Mar 3 - Las Atmósferas Estelares

(This was our 3rd Annual Spanish-Language Lecture)

Turns out the Sun has an atmosphere, albeit very different from Earth’s. Alejandro Núñez, a graduate student at Columbia University, unveiled what is known about this gaseous envelope, layer by layer. He further described how a flotilla of space probes is helping scientists clarify some remaining mysteries by continuously gathering data from all angles and wavelengths. The most vexing of these unsolved questions is how the corona -the outer layer of the Sun’s atmosphere- can be hundreds of times hotter than the photosphere -its visible surface-, reaching temperatures in excess of a million degrees Celsius. While a detailed description of the heating mechanism still needs to be developed, it seems to be linked to the complex interaction between the Sun’s magnetic field and its atmospheric plasma.

Turns out the Sun is also a star. Thus, we can extrapolate what we learn about the Sun to other stars. As Alejandro explained, we need to do so with caution, for different stars can have diverse levels of magnetic activity. He illustrated this with a discussion on how the red dwarf at the core of the recently discovered multiple planetary system Trappist-1 seems to be much more active than our Sun, and the consequences that this could have for the habitability of the planets orbiting it.

This was the Spanish public lecture of this season, and the audience had the opportunity to stargaze at the Rutherford observatory on Pupin Laboratories’ roof after the talk. The night was cold and partly cloudy, but we managed to get a glimpse of some objects like the Moon and Mizar through some clearings.

-- Jose Zorilla (graduate student) 

October 25: The Sounds of the Stars

In the lecture on Friday, October 25th, the magic of sound was unveiled by Jeff Oishi, a research scientist in AMNH, who vividly showed that sound waves could be decomposed into simple sinusoidal plane waves. With the help of specific frequency-analyzing software, the differences among various types of sounds, such as whistles, noises, singing were visualized based on their amplitudes and frequencies (pitch). Jeff also introduced an application of sound waves in asteroseismology, by which means the internal structures of stars wound be known since sound waves wound present different oscillation modes when propagating through different depths. 

After the lecture, discussions on topics such as interpretations of sound waves’ propagation and the earth tides took place between the speaker and the audience. In addition, the weather was so amazingly good that a lot of visitors went up to the roof to enjoy the observations of Altair, Albireo, Vega, and the Owl Cluster. 

Volunteers on Friday night included graduate students Jingjing Chen in the lecture hall and Susan Clark, Steph Douglas, Ron Tso, Tze Gho and David Jaimes on the roof.

— Yong Zheng (graduate student)

July 16, 2011: Family Astro: THE SUN

Luckily the clouds stayed away for the Family Astro event on July 16th because the topic was "The Sun". About 10 kids and 10 parents attended the event. Our first activity was tracing our shadow with chalk. We did this once at the beginning of the event, and once two hours later at the end in order to see how the position changed due to the apparent movement of the Sun through the sky. We then made scale models of the Sun and Earth out of paper to show the extreme size difference and large distance between the Sun and the Earth. Next we made our own "UV detector" bracelets out of UV color changing beads (a.k.a. Solar Energy Beads) and tested them outside and in a plastic bag covered in sunscreen. Participants then wrapped a map of the Earth around themselves and rotated like the Earth does, and we shone a lamp on them to simulate the Sun's light. This illustrated the cause of night and day and showed how it can be daytime on one side of the Earth and nighttime on the other. Finally, Graduate Student Duane Lee gave the kids and their parents a peek through a special solar telescope, and gave a tour of the telescope dome on the roof. Thanks to the volunteers for making this event a success!

March 28: A visit to PS 282 in Park Slope, Brooklyn

Today, March 28, 2011, in the morning three Columbia University Astronomy Department graduate students and one undergraduate visited PS 282 in Brooklyn with two telescopes in tow. As the moon was a few days past third-quarter phase, it was possible to see both the sun and the moon! 120 first graders braved the cold and waited patiently for their turn to take a look at each of these celestial objects. Many of them had never looked through a telescope before and were very excited that they could see dark and light spots and even a few craters on the moon's surface as well as sunspots on the Sun. At the end of the visit, each class was presented with 3D images of the Sun, posters, and some CD-ROMs for distribution among the students.

Many thanks to the volunteers who made the trek out to another borough to help raise astronomy awareness.