I am very pleased to welcome you to the Fulbright Symposium 2002, Science Education in Partnership, held in conjunction with the Bioastronomy Symposium. I know you will all want to join me in offering our thanks for the beautiful Aboriginal welcoming ceremony. It was particularly meaningful for me. My first trip to this country was in 1966 when I was engaged in medical fieldwork in Western Australia that included members of the Aboriginal community. The ceremony connects this meeting with the earliest human history of this fascinating continent.

Examination of ∼2000 sun–like stars has revealed 97 planets (as of 2002 Nov), all residing within our Milky Way Galaxy and within ∼200 light years of our Solar System. They have masses between 0.1 and 10 times that of Jupiter, and orbital sizes of 0.05–5 AU. Thus planets occupy the entire detectable domain of mass and orbits. News & summaries about extrasolar planets are provided at: http://exoplanets.org. These planets were all discovered by the wobble of the host stars, induced gravitationally by the planets, causing a periodicity in the measured Doppler effect of the starlight. Earth–mass planets remain undetectable, but space–based missions such as Kepler, COROT and SIM may provide detections of terrestrial planets within the next decade.

The number of planets increases with decreasing planet mass, indicating that nature makes more small planets than jupiter–mass planets. Extrapolation, though speculative, bodes well for an even larger number of earth–mass planets. These observations and the theory of planet formation suggests that single sun–like stars commonly harbor earth–sized rocky planets, as yet undetectable. The number of planets increases with increasing orbital distance from the host star, and most known planets reside in non–circular orbits. Many known planets reside in the habitable zone (albeit being gas giants) and most newly discovered planets orbit beyond 1 AU from their star. A population of Jupiter–like planets may reside at 5–10 AU from stars, not easily detectable at present. The sunlike star 55 Cancri harbors a planet of 4–10 Jupiter masses orbiting at 5.5 AU in a low eccentricity orbit, the first analog of our Jupiter, albeit with two large planets orbiting inward.

To date, 10 multiple–planet systems have been discovered, with four revealing gravitational interactions between the planets in the form of resonances. GJ 876 has two planets with periods of 1 and 2 months. Other planetary systems are “hierarchical”, consisting of widely separated orbits. These two system architectures probably result from gravitational interactions among the planets and between the planets and the proto-planetary disk out of which they formed.

Current and future planet search strategies are reviewed.

Due to their extremely small luminosity compared to the stars they orbit, planets outside our own Solar System are extraordinarily difficult to detect directly in optical light. Careful photometric monitoring of distant stars, however, can reveal the presence of exoplanets via the microlensing or eclipsing effects they induce. The international PLANET collaboration is performing such monitoring using a cadre of semi-dedicated telescopes around the world. Their results constrain the number of gas giants orbiting 1–7 AU from the most typical stars in the Galaxy. Upgrades in the program are opening regions of “exoplanet discovery space” – toward smaller masses and larger orbital radii – that are inaccessible to the Doppler velocity technique.

Among the billions of planetary systems that fill the Universe, we would like to know how ours fits in. Exoplanet data can already be used to address the question: How common are Jupiters? Here we discuss a simple analysis of recent exoplanet data indicating that Jupiter is a typical massive planet rather than an outlier. A more difficult question to address is: How common are Earths? However, much indirect evidence suggests that wet rocky planets are common.

We discuss the difficulties of forming earth-like planets in metal-poor environments, such as those prevailing in the Galactic halo (Pop II), the Magellanic Clouds, and the early universe. We suggest that, with fewer heavy elements available, terrestrial planets will be smaller size and lower mass than in our solar system (solar metallicity). Such planets may not be able to sustain life as we know it. Therefore, the chances of very old lifeforms in the universe are slim, and a threshold metallicty (90% solar?) may exist for life to originate on large enough earth-like planets.

Comparative analysis of the parent stars of extrasolar planetary systems and the local disk population shows a strong trend for increasing frequency with increasing abundance. Approximately 4.5% of solar-abundance (−0.15 < [m/H] ≤ +0.15) stars have detectable planetary-mass companions.

The primary conflict between studies attempting to measure 6Li in stars harboring planets, a potential indicator of planet formation, is the incompleteness and inaccuracy of current line lists for the lithium region. We are attempting to resolve these issues using very high-resolution (R ∼ 120,000) and very high quality (S/N between 250 and 1000) spectra of stars with a range of abundances.

