. The week closed with the distribution of certificates.
Thursday, July 22, 2010
Day 4 Astro Institute
We began our learning day with another CLEA lab, "Classification of Stellar Spectra." The idea behind this lab was to be use what we know (data) to classify what we don't know. We used known spectra of main sequence stars and compared them the spectra of unknown stars. I found the mnemonic 'Oh BE A Fine Girl, Kiss Me,' (OBAFGKM) to be very helpful in identifying the age and temperature of stars. The order goes from hot to cold, young to old. We determined the elements of the star by using absorption lines for further refinement of the classification. We also learned that it is possible to use the spectra of the star to identify it. I understood much of the concept of what we were doing but the actual doing was another story!
Following a short break Caroline gave a lecture, "Stellar Spectra in the Classroom." I have so many notes from this lecture! Spectroscopy breaks light into different wavelengths (different colors). These make up the visible spectrum of colors, red, orange, yellow, green, blue, indigo, violet (roygbiv). She spoke about where visible light fits in the electromagnetic spectrum, the progression of long wavelengths (radiowaves) to short (gamma rays) and the effect of those waves on humans. Caroline gave us a historical background beginning with the contributions of Joseph Frauenhofer, Annie Jump Cannon, and Cecilia Payne. It was nice to get this human element in the midst of so much factual information!
Caroline then gave a description of fusion and fission that will help me keep them straight. She told us fusion, which takes place in stars, takes parts and makes a whole. Specifically she said nature puts together, humans take apart.
Spectral lines form in the photosphere, an outer, cooler layer of the star. She then led us through continuum (continuous), emission (forms bright lines) and absorption (forms dark lines) spectra. Finally Caroline talked about rainbows which reflect and refract light. She also explained why the colors are always in the same order. Something I need to review on my own!
The lecture then went on to reinforce the material from the morning lab. The appearance of the spectra of a star is dependent on the temperature of the star:
Classes OBAFGKM; Color progression blue-->red; temperature progression hot-->cold.
How can you tell if a star is moving? By it's shift! A redshift star would emit a longer wavelength and would be moving away. A blue/violetshift star would be moving closer.
Wow! What a morning! Thank goodness for lunch and a chance to decompress!
In the afternoon we made spectroscopes and used them to color the patterns and identify the emission patterns we found in the spectra of a regular light bulb, flourescent light, argon, and helium. NDeRC gave us several spectrometers to take back to our classrooms.
For the final activity of the day we used Oreo cookies to model moon phases by opening the cookies and scraping off the frosting. We then put the cookies in correct postion in relation to the Earth and Sun. Remember, waxing on, waning off! This is a fun elementary lab available online.
Wednesday, July 21, 2010
Day 3 Astro Institute
Following the CLEA lab and a break Tom introduced us to solar weather. Some facts gleaned from his lecture:
- the Sun is the source for space weather
- UV from the Sun produces Earth's ozone layer
- charged particles flowing outward from the Sun form solar winds
- CMEs (coronal mass ejections) and solar flares spew fountains of high energy plasma into the solar environment
- CMEs are not as strong as solar flares
We watched a video, "NASA Warns of Super Solar Storm," about a predicted solar storm and it's effect on the Earth. We were asked to evaluate the credentials of the scientist, Michio Kaku. A good reminder for us and for our students to critically evaluate information.
The lecture continued to Earth's magnetic field:
- the magnetic field is weakening
- it flips about every 30,000 years
- next flip predicted in the next 1,000 years
- it protects us from solar flares
- auroras are photons from solar flares entering along Earth's magnetic lines
Tom then put the parts together with the conclusion that the effects of a major solar storm could disrupt communication, take down power grids... A major storm is predicted within the next few years!
A break for lunch was followed by a quick review of metric conversions. We were then split into two groups to make a scale model of the solar system. This was done with each teacher representing a planet and then measuring off the distance between the planets. The activity didn't end there! We then had to send an electromagnetic message (light) from our Sun to our dwarf planet (Pluto) and then back to the Sun demonstrating that it takes time for light to travel. It takes 9 years for the light from the star Sirius to reach the Earth!
Before we returned to the classroom we stopped at the sundial in front of Jordan Hall for a lesson on sundials.
Back inside the classroom we learned about astronomical units followed by radiometers. The vanes of the radiometers reflect (white) or absorb (black) the Sun's photons. This transfer of energy causes the vanes to spin. The stronger the light the faster the radiometer spins.
At the end of the afternoon each teacher was given a set of planet pictures and a radiometer for their classroom. Thanks NDeRC!
Tuesday, July 20, 2010
Day 2 Astro Institute
This was followed by information about types of telescopes (there are more than just optical ones), telescope placement, some of which are unusual, and the views we get from telescopes. Kate showed us a movie of the Cab Nebula which is made up of x-ray, optical, infrared and radio images. The colors are created by filters-we actually see only the optical. Kate raised the question, "Why do they look the way they do?"
Kate pointed out that the zodiac would likely be of interest to students, and that in the sidereal zodiac there is a 13th constellation, Ophiuchus, the serpent bearer. The dates for Ophiucus are November 30-December 17th. A little research on the two zodiacs indicates that the difference is the orientation of the Earth to the solar system (tropical astrology) or the Earth to the background stars (sidereal astrology). Then we each were given materials and constructed our own Galilean telescope. A Galilean telescope is a refracting telescope, using lenses not mirrors. We then took the telescopes to the roof of Jordan Hall to practice using them.
Monday, July 19, 2010
Day 1 Astro Institute for Teachers
After a break Google Earth/Sky/Moon/Mars was demonstrated by Caroline while each teacher followed along at their own computer.