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)

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)

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)

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)

May 13 - The History and Future of Black Holes

Last Friday, NSF Fellow and future NASA Einstein Fellow Dan D' Orazio gave us an engaging tour to the long history of the most exciting and mysterious astrophysical objects. Black holes are objects with very strong gravitational pull, that nothing can escape from them. John Michell was the first to suggest the idea of such a "dark star", in the late 18th century, although this idea went almost unnoticed at the time.

The story continues in the beginning of the 20th century, when Albert Einstein conceived the general theory of relativity, a revolutionary theory to describe gravity. Dan described the early advances of the theory, including the first solution of Einstein's equations for a spherical non-spinning black hole by Karl Schwarzschild, and the skepticism that followed, mainly driven by the famous British astronomer Sir Arthur Eddington. Dan later discussed General Relativity's golden era (the 60s), with several significant contributions by many great physicists, among which the solution of Einstein's equations for a spinning black hole by Roy Kerr and the suggestion that under specific circumstances black hole can emit radiation, the so-called Hawking radiation. Dan also mentioned the history of the term black hole, which was coined in one of NASA's centers, above Tom's Restaurant in our own neighborhood.

By the early 70s, astronomers acquired the first observational evidence for astrophysical black holes with X-ray telescopes. For instance, the X-ray binary Cygnus X-1, in the constellation of Cygnus hosts one of the most nearby black holes. Earlier in the 1950s, astronomers had discovered radio galaxies with very extended jets, which later realized that can only be powered by supermassive black holes, i.e. black holes with a million to a billion times the mass of the sun. A supermassive black hole resides in the center of our galaxy as well and was discovered by detailed observations of the motion of stars in the close vicinity of the galactic center. Dan finished this exciting journey of discovery by describing the most recent breakthroughs, such as the numerical solutions of Einstein's equations 10 years ago and the first direct detection of gravitational waves of two merging black holes by Laser Interferometer Gravitational Observatory (LIGO), just 3 months ago. Even though, so far we had strong evidence for the existence of black holes, the LIGO event serves as the first direct confirmation of black holes.

Unfortunately, due to bad weather stargazing was not possible. However, the audience had a chance to join tours of the Rutherfurd Observatory on the roof of Pupin, lead by graduate students Steven Mohammed and Steph Douglas. Additionally, undergraduate student Richard Netherlander, guided the audience to the majesty of the cosmos through the projections of 3D movies, while, at the lecture hall, Andrew Emerick presented a mini-lecture on reionization and showed a mesmerizing movie about the end of Dark Ages.

-- Maria Charisi (graduate student)

Apr 29 - Explosive Origins of Our Elements

Every single thing we encounter on Earth exists because, at one point, its atoms were processed through stars. This week Sarah Pearson took us through a tour of the origin of the elements, from hydrogen and helium, through every element in our bodies and the world around us. The real stars of tonight's lecture were supernovae, the beautiful explosions that both produce and distribute elements throughout the universe.

Shortly after the Big Bang, the universe consisted almost entirely of hydrogen and helium. At this point, we had a long way to go before enough elements were produced to give rise to the rich chemistry that governs life here on Earth. As Sarah explained, within the first stars, and in every star since then, nuclear fusion smashed together hydrogen and helium to form increasingly heavier, and more complicated elements. However, these elements would still be trapped within the cores of stars if it not were for a weird quirk of physics. As Sarah showed, once iron is produced within stars, they enters its death throws; quickly collapsing then suddenly exploding with tremendous energy....

Sarah showed images observations of supernova remnants, the hot gas left over after a supernova explosion. This gas expands and mixes with its surroundings, carrying elements produced inside the star with it. Over time, after many explosions, these elements mix throughout a galaxy, eventually ending up inside new stars where the cycle continues.

After the talk, we discussed recent updates to the upcoming James Webb Space Telescope (JWST). Lauren Corlies gave an overview of the instrumentation of the JWST, the replacement to the Hubble Space Telescope. Andrew Emerick talked about the science goals of this upcoming mission, from observing exoplanets in the Milky Way to the first stars and galaxies formed near the beginning of the Universe.

-- Andrew Emerick (graduate student)

Apr 1 - New Horizons

This week Lauren Corlies, a sixth year graduate student here at Columbia, took us on a journey to the far reaches of the Solar System with the fastest spacecraft every built.

New Horizons is the fruit of a project spanning decades and left Earth nearly 10 years ago. Launched with the principle goal of a Pluto flyby, Lauren chronicled its path through the inner solar system and the asteroid belt, its close encounter with asteroid 132524 APL, and the gravity assist from Jupiter which enhanced its speed and gave it the energy needed to reach Pluto.

