Astronauts and Moon Landings

Yesterday, we provided a free screening of the film Apollo 13 to an audience of around 120. Erika Hamden and Cameron Hummels introduced the film with a short history of the Space Race along with a few definitions of some jargon terms that were used in the film (e.g. burn, gimbal lock, LEM). The film lasted about 2:20, and the auditorium thermostat seemed broken so the audience got an accurate experience of how cold it was in the broken command module of Apollo 13.

After the film, Erika and Cameron spoke for 20 minutes about how scientifically accurate the film was (very), and then discussed what broke in the actual Apollo 13 service module and why. They presented information about the remainding days of the Apollo program and the followup Shuttle program. Lastly, they gave information on how to go see the remaining shuttle launches and tips for youngsters on how to become an astronaut.

Unfortunately, the sky was cloudy, so we were unable to observe. NASA swag of Hubble Space Telescope photos and stickers for the HST-servicing mission were given out to audience members.

Thanks to everyone who turned out!

--Cameron

Supernovae Lecture and Stargazing: July 2, 2010

This past Friday, recent post-baccalaureate of the Columbia Astronomy program, Nicholas Hunt-Walker, gave a talk entitled, “Supernovae: Going out with a Bang!” In his talk, Nick gave a clear overview of the main points of stellar evolution that lead up to two different types of supernovae: mass-accretion and core-collapse. He told us that mass-accretion type supernovas (also known as Type Ia) arise from binary systems where one star has already gone through all of the evolutionary phases, becoming a hot, dense stellar remnant, called a white dwarf. The other star, being less massive at birth, takes longer to evolve, eventually becoming a red giant star. When this occurs, the red giant star becomes so puffed up that its outer layers are close enough to the white dwarf companion that it becomes more gravitationally attracted to it. Thus, the white dwarf starts to siphon off the envelope of the red giant star and forms an accretion disk around itself. When enough matter has piled on the white dwarf it ignites thermonuclear burning in its core again. However, since it no longer has an envelope of mass around the core like a normal star, it can’t contain the increase in pressure and temperature and thus ignition becomes a runaway event that blows the white dwarf apart!

The second type of supernova (also called Type II) comes from the core collapsing in a massive star that is capable of fusing Hydrogen in its core up to Iron. Once this occurs, the star can no longer create enough energy in the core to support the many solar masses of matter above it. In seconds the star implodes on its self and then blows apart, usually leaving a neutron star or black hole behind. Nick received a myriad of good questions about the particulars of these processes and he patiently responded to everyone who asked.

He then went on to show us many beautiful examples of supernova remnants and how you can tell the difference between the type of supernova that created them from the characteristics of the remnants themselves. One good example of the observational difference is that a core-collapse supernova can have a compact stellar remnant in its center whereas a mass-accretion supernova can’t since the central object is totally destroyed! Nick also told us why we view the spectra of these remnants in different wavelengths like the X-Ray, Radio, and Optical. He explained that with this data we can better figure out what the progenitor star was made of and how and when it exploded.

Finally, Nick shared some historical accounts of famous supernova like the Crab supernova, seen by Chinese and Arab astronomers in 1054, and Tyco Brahe’s supernova, seen by, well, the man himself, in 1572. There continued to be many good questions from the audience about supernovae and their remnants. It was only in the interest of time for observations on the roof that the Q&A session ended.

We had a great turn out and our attendees made full use of our facilities by watching astronomy visualizations on our 3-D wall, ran by graduate student Yuan Li, and by going to the roof to stargaze. It’s cool to think that some of the stars we observed will be become supernovae in the future.

Thanks to the 9 volunteers and the 140+ people who attended our lecture and observing night!

Visitors from Manhattan East School

Today, we had a visit from the Astronomy Club of Manhattan East for the Arts and Academics in East Harlem, NY. A few of the graduate students presented several interactive activities for the club, including a solar-system walk, solar observing, an observatory tour, and a 3D flight through the Universe. In addition, we fielded several questions they had about astronomy, physics, science and college life. They were a great group of kids, and we were happy to have them here!

Thanks to all 15 of our visitors and the 4 volunteers who put this on.

