Friday, March 17, 2017

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) 

Tuesday, February 7, 2017

Feb 3 - Earth in Human Hands

On Friday night, author and astrobiologist David Grinspoon shared his new book, "Earth in Human Hands", with us. He claimed we are entering a new era on earth called the Anthropocene - the age of humanity. For better or worse, we are reshaping our planet, and we have the capability to be aware of and intentional about the changes we enact. He also told us about another species living 2.5 billion years ago that caused catastrophic climate change: cyanobacteria learned to generate O2 through photosynthesis, which changed the composition of atmosphere and that destroyed many other bacteria that thrived on the previously methane-rich atmosphere. He also made the distinction between inadvertent vs intentional changes in climate. For example, when we began driving cars on a wide scale, we didn't initially understand the environmental impact that would have. However, in the 70s, the world responding to ozone depletion by banning chlorofluorocarbons (CFCs), intentionally working to recover that protective layer between the Sun and us. Finally, Dr Grinspoon believes we can positively affect future climate, even beyond reversing the effects of humans on the climate - we could avert a future ice age, for example, since we know those happen periodically even when the Earth is left to its own devices. 

After the lecture, Dr Grinspoon signed copies of his book, and then undergraduate Erin took the audience on a brief tour of the other planets in our solar system. Upstairs, undergraduates Richard and Cierra showed movies on the 3D wall, and graduate students Aleksey and Daniel led roof tours. 

-- Stephanie Douglas (graduate student)

Wednesday, January 25, 2017

Dec 16 - How to Hold a Dead Star in Your Hand

Our speaker, Kimberly Arcand, didn't come from an astronomy background. She began her science career as a biologist studying deer ticks, then moved into computer science before joining the Chandra X-ray Center (CXC), where she is now the visualization lead. Her job is to take the data and turn it into interesting and useful pictures. The data is beamed down from the telescope to NASA and then sent to the CXC as a lot of 1s and 0s. This is cleaned and assembled into black and white images; part of Kimberly's job is to determine how best to color these images to make them informative. Often, Chandra images are colored by the X-ray energy range or the dominant chemical/element.

Color has meaning. Kimberly spends part of her time studying responses to different color schemes, and choosing the right color scheme based on the audience for an image. Scientists think of blue as hottest, but culturally most people associate red with heat. Because Chandra images are important for outreach to the general public, her team picked red for the hottest parts of an image, rather than the blue that the scientists wanted.

Kimberly also told us about her work on visualizing the Cassiopeia A supernova remnant. Chandra (along with the Spitzer infrared telescope and Hubble Space Telescope) has observed this expanding shell of gas over many years, and you can actually see the gas moving outward in images taken several years apart. There is enough data that her team could use software borrowed from brain imaging to make the first 3D model of a dead star. She showed us a movie where we flew through the Cas A remnant. They also made a 3D printed model of the remnant - you can download the free file here if you want to hold your own dead star in your hand.

After the lecture, undergraduate Richard took us on a tour through all the scales of our universe, undergraduate Briley showed short astronomy movies on the 13th floor, and graduate students Alex and Aleksey led tours of the roof. Myself and graduate student Moiya also helped facilitate in the lecture hall.

-- Stephanie Douglas (graduate student)

Monday, November 14, 2016

Nov 4 - The Cosmic Origins of the Chemicals of Life

We start, as perhaps all good talks should, with Genesis. Daniel Wolf Savin took us through the first three days of creation, from the light of our universes first stars to the formation of water, and maybe even life, on planets like our own. In the lab his team has recreated the chemical conditions of the first stars and used it to infer some of the evolution and distribution of the chemicals that form the building blocks of life. On the way he also gave us pearls of wisdom such as the best way to ensure a healthy supply of Belgian chocolate in your laboratory, and jokes that even he admitted were "good science but bad comedy".

After his stellar ("good science") talk we also heard from astronomy graduate student Moiya McTier, about how space affects all of our everyday lives. Meanwhile up on the roof we had clear skies, with Stephen Mohammed, Jorge Cortés, Danielle Rowland, and Emily Sandford guiding our telescopes to the Moon, Mars and a proliferation of double star systems. And finally but fluently we had Erin Flowers explaining the wonders of the universe in all your favourite dimensions on the 3D wall.

