March 15: Cosmic Candles

Last week, Ashley Pagnotta, a post-doc at the American Museum of Natural History, gave a talk entitled, "Supernovae: Cosmic Candles of the Universe." Ashely's research focuses on stellar explosions known as supernovae which occur toward the end of a star's life. Different phenomena give rise to different types of supernovae and by understanding the nature of these explosions, astronomers can better constrain the parameters that help us describe the behavior of our Universe. 

It was less than a hundred years ago that astronomers even discovered that the Universe wasn't static, i.e., "standing still". Using the doppler effect to measure the speed at which galaxies were moving away from Earth and cepheid variable stars to measure distance, Edwin Hubble made a plot of of these two variables and discovered that the farther a galaxy was from Earth, the faster it was moving a way from us. Today, we call this plot the Hubble Diagram in his honor and continue to update it as we make better and better measurements. You can make you own Hubble Diagram using data from the Sloan Digital Sky Survey here. 

While Hubble's work showed that Universe is expanding, it said nothing about the future of this expansion. To investigate this, two teams of astronomers proposed using Type 1a supernovae to probe the Universe out to greater distances, and therefore farther back in time. They used Type 1a supernovae instead of cepheid variables as these supernovae have a characteristic explosion that allows astronomers to use them as a standard candle of sorts; astronomers know how bright they are at a given distance so they can observe them at various distances and extrapolate their true distance based on their observed brightness. Both teams ended up discovering that the expansion of the Universe was *accelerating*, giving rise to the theory of dark energy, and as a result we awarded the Nobel Prize for Physics in 2011. 

Ashely went on to explain how studying how Type 1a supernovae form in more detail can help astronomers minimize errors associated with their distance measurements and thereby improve our understanding of dark energy. You can view the slides from Ashely's talk here. 

Unfortunately, the skies were cloudy again so after the lecture, the 120+ audience members toured the roof with the help of graduate student Adrian Price-Whelan, viewed 3D movies with undergraduate Jose Montelongo, and learned about Comet PANSTARRS with Director of Outreach, Summer Ash, and graduate student Yong Zheng. 

Please come see us on April 5th when graduate student, Ximena Fernandez, will present highlights from lesser known space telescopes that are providing astronomers with great glimpses of the Universe. 

--Summer Ash (Director of Outreach)

March 1: Martian Summer

We hosted author, Andrew Kessler, and approximately 80 members of the general public on Friday, March 1st to hear all about the people and the science behind NASA's Phoenix Mars mission. Kessler spent a year with the engineers and scientists who worked on Phoenix to learn what it takes to launch a spacecraft from Earth and safely place it on the surface of another planet. Phoenix landed near the north pole on Mars, the first craft to ever land in the polar regions of the red planet. It's mission was to study the history of water in the ice-rich boundary of the Martian arctic. To do this, the Phoenix lander was equipped with a robot arm that could scoop up soil samples for analysis by an array of instruments including a mass spectrometer, a wet chemistry lab, and a high resolution imager. Not only did Phoenix discover subsurface water ice, but it also found that Martian soil contained high concentrations of chloride which converts to perchlorate in the presence of sunlight. You can read all about the Phoenix mission and Kessler's experience in mission control in his book, "Martian Summer: Robot Arms, Cowboy Spacemen, and My 90 Days with the Phoenix Mars Mission" and you can follow him on Twitter here.

After the talk, audience members toured our rooftop observatory (with the help of graduate students Jennifer Weston and Yong Zheng and undergraduate Jose Montelongo), viewed 3D movies (with undergraduate Bryan Terrazas), and listened to graduate student Steph Douglas explain the myriad of motions experienced by the Earth from our rotation around the Sun all the way out to the expansion of the Universe.

Join us for our next event on Friday, March 15th when post-doc Ashely Pagnotta explains how supernovae are used to understand the mysterious force known as dark energy.

--Summer Ash (Director of Outreach)

November 30: Galactic Neighborhoods

On November 30th, about 100 people joined us to hear Columbia Astronomy Professor Jacqueline van Gorkom talk about how galaxies are influenced by their surroundings. Professor van Gorkom is a radio astronomer and does extensive research on galaxies. She showed us how strikingly different galaxies look in dense clusters of galaxies compared with fields. She explained that when a galaxy enters a galaxy cluster filled with hot intra-cluster gas, the cold gas inside the galaxy gets stripped out of it and thus star formation is quenched, which changes the color of the galaxy from blue to red. The audience raised a lot of interesting questions about galaxies and gravity.

