The Rio scale is a tool for communicating the significance of a signal to the general public. It assigns scores to signals detected in searches for extraterrestrial intelligence (SETI), which characterizes both the consequences of a signal and the probability the signal is truly from ETI, in an easily digestible format for laypeople to interpret. In the 17 years since its construction, the number of groups actively conducting searches for evidence of intelligent life beyond the Earth has increased significantly, and theoretical work has established a new suite of observables that are capable of revealing the presence of ETI in a range of astronomical observations. In this paper, we revise the Rio scale, with the aim of (i) achieving consensus across academic disciplines on a scheme for classifying signals potentially indicating the existence of advanced extraterrestrial life, (ii) supplying a pedagogical tool to help inform the public about the process scientists go through to develop an understanding of a signal and (iii) providing a means of calibrating the expectations of the world at large when signals are discussed in the media. We also present (and encourage the SETI community to adopt) a single set of consistent terminology for discussing signals.

Commission 53 on Extrasolar Planets was created at the 2006 Prague General Assembly of the IAU, in recognition of the outburst of astronomical progress in the field of extrasolar planet discovery, characterization, and theoretical work that has occurred since the discovery of the pulsar planets in 1992 and the discovery of the first planet in orbit around a solar-type star in 1995. Commission 53 is the logical successor to the IAU Working Group on Extrasolar Planets WG-ESP, which ended its six years of existence in August 2006. The founding president of Commission 53 is Michael Mayor, in honor of his seminal contributions to this new field of astronomy. The vice-president is Alan Boss, the former chair of the WG-ESP, and the members of the Commission 53 Organizing Committee are the other former members of the WG-ESP.

Commission 51 met on 18 August 2006. President Karen Meech chaired the meeting and there were 16 members present, including vice-president Alan Boss, and OC member David Morrison.

In his book Plurality of Worlds, Steven J. Dick (1984) has chronicled the millennia of discourse about other inhabited worlds, based upon deeply held religious or philosophical belief systems. The popularity of the idea of extraterrestrial life has waxed and waned and, at its nadir, put proponents at mortal risk. The several generations of scientists now attending this General Assembly of the International Astronomical Union at the beginning of the 21st century have a marvelous opportunity to shed light on this old question of habitable worlds through observation, experimentation, and interpretation, without recourse to belief systems and without risking their lives (though some may experience rather bumpy career paths). The newly-named and funded, multi-disciplinary field of astrobiology is extremely broad in its scope and is encouraging IAU members to learn and speak the languages of previously disparate disciplines in an attempt to answer the big picture questions: ‘Where did we come from?’, ‘Where are we going?’, and ‘Are we alone?’ These are questions that the general public understand and support, and these are questions that are attracting students of all ages to science and engineering programs. These questions also push the limits of modern instrumentation to explore the cosmos remotely across space and time, as well as to examine samples of interplanetary space returned to the laboratory and samples of distant time teased out of our own Earth.

Within my personal event horizon, the other planetary systems long-predicted by theorists have been uncovered, along with many whose structures were not predicted. The ‘just-so’ conditions requisite for the comfort of astronomers have been understood to be only a very narrow subset of the conditions that nurture extremophilic, microbial life. Thus the potentially habitable real estate beyond Earth has been greatly expanded and within the next few decades it may be possible to detect the biosignatures or technosignatures of inhabitants on distant worlds, should there be any.

The Working Group on Extrasolar Planets (hereafter the WGESP) was created at a meeting of the IAU Executive Council in 1999 as a Working Group of IAU Division III and was renewed for three more years at the IAU General Assembly in 2003. The charge of the WGESP is to act as a focal point for international research on extrasolar planets. The membership of the WGESP has remained unchanged for the last three years.

At the IAU General Assembly in 2000, the Working Group on Extrasolar Planets (WGESP) was established as a working group of Division III. Its terms of reference include acting as a focal point for international research on extra solar planets and organizing IAU activities in the field, such as, organizing comparative reviews of techniques used to detect extra-solar planets and establishing criteria for detections of varying degrees of certainty, as well as maintaining lists of objects satisfying these criteria. The committee is chaired by Alan Boss, and the current members are; Paul Butler, William Hubbard, Philip Ianna, Martin Kiirster, Jack Lissauer, Michel Mayor, Karen Meech, Francois Mignard, Alan Penny, Andreas Quirrenbach, Jill Tarter, and Alfred Vidal-Madjar.

This paper reports new, more sensitive observations of nine of the eleven extrastatistical signals in the Megachannel Extraterrestrial Assay (META). These extrastatistical signals had all of the expected characteristics of extraterrestrial transmissions, except that they did not repeat. Cordes, Lazio, & Sagan (1997) showed that this lack of repeatability could be explained by interstellar scintillation of intrinsically steady sources. We use their methodology and our observations to exclude the scintillation hypothesis at a confidence level of at least 97.8% (for the case of an intrinsically weak source) to a level in excess of 99% (if the source strengths are comparable to that favored by Cordes, Lazio, & Sagan 1997). We also demonstrate that gravitational microlensing cannot account for the initial detection of these candidates nor is microlensing likely to play a role in future SETI programs. We conclude that the META candidates do not reflect a large population of powerful beacons.