-- Zephyr Penoyre (graduate student)

Tuesday, November 1, 2016

Oct 21 - Surviving the Misinformation Age

In the past, information was scarce, but generally high quality. Conversely, in the last 10-15 years, the amount of information produced by humanity has skyrocketed while simultaneously being made accessible to nearly every human being on the planet. Tonight, Professor David Helfand discussed the challenges that this firehose of data presents to society. 

The internet is full of mis-information that is easily accessible and appears vetted. Prof. Helfand told us about the tendency for people to cherry-pick data, i.e. selecting only evidence that fits their pre-determined argument, rather than assessing or even accepting all the available evidence. He also critiqued the "echo chamber" that can be created in online spaces. He urged the audience to be skeptical and listen to a variety of sources, and to search out the evidence behind claims they read or hear. Prof. Helfand's talk was based on his new book, "A Survival Guide to the Misinformation Age."

Despite the clouds, graduate student Aleksey Generozov and a team of volunteers showed off the big dome and telescope. On the 13th floor, undergraduate student Richard presented movies on our 3D wall. 

-- Stephanie Douglas (graduate student)

Friday, October 14, 2016

Oct 7 - Black Hole Duet

"We did it!" says the soundbite, and while the screen fills with fireworks the lecture hall fills with applause. This is the culmination of an almost century long journey between Einstein's first postulates of general relativity to our first detection of gravitational waves last September.

Maria Charisi, graduate student and guide through the fabric of space-time, took us through the last moments of the life of a binary black hole. The LIGO project has taken almost 50 years, from the first genesis of the theory to the eureka moment of detection, to find gravitational waves. By measuring the minuscule variations in space-time, a fraction of the width of the nucleus of an atom, we can observe the ripples from distant violent collisions between black holes. Since the first detection we've found 2.9 merger events (the last one we're only 90% certain of, the other results ring clearer than a bell) and when we restart it with improvements in a few years we might find as many as 50 more.

After the main lecture Jordan Borgman took us to Tatooine, Luke Skywalker's home planet to talk about how the planets of Star Wars match up with the exoplanets we're discovering in our galaxy. Meanwhile Erin Flowers guided us through 3D visualizations of the universe on all scales.

Up on the roof, Alex Teachey orchestrated a beautiful (mostly) clear night of viewing through the telescopes. In the able hands of Richard Nederlander, Aleksey Generozov and Rose Gibson we had telescopes pointing at Mars, the Moon, and the Double Cluster.

-- Zephyr Penoyre (graduate student)

Tuesday, June 14, 2016

May 20 - La Escalera de Distancias Cósmicas

Our last public outreach night of the spring semester was a special version, as the whole event was conducted in Spanish. Although the event was targeted to the Spanish-speaking community of New York, the audience was mixed, as some non-Spanish speaking attendees chose to skip the talk and head directly to the roof top to observe the sky. We were lucky enough that night to have bright Jupiter and the Moon easily accessible from our telescopes.

José Zorrilla, a graduate student in the Astronomy Department at Columbia University, gave a talk titled “La Escalera de Distancias Cósmicas” (“The Cosmic Distances Ladder”), in which he explained some of the ideas and methods used in astronomy to determine distances across the universe. He began by explaining the concept of trigonometric parallax and how astronomers use it to measure the distance to nearby stars. He then talked about astronomical objects known as standard candles, such as supernovae and some types of variable stars. These, he explained, can be used to measure much greater distances, to galaxies in the vicinity of the Milky Way and beyond. Lastly, José talked about redshift as a way to measure distances to the most faraway galaxies in the universe. To put it all together, José explained how the different methods rely upon others to determine distances to the most remote objects we know in the universe, hence the term “ladder”. He also pointed out that the discovery of new distance measuring methods has led the revolution in our understanding of the universe and its true extent.

-- Alejandro Núñez (graduate student)