After the talk, some people went to see the 3D movies on the 13th floor shown by Columbia undergraduate student Gladys Velez-Caicedo. Unfortunately, the sky was not clear on Friday, but Columbia Astronomy graduate students Adrian Price-Whelan and Jenna Lemonias gave a telescope tour to a group of people on the roof of Pupin. In the lecture hall, graduate student Yuan Li presented a slide show on spiral galaxies and Dr. Jana Grcevich talked about the Big Bang and the expansion of the universe.

Join us on December 14th for the last event of this semester: a panel discussion on Life, the Universe, and Everything!

--Yuan

May 11: The Immortal Quantum

Our final speaker of the spring was PhD candidate, Cameron Hummels, who traced the path of energy through the Universe from the Big Bang to everyday processes here on Earth. In his usual enthusiastic style, Cameron reviewed the different forms energy can take using both himself and an array of props to demonstrate his points. Laying down the gauntlet for future speakers, Cameron capped his discussion of the conservation of energy with the legendary physics pendulum demo in which he released a x pound weight, attached to the ceiling of the lecture hall, and shut his eyes tightly as it swung away and then back to within millimeters of his chin. A great time was had by all 250+ audience members.

The skies mostly cooperated for visitors to observe some familiar targets such as Mars, Saturn and the Mizar and Alcor star system in the handle of the Big Dipper. Back indoors, graduate student Yuan Li led a discussion on brown dwarfs in the solar neighborhood and graduate student Jana Gcrevich ran our 3D Astro Wall.

On a closing note, Cameron is one of the founders of our outreach program. It's his blood, sweat, and tears that got his fellow graduate students and members of the department motivated to share their knowledge of the Universe with the public, teachers, and students of New York City. Unfortunately for us (but fortunately for the world of astronomy), Cameron is graduating this summer and leaving Columbia for the southwest where he will begin a post-doc at the University of Arizona on galaxy evolution. We wholeheartedly thank him for all his hard work and wish him the best of luck in his future endeavors.

Our summer event series kicks off Friday, June 1st. Stay tuned for more details…

--Summer

February 3: Top 11 Astronomy Stories of 2011

Last night, graduating grad student, Jana Grcevich, kicked off our Spring lecture series by recapping the "Top 11 Astronomy Stories of 2011." Some of the highlights included: the most massive galaxy cluster found, a possible detection of the Higgs boson, a possible detection of a supermassive black hole devouring a star, the 2011 Nobel Prize in Physics going to three astronomers, and the discovery of over 3000 new exoplanets.

Jana ranked the new planet discoveries as number one on her list and many people would agree. Understanding and determining the available real estate for life to grab a foothold in our galaxy, let alone the rest of the Universe, ranks as one of the top 3 questions asked by humanity since humanity could ponder its own existence. Jana explained how the discoveries were made, by the Kepler space telescope, by stating that it measures the dimming of light from a star to determine the nature of the object causing the dimming due to occultation (the object passing in front of the star). She then focused on some of the gems from this exciting database of planets which included the discovery of a super earth-massed planet (roughly 2.5x) orbiting around its star in the habitable zone - an object known as Kepler 22b. Afterwards, she pointed out some planets orbit around binary stars, giving a shout out to the fans of Star Wars who recall Tatooine’s planetary system. Last, but not least, she displayed the best determination for many planetary systems’ orbits and configurations which showed us that planetary systems similar to our own are actually common place and not rare as previous thought based on the planetary systems discovered before the Kepler mission.

Many good questions were asked from the 140+ attendees last night, proving that a recap of the LAST year’s exciting discoveries was a great way to start off THIS year’s lecture series.

--Duane

December 2: Are there other Universes?

Last night we had a fantastic lecture given by postdoctoral researcher David Kagan entitled: "Is Our Universe Alone in the Multiverse?" David covered a full introduction to assure everyone was on the same page for this high-level but philosophically interesting subject. He described the idea of an expanding observable universe, the multiworlds interpretation of quantum mechanics, the inflaton field theory and how it could describe other universes popping into existence ourside of our observable window and more. After his talk, he fielded questions for the remainder of the period from a group of dedicated enthusiasts.

In addition to the lecture, we had great observing conditions on the roof. Adrian Price-Whelan led a crew of graduate volunteers on our telescopes, helping attendees see the Pleiades, the Andromeda Galaxy, the first-quarter Moon, and Jupiter. In addition Yuan Li ran the 3D visualization wall permitting attendess to see simulation results and education movies in 3 dimensional projections. Thanks to all of the 160 people we had turn out!

--Cameron