The SETI Institute, the California Academy of Sciences, NASA Ames Research Center, and San Francisco State University have developed standards-based curriculum materials for a one-year high school integrated science course centered on the unifying theme of evolution. Scientists, teachers, curriculum writers, and media specialists are currently finalizing six modules that integrate astronomical, geological, and biological sciences as well as the history of science and technology. The sequence of lessons in each module is designed to promote students' understanding and skills as defined by the National Science Education Standards and Benchmarks for Science Literacy. The modules cover: Cosmic Evolution, Planetary Evolution, Origin of Life, Evolution of Life, Hominid Evolution, and the Evolution of Technology. The core lessons for all six modules are provided via CD-ROM, including instructional guidelines, science background information, and additional resources (print, audiovisual, software, WWW sites, and databases). These products will be published as a complete set for use as a yearlong science course and will also be available as individual modules for use in discipline-based courses. Evolutionary change is a powerful framework for studying our world and our place therein. It is a story of epic size, capable of inspiring awe and of expanding our sense of time and place. This story is the basis of Voyages Through Time.

To date, no SETI observing program has succeeded in detecting any unambiguous evidence of an extraterrestrial technology. Regrettably, this paper will therefore not dazzle you with the analysis of the contents of any interstellar messages. However, as is appropriate for a plenary presentation, this paper does provide an update on the state of SETI programs worldwide. It discusses the various “flavors” of observational SETI projects currently on the air, plans for future instrumentation, recent attempts to proactively plan for success, and the prospects for future public/private partnerships to fund these efforts. The paper concludes with some tentative responses to the “What if everybody is listening, and nobody is transmitting?” query.

Because the division consists of many very active commissions, most activities are included in the reports of the individual commissions. This report highlights a small subset of the major achievements that are covered in detail in the reports by the commissions. Some administrative activities of the division and reports of the divisional working groups and committees are also included as subsequent sections of this divisional report.

From February through early June, 1995, Project Phoenix conducted SETI observations of 209 stars over the frequency range from 1195 to 3005 MHz. A byproduct of this search is a unique data set suitable for studying the Radio Frequency Interference (RFI) environment at the Parkes 64-m telescope in New South Wales, Australia. RFI is an increasing problem for SETI and other radio astronomy observations conducted outside of the «protected» frequency bands. The data analyzed for this paper were «mean baseline» spectra in Left and Right Circular Polarization (LCP, RCP), integrated for either 138 or 276 s, covering a 10 MHz bandwidth with 15,552 channels at a resolution of 643 Hz. Channels were identified as contaminated by RFI when the power in the channel exceeded the mean noise by 3%. The «spectral occupancy», the fraction of time RFI was seen, was determined for each channel. The RFI occupancy for LCP and RCP are distinctly different. Approximately 100 MHz of the spectrum was too heavily contaminated for SETI observations.

We conducted a search for narrowband artificial signals from the regions of stars around which planetary companions have been recently found: 51 Pegasi, Gliese 229, 70 Virginis and 47 Ursae Majoris. We used the large Nançay decimetric telescope, with a frequency resolution of 50 Hz, and we scanned over 0.64 MHz and 2.24 MHz respectively around the hydrogen and hydroxyl lines.

If the funding that has been requested in NASA’s FY89 budget is forthcoming, the Search for Extraterrestrial Intelligence (SETI) will inaugurate its microwave search program on Columbus Day, 1992. This systematic search for evidence of narrowband microwave signals generated by another technology will continue at several sites around the world until at least 1998. The search will be conducted in two modes: a sensitive targeted search of selected solar type stars covering 1 to 3 GHz, and an all sky survey that covers 1 to 10 GHz. This region of the spectrum is the quietest in terms of natural background noise from astrophysical sources and/or the terrestrial atmosphere, which is why it was chosen. Unfortunately, at the same time that terrestrial technology has enabled this systematic search, it also threatens to render the search all but impossible from the surface of the Earth. Terrestrial transmissions generated for an enormous number of different purposes will be the signals most frequently detected by the SETI systems! This paper describes the design decisions and observing plans that the SETI Program is now making in order to have a chance of successfully “listening” throujgh this heavily utilized portion of the spectrum. We do not yet know precisely how heroic our efforts to discriminate against and identify RFI may have to be, but we have been accumulating observational experience and data that demonstrate convincingly that the situation is rapidly growing worse. Because of the real-time nature of the signal processing being planned, SETI systems will provide an excellent opportunity to monitor, and perhaps identify, sources of narrowband interference within the radio astronomy bands at each site where observations are being conducted.