--Cameron

Time Machine: June 18

The free screening of H.G. Wells classic tale “The Time Machine” (1960) drew around 45 viewers this Friday. Following this movie, graduate student Jennifer Weston led a discussion about the film with the audience, and talked about some of the implications of time travel and the ideas behind it.

Some of the topics covered included: Discussing what humans will be like in 800,000 years, with a review of how we’ve changed in the past 800,000 years. We concluded that while the human race could potentially split into two very different species, our time traveler would NOT be able to speak perfect English with them.


How to resolve the apparent paradoxes of time travel. Multiple time lines and predestination were thought to be some possible ways to prevent paradoxes when you attempt to kill your own grandfather. We also introduced the concept of closed time-like curves.


After this, we had an overview of the physics of traveling through time. We reviewed some of the background for Special and General Relativity, light cones, and black holes. Finally, we outlined how one might build a time machine with wormholes and cosmic strings.


Following the movie, telescopes were set up outside on College Walk, manned by a number of students. Passersby were able to see close up views of the beautiful quarter moon, and the planets Mars, Venus, and Saturn, and the stars Arcturus, Mizar and Alcor. Over the course of a bit more than an hour, about 90 people came by to take advantage of the clear night. Thanks to everyone who attended and to those who volunteered!

From Physics 101 to Pigeons

Around 60 people attended our first event of the summer -- a free screening of The Core. Afterwards graduate student Lia Corrales guided the audience in a discussion around two major topics:

(1) Where does the earth’s electromagnetic field come from?
We reviewed the “Physics 101” of generating magnetic fields. We debunked the idea that simple rotation generates the earth’s magnetic field, and explained how much energy it would take to ‘stop’ or ‘reverse’ the rotation. We reviewed some of the scientific research showing that the earth’s magnetic field can have a complicated interior, can change over time, and occasionally switches polarity.

(2) What effect does the electromagnetic field have on life?
We discussed what solar wind does and does not contain, as referenced in the film. The highlight of the evening was the discussion centered on pigeons! We reviewed the scientific article showing that pigeons could sense magnetic fields. However, we also learned that pigeons used landmarks like roads to navigate. We concluded that a change in the earth’s magnetic field would not be enough to disorient pigeons into a kamikaze death dive, but would be enough to force them to ask for directions on the way home.

Unfortunately, the cloudy sky prevented telescope viewing for the night. Fortunately, the summer series of events got off to a great start, thanks to all the people who attended and our five volunteers!

Photographing Extra-Solar Planets

Despite forecasts for bad weather last night, we got some relatively good skies and views of M3 (a globular cluster of stars), Alcor & Mizar (a binary pair of stars in the Big Dipper), and Saturn. There was a wonderful lecture by Anand Sivaramakrishnan, the chief instrumentation engineer at the Museum of Natural History, on the topic of directly imaging extrasolar planets using interferometry. He discussed a new way in which to observe with modern optical and infrared telescopes which provides more information about planetary companions of stars than other methods. This new technique is currently being used on the Gemini telescope and will soon be used on the James Webb Space Telescope, Hubble's successor.

To follow up on the lecture, we showed a couple of short films on various aspects of stars, including the new program: "Journey to the Stars." Additionally, we had a few informal lessons from Jia Liu and Jennifer Weston regarding "Stars" and "Comets and Meteor Showers" to celebrate the Eta Aquarids meteor shower going on last night. There was some NASA poster swag for everyone to take.

Thank you to the 8 volunteers and 75 attendees last night!

April 23: Public Lecture and Stargazing

A beautiful clear night encouraged nearly 100 people to venture to Rutherfurd Observatory where we first hear from Prof. David Helfand about reconstructing cosmic history, atom by atom. Dr. Helfand's talk detailed how the nuclei of atoms could be used to track events in prehistory from the changes in our planet's ecosystem to the very origins of the universe. This engaging talk was a condensed version of his popular Teaching Company series of lectures.

After the fantastic lecture, we heard from graduate student Jana Grcevic about the 20th anniversary of the Hubble Space Telescope. The skies were clear and we got great views of the moon, Mars, Saturn, M13, and other targets that are often difficult to see from Manhattan without the aid of a telescope. All in all, a spectacular evening.