December 6: Comet of the Century?

In the year after Comet ISON's detection in September 2012, many predicted that its close encounter with the Sun would produce a show worthy of the title "comet of the century".  However, as graduate student Erika Hamden showed, Comet ISON's passage was less spectacular than predicted, though no less interesting.  The comet's orbit showed that it came from the Oort cloud, a sphere of small icy bodies surrounding the Solar System.  Objects in the Oort cloud probably spend most of their time around 0.75 lightyears from the Sun, but occasionally a nearby star can perturb the cloud and send comets into the inner solar system.  Since Comet ISON came from the Oort cloud, it hadn't interacted with the Sun before and so it could provide information about the composition of Oort cloud bodies.

Erika played movies like the one above from several space-based solar observatories (i.e., NASA's Solar Dynamics Observatory, NASA's Solar and Heliospheric Observatory, and NASA's Solar Terrestrial Relations Observatory) showing Comet ISON as it approached the Sun and after its closest encounter. Astronomers had predicted that, after it passed by the Sun, Comet ISON would be very bright and spectacular to see. However, the comet broke up when it got close to the Sun.  The movies showed that some bright debris reappeared after Comet ISON passed the Sun, but it faded rapidly, indicating that the comet had fallen apart. Comet ISON was probably a loose ball of ice that was destroyed by the Sun's heat, like a poorly-made snowball that falls apart before reaching its target.  Although it was not the "comet of the century", Comet ISON provided astronomers with plenty of information about Oort Cloud comets and provided everyone with a great show.

Clouds and rain prevented any roof activities, but undergraduate Claire Ding showed 3D movies on the 13th floor, and graduate student Andrew Weis gave a slideshow of highlights of the winter sky in the lecture hall.

--Steph Douglas (graduate student)

November 22: From the Ashes of Cosmic Explosions...

How did we get here?  Jeremiah Murphy, a new faculty member at Florida State University, shared with us the astronomical answer to this age-old question.  Or, rather, he answered the question of how his dog got here.  He traced the history of the elements in his dog's body, starting with the hydrogen and helium that formed in the Big Bang.  Those lighter elements were fused into heavier elements in the cores of massive stars and in supernovae, the explosions of those same stars.  Supernovae occur when iron builds up in the core of a massive star until that iron cannot support its own weight. Jeremiah showed us the results of his simulations showing how the iron core collapses, producing a blast wave and a wave of sub-atomic particles called neutrinos.  Those two waves tear the star apart in under a second.  The energy produced allows the production of all the elements up to uranium.

Although it was cloudy, graduate student volunteers Jeff Andrews and Andrew Emerick gave tours of our rooftop observatory after the lecture.  Other attendees visited the 3D wall, where graduate student Yuan Li showed off 3D movies about the universe.  In the lecture hall, Summer Ash and graduate students Jingjing Chen and myself answered questions and collected survey results about the night's events.  I also gave a short slideshow on supernovae that were seen on Earth and recorded in historical documents.

--Steph Douglas (graduate student)

November 8: Astronomer vs Astronomer

Scientists do not always agree with each other, and many times, scientific progress is made through debates. On Friday, November 8th, graduated student Jennifer Weston gave a public lecture about a few of the greatest arguments in astronomy in the past 150 years, and how they were resolved. One of the biggest debates in the history of astronomy and astrophysics, the 'Great Debate', was about whether the Milky Way, our own galaxy, was the entire universe, or there were other galaxies out there, seen as the "spiral nebulae". The debate was eventually resolved by the work of Edwin Hubble, which shows that the spiral nebulae are not only galaxies outside of our own, but they are also moving away from us at high speeds. 

After the lecture, many people went to the roof where graduate student Adrian Price-Whelan showed off the Moon and Albiero along with Andrew Emerick, Susan Clark, Aleksey Generozov, and David Jaimes. On the 13th floor, visitors enjoyed 3D astronomy movies with Barnard student Gladys Velez-Caicedo. In the lecture hall, graduate student Yuan Li presented a slide show on planets outside the solar system found by NASA's Kepler telescope. 

Join us on November 22 for a lecture by Jeremiah Murphy on supernova explosions.

-- Yuan Li (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)

September 27: Voyager's Venture

The Voyager satellites are currently the furthest man-made objects from Earth.  Launched in 1977, these satellites are now at the edge of our solar system.  In his lecture, PhD student David Hendel took the audience through the story of this highly successful mission, from the initial design of the satellites to their current status past Pluto.  Taking advantage of a unique planetary alignment, David explained how the NASA scientists were able to set the instruments on a Grand Tour, flying by all of the planets on their way out of the solar system.  This tour has produced some of the highest quality images of the planets to date.

After the lecture, bad weather prevented observing.  Yet those who stayed were able to enjoy roof tours, to view our 3D wall or to listen to a description of the moons of our solar system and their naming history.  

-- Lauren Corlies (graduate student)

September 13: Fossils of Formation

On Friday, September 13th, we launched our 2013 Fall Public Lecture & Stargazing series with a talk on the Milky Way. Post-doctoral researcher, Allyson Sheffield, presented what we currently know about the formation of our galaxy. It turns out that galaxies formed in a hierarchical manner after the Big Bang, with small clumps of gas and dust forming stars, then clusters of stars, and eventually protogalaxies and galaxies. In essence, all galaxies form by accreting other galaxies in a process called galactic cannibalism. Allyson's work deals with observing tidal streams surrounding our galaxy and tracing them back in time and space to determine what structures they originally came from. She is currently focusing her efforts on the Triangulum-Andromeda over-density.

After the lecture, many visitors headed to the roof for some clear sky observing of the Moon, Mizar and Alcor, Alberio, and the Ring Nebula while others remained in the lecture hall to hear about the recent news of the Voyager 1 probe entering interstellar space.

Friday's volunteers included graduate students Jinjing Chen in the lecture hall, Adrian Price-Whelen, Susan Clark, Steven Mohammed, Doug Thornhill, and Yuan Li on the roof, and undergraduates Gladys Velez-Caicedo and Varad Srinivasan on the 3D Wall.

Join us for our next event on Friday, Sept. 27th to hear more on Voyager 1!

--Summer Ash, Director of Outreach

June 14: Cowboys & Aliens

Last Friday, June 14, we screened the joint Western+SciFi action film "Cowboys & Aliens" for an audience of enthusiastic movie-goers. We started the night with a short film, "The Shot", a 5-minute piece about a magical camera lens that works as a teleportation device. The short portrays a man who finds and then uses the lens to travel the world, but trouble arises when he accidentally takes a photo that has him travel out of this world!

The feature, "Cowboys & Aliens", is a genre-mashup that asks "how would a pre-1900, small western town handle an alien invasion?" The answer is: Daniel Craig, the film's leading actor. The film combines references to classic western films like "A Fistful of Dollars" alongside clear homage to sci-fi movies such as "Alien" and "Close Encounters of the Third Kind" (up next in our summer film series). Though there is not much science to discuss in the movie, we did estimate that the height of the alien rocket is about ~3 times the size of a Saturn V at about ~10 times the width. One wonders how the aliens use gold as a power source for such a large vessel...

Join us next time on July 12th for our next Summer Film & Stargazing Event!

--Adrian Price-Whelen (graduate student)