Last January, the National Science Foundation, the Thirty Meter Telescope, and DISCOVER cosponsored a panel discussion at CalTech between DISCOVER/Bad Astronomy blogger Phil Plait and four of the nation's leading astronomers and astrophysicists: Mike Brown, Debra Fischer, Andrea Ghez, and Saul Perlmutter. The researchers touched on topics from newly discovered objects in our solar system to the black hole in our galaxy to the expansion of our universe. 

Here's video of the event presented in four parts, with lots of great questions from the audience. For a transcript of the event, check out the accompanying magazine feature. (Also see video from the NSF and DISCOVER's earlier panel, Unlocking the Secrets and Powers of the Brain.)



 

 

 

More on the panelists:

Mike Brown Caltech
A professor of planetary astronomy, Brown specializes in detecting bodies large and small in the outer realms of the solar system. He has detected three of the five official dwarf planets, including 1,500-mile-wide Eris, which is actually bigger than Pluto. The discovery of Eris led to the controversial demotion of Pluto from “planet” to “dwarf planet” status. (Unlike the eight planets, dwarf planets are not massive enough to clear away other objects from the region around their orbits.) Brown focuses on the Kuiper belt, a zone stretching from Neptune’s orbit, about 3 billion miles from the sun, to 5 billion miles out. The Kuiper belt is similar to the asteroid belt between Mars and Jupiter, but it is filled with icy rather than rocky objects. Some of these bodies are bizarre, including the football-shaped Haumea, another dwarf planet—discovered by Brown in 2003—which hurtles through space end-over-end, flanked by two moonlets. Brown also studies the Oort cloud, a putative bubble of icy material that spawns comets and may extend out a light-year or more. He publishes a weekly astronomy column at www.mikebrownsplanets.com.

Debra Fischer San Francisco State University
Fischer is a professor of astronomy who is at the forefront of the search for exoplanets—planets orbiting other stars. She has contributed to the discovery of about 160 such worlds, roughly half the total number known. In 1999 she helped discover that the nearby star Upsilon Andromedae has three planets, the first hint of an alien planetary system like our own; in 2007 she led a team that found a five-exoplanet system, the biggest yet found. Fischer locates these planets indirectly, by watching how some stars wobble slightly due to the pull of nearby planets orbiting them. Her discoveries have helped guide other astronomers, who are now using complementary techniques to study the temperature and composition of exoplanets, and even in one case to image a planet directly. Most of the newfound planets are blazing-hot Jupiter-like bodies, but Fischer and her colleagues are closing in on smaller “super-Earths.” The recently launched Kepler space probe should allow astronomers to find Earth-size planets with the best chance for harboring life.

Saul Perlmutter Lawrence Berkeley National Laboratory and University of California at Berkeley
Saul Perlmutter is an astrophysicist who has made a career of studying the history and fate of the universe. By measuring the brightness of certain types of exploding stars, called type 1a supernovas, researchers can pin down the distance to the star’s host galaxy. Using these data, in 1998 Perlmutter’s Supernova Cosmology Project and a competing team gave cosmology its biggest shake-up since 1929, when Edwin Hubble showed that the universe is expanding. Most scientists had assumed that gravity must steadily slow that expansion, possibly eventually leading to a contraction that would end with a Big Crunch. Using supernovas to reckon the expansion rate of different parts of the universe, Perlmutter and his group found that the universe is not slowing down at all—in fact, the expansion is accelerating. His discovery indicates that space is filled with dark energy, a mysterious “antigravity” entity that makes up more than 70 percent of the total mass and energy of the universe. The nature of dark energy remains a total enigma.

Andrea Ghez University of California at  Los Angeles
A professor of astronomy and physics, Ghez has mapped the heart of the Milky Way in unprecedented detail. This effort has revealed that at the center of our galaxy is a supermassive black hole almost 4 million times the mass of the sun. For years astronomers had seen evidence of monster black holes in the hearts of other galaxies. These objects cannot be seen directly, but they make their presence known by shooting out bright jets and emitting powerful blasts of X-rays as gas falls in toward them. The Milky Way produces no such fiery outbursts, but scientists had suspected that our galaxy harbors a black hole nonetheless. Ghez was able to prove it is there, publishing her first paper on the topic in 1997. Massive black holes now seem to be a common feature of the way galaxies form. Using the Keck telescope in Hawaii to peer at the heart of the Milky Way in extraordinary detail, Ghez’s team has also found bright, young stars orbiting the hole at up to 3 million miles per hour—among the fastest-moving stars ever observed.

Phil Plait The Bad Astronomer at Discover Magazine