After she described the various scientific instruments onboard New Horizons (which include high-resolution optical, ultraviolet and infrared cameras and spectrometers, magnetic field sensors, particles counters and radio science experiments), Lauren told us about some of the amazing science results from the mission. To name just a few, the New Horizons team has found that Pluto’s atmosphere is much denser than anticipated and contains stratified haze layers of unknown origin; that the bright and heart-shaped “Sputnik Planum” region is a vast plain of nitrogen ice with the consistency of toothpaste where water-ice mountains, kilometers in size, floating like icebergs; and that several of Pluto’s five satellites show signs of being the lumpy remnants from collisions of smaller bodies.

Lauren highly recommended checking out the New Horizons website to see more fascinating pictures from the flyby and the spacecraft’s current status as it exits the solar system.

-- David Hendel (graduate student)

Mar 4 - The Gas that Fills Invisible Space

How do show something that's invisible? How can we view, model and understand those parts of our universe which are beyond the scope of our senses? How can we use a grad's students unwavering desire for pizza to explain our galaxies inexorable gas guzzling?

Yong Zheng took us on a journey from waking up and rifling through the fridge to building a massive galaxy by throwing swirling disks of stars and gas together. With delightful hand drawn cartoons and a many laughs she showed us that there's much more to the Milky Way than meets the eye, and by examining electromagnetic waves way out of the spectrum our eyes can see we can infer the private life of gas streaming in and out of galaxies. Culminating in beautiful films from the Illustris simulation she invited us to consider what interesting and varied information may be hidden just out of sight.

Afterwards Stephanie Douglas, gave a short talk on how clusters of stars passing near the milky way are ripped apart into long thin streams that we see cutting across the night's sky. Our 3D wall was showing off everything beautiful movies on topics ranging from the surface of our sun to collisions between galaxies. Patchy clouds and technical issues made observing tricky, but those who persevered were able to peer at the Orion Nebula and Jupiter using portable telescopes on campus. The roof was also open for tours but sadly conditions made it impossible to view the sky through it.  

-- Zephyr Penoyre (graduate student)

Feb 19 - Ripples in Spacetime

A record crowd packed into the lecture hall tonight to hear Jillian Bellovary talk about gravitational waves and how to detect them. Jillian's research focuses on supercomputer simulations of supermassive black hole binaries, but her presentation focused on much less massive binaries like those whose merger was detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in September. Gravitational waves are very small distortions in spacetime caused when massive objects are accelerated to high speeds. The distortions measured by LIGO were smaller than the radius of a proton -- and those were caused by two ~30 solar mass black holes merging together. Jillian showed simulations of how these ripples in spacetime are created by the two merging black holes.

Jillian also described how LIGO was able to detect these tiny distortions. LIGO is an interferometer, meaning it measures how light waves interfere with each other (either adding together or canceling each other out) after they travel a very long distance in two perpendicular directions. How the interference pattern changes with time tells LIGO scientists how the distance is changing in each direction. If the "arms" of the interferometer lengthen and compress in a particular pattern, then they know they've detected a gravitational wave!

The sky was cloudy, but graduate students Adrian Price-Whelan and Lauren Corlies, along with undergraduates Amanda Quirk and Cierra Coughlin, showed off the Rutherfurd Observatory. Meanwhile, undergraduates Richard Nederlander and Tze Goh screened short films on the 3D Wall. In the lecture hall, volunteers Stephanie Douglas, Maria Charisi, and Danielle Rowland played videos from PhD comics and from members of the LIGO team at CalTech, and answered audience questions about gravitational waves.

--Stephanie Douglas (graduate student)

Jan 29 - BLAST!

Our first event of the year didn't exactly go as planned as our scheduled screening of BLAST! was plagued by technical difficulties. On the other hand, a thoroughly overcast day miraculous cleared up right as our stargazing began so what might have otherwise been a disappointing night turned into one of the better observing sessions we've had this winter! Led by graduate student Yong Zheng, astronomers on the roof had telescopes pointed at the Orion Nebula, Jupiter and the Galilean moons, and the Pleiades star cluster. On the indoor side, undergraduate Gladys Velez-Caicedo, ran our 3D Wall for a packed house.

For those interested in seeing what actually happened with the BLAST experiment, we hope you'll give us another chance and come see us over the summer for our Film & Stargazing series. We will reschedule our screening of the film then (and will bring every back-up system ever invented).

Thanks to everyone who came out for their incredible patience throughout the evening.

-- Summer (Director of Outreach)