Professor explains extrasolar planets


By Saj Sri-Kumar

UCLA Astronomy Professor Michael Jura (Michael ’99) spoke about the search for extrasolar planets and the difficulty of finding terrestrial planets similar to Earth capable of supporting life during an optional assembly on Monday morning in Ahmanson Lecture Hall.

The event, which was held during the Upper School’s regular Monday break, was attended by around 40 students. The event was part of the school’s Science, Technology, Engineering and Mathematics initiative, which aims to further students’ understanding of the opportunities in those fields.

Jura was invited to speak by physics teacher Antonio Nassar, who met Jura when he taught Jura’s son.

Jura described the trouble that astronomers have had in finding terrestrial planets similar to Earth—so far, the vast majority of the roughly 400 planets that have been found have all been large gas giants, similar to Jupiter in our solar system. Earth, with a high volume of oxygen, iron, silicon and magnesium, has a vastly different composition than Jupiter, which is mainly composed of gaseous hydrogen and helium. Jura, however, expressed a hope that NASA’s Kepler Mission, which was launched this past March, would help them find Earth-like planets.

Jura elaborated on two methods of finding extrasolar planets. The first is to detect a decrease in light emission from a star when a planet passes between it and the earth, partially deflecting the light. This method has been successful in detecting gas giants, similar to Jupiter, which could deflect around 1 percent of the light; however, the process is not as effective in detecting smaller, Earth-sized planets, because the Earth, for example, would only deflect around 0.01 percent of the sun’s light—not enough to be detected.

The second method is to look at “polluted white dwarfs.” This method entails looking at dense, high-gravity stars known as white dwarfs.

These stars could have drawn in with their gravity a minor rocky planet. The remnants of the planet can be observed, since the star (which would have normally consisted of mainly gaseous non-metals) can now be found to contain metallic, rock-forming elements such as iron.

This method was used to find a small, asteroid-sized planet near the white dwarf GD 40.

Jura said that astronomers are also aiming to find water on other planets, since it has been found on various moons in our own solar system. Scientists believe that water may be a necessary factor for life.

Jura showed the audience the cover of Isaac Azimov’s novel “Pebble in the Sky,” which involved humans interacting with life on other planets, and remarked that the book was “completely science fiction” when he was growing up; at the time, there was no evidence of life outside the earth.

However, Jura expressed his personal opinion that life will, in fact, be found at some point outside of Earth.