An image of the disk of the TTauri star HL Tau at 1.4 mm wavelength at an angular resolution of 0.25 arcsec shows a secondary peak in the disk at a radius of 70 AU and position angle of −40°. This secondary peak is evidently a small unresolved nebulosity which may surround a star or planet or may not yet have formed such a body. The nebulosity could have formed as a result of a density wave instability in the disk.

Astrometry is the most powerful technique to determine dynamical masses and orbital parameters of extrasolar planets. The careful selection and characterization of reference stars is crucial for the success of any astrometric program. The best reference stars for NASA's Space Interferometry Mission (SIM) are distant K giants. The first sub-stellar companion to a K giant was recently detected serendipitously in a radial-velocity survey aimed at defining the SIM grid star strategy.

The study of extra solar planets represents a new exciting frontier for modern astronomy. Most of the results on extrasolar systems are obtained with Doppler surveys. Here we suggest a different approach aimed to study the polarimetric properties of the residual interplanetary dust. Dust can produce observable effects such as infrared emission excess (Beckwith & Sargent 1996; Spangler et al. 2001) and partial polarization of the star light via scattering (Mauron & Dole 1998; Yudin 2000), like in β Pictoris (Voshchinnikov & Krügel 1999). Some polarization could also be produced by a giant planet in a close orbit around the star (Saeger et al. 2000), but the resulting effect is too weak to be responsible for the polarizations actually observed.

By virtue of their planetary-scale magnetic fields, the Earth and all of the gas giants in our solar system possess solar-wind deformed magnetospheres. The magnetic polar regions of these “magnetic planets” produce intense, aurora-related radio emission from solar-wind powered electron currents. Simple scaling laws suggest that Jovian-mass planets close to their host stars should produce radio emission; detecting such emission would be the first direct detection of many of these planets. We describe searches using the Very Large Array (VLA) for radio emission from the planets orbiting HD 114762, 70 Vir, and τ Boo. Our limits are just above those predicted for the planetary emissions. We discuss the possibilities for more stringent limits and the implications that the existing observations have for the planets' radio emissions, and hence on the planetary magnetic fields and stellar wind environments.

The presence of an extrasolar planet can be revealed when it passes in front of its host star, reducing the star's apparent brightness by ∼ 1%. We are monitoring a large sample (of order 104) of stars using our own 0.5 m telescope at Siding Spring Observatory, Australia, in search of such transiting planets.

We investigate the improved detection of extrasolar planets around eclipsing binaries using eclipse minima timing and extrasolar moons around transiting planets using transit timing offered by the upcoming COROT (ESA, 2005), Kepler (NASA, 2007), and Eddington (ESA 2008) spacecraft missions. Hundreds of circum-binary planets should be discovered and a thorough survey of moons around transiting planets will be accomplished by these missions.

Borucki & Summers (1984) have suggested that extrasolar terrestrial planets can be detected by looking for transits. A discussion is presented of a model used to estimate the number and distance of stars for which planets can be detected as a function of spectral type and luminosity class, apparent brightness, planetary size and orbit, and realistic noise sources that must be considered. A choice for an optimum location of the field to search is described given the realistic constraints of a space mission and maximizing the number of available stars.

We present preliminary analysis of new HST observations of the transiting extrasolar planet HD 209458b. Photometric observations were obtained with the Fine Guidance Sensor (FGS) on the Hubble Space Telescope (HST), providing milli-mag precision and high time resolution (40 Hz). The FGS photometry allows us to derive precise stellar/orbital parameters (ephemeris, inclination, limb darkening) and planetary radius, and also allows a search for the presence of planetary rings and satellites. We discuss preliminary results and two approaches to modelling the observations.

We have developed and tested a wide-field photometer to detect extrasolar planet transits from the South Pole. The discovery of transiting planets for which masses can be measured by radial velocity is vital to constrain the models of planet formation and evolution. Short of going to space, the South Pole is the best site from which to carry out a such a survey. Based on results from the Doppler velocity surveys and the Vulcan transit search, we expect to detect 10 to 15 transiting planets in two years of operation at the South Pole.