Dr. Christine Jones President, American Astronomical Society Before the U.S

Statement of Dr. Christine Jones President, American Astronomical Society before the U.S. House of Representatives Committee on Science, Space and Technology Subcommittee on Space and Subcommittee on Research and Technology July 12, 2016 Chairman Babin, Chairwoman Comstock, Ranking Member Edwards, Ranking Member Lipinski, and members of the Subcommittees, I am pleased to have the opportunity, as the President of the American Astronomical Society, to summarize the state of US astronomy as supported through the Federal agencies NASA and NSF. I provide examples of cutting edge astrophysical research, emphasize the importance of supporting basic science research, list the important research questions and outline how future missions will address them. To begin, I would like to thank Congress for supporting the exploration of the Universe through NSF and NASA. Federal support for astrophysical research has been absolutely essential to all the recent major advances we have made in understanding the mysteries of the Universe. Although I was not asked to discuss planetary science or solar physics today, I would be remiss if I did not mention that many members of the American Astronomical Society perform exciting planetary and heliophysics research with the support of NASA and NSF. NASA planetary science includes the New Horizons close-approach of Pluto and Charon, and the Juno mission that just successfully began orbiting Jupiter. An asteroid sample-return mission, OSIRIS-REx, is scheduled for launch in September this year. Heliophysics includes ongoing and detailed studies of the Sun, which facilitates our ability to predict potentially devastating space weather events, and the Solar Probe Plus mission that will be launched in 2018 will “skim” the surface of the Sun. NSF’s Daniel K. Inouye Solar Telescope (DKIST) will revolutionize our understanding of the Sun when it begins operations in 2019. WHY ASTRONOMY MATTERS Throughout history, astronomy has provided fundamental contributions to science and insights about the nature of our Universe. Over several centuries, our view of the Universe and our place in it has changed dramatically. Copernicus revolutionized our view, in the early 1500’s, when he proposed that the Sun and not the Earth was the center of the Universe. Kepler demonstrated how planets in our solar system 1 orbit the Sun. This work provided part of the foundation for Isaac Newton’s theory of universal gravitation. However, early in the 20th century, there was still considerable question about the size and extent of the Universe. In 1920, in the Baird Auditorium at the Smithsonian Natural History Museum, the “Great Debate” between Harlow Shapley and Heber Curtis concerned whether the Milky Way was in fact the entire Universe as argued by Shapley, or if the Milky Way was a galaxy similar to the Andromeda nebula and other nebulae, as argued by Curtis. The debate did not resolve this question. It was only through Edwin Hubble’s observations of variable stars in other nebulae that it became clear that our Milky Way is only one of many galaxies in the Universe. Even before Earth’s place in the Universe was known, astronomy played critical roles in early navigation and timekeeping. In modern times, the observations of the 1919 solar eclipse were important in proving Einstein’s theory of general relativity. The scientist Ralph Fowler developed the concept of electron degeneracy to explain white dwarf stars, long before this concept was established in solid state physics. Also from astronomy research, we have learned that heavy elements, including the oxygen we breathe, the calcium in our bones, and the gold in our wedding rings are all produced by stars. THE BIG QUESTIONS FOR ASTRONOMY Part of astronomy’s appeal to the public and scientists alike is that it seeks to answer the “big” questions: - How did the Universe come to be? - Are there other Universes? - Is General Relativity correct? - What is dark matter? - What is the nature of the dark energy that causes the acceleration of our expanding Universe? - How do the components of the Universe change over cosmic time? - What new exotic transient phenomena does the Universe contain? - How are stars and planets formed? - Is there water on other worlds outside our Solar System? - Are there Solar Systems like our own in the nearby Milky Way Galaxy? - What were the first stars and galaxies like? - How did galaxies grow across cosmic time to form Milky Way like systems? - Are we alone? These questions excite not only professional astronomers, but the public as well, from children to seniors. To answer these questions and many more, we need large telescopes on the ground and in space that cover the electromagnetic spectrum from long wavelength radio observations to X-rays and gamma rays. As part of answering these questions, we engage students in STEM fields and spawn new technologies that impact our daily lives. As Chairman Smith has said so well in the past “Space exploration is an investment in our future – often the distant future. It encourages innovation and improves Americans’ quality of life. It inspires the next generation to pursue careers in math, engineering, science, and technology.” Chairman Smith’s statement is still true today. 2 Figure 1. The small scale anisotropies of the cosmic microwave background (CMB) as observed by the Planck satellite. The CMB is a snapshot of the oldest light in our Universe, imprinted on the sky when the Universe was just 380,000 years old. The observed fluctuations reflect tiny temperature fluctuations that trace the seeds of the structures that are observed today. The observed fluctuations are used to derive the precise cosmological parameters that characterize today’s “precision cosmology”. (Credit: ESA and the Planck collaboration) RECENT DISCOVERIES IN ASTRONOMY Now is a very exciting time to be an astronomer. New discoveries are challenging what we thought we knew about our Universe. When I was a student in the 1970’s, much about what we know today about the Universe was not known or was very uncertain. For example, even the age of the Universe, a very basic and fundamentally important property, was very uncertain. There were two distinct scientific camps. One group of scientists argued, based on their observations, that the Universe was about 19 billion years old, while the other argued the Universe was significantly younger, only about 9.5 billion years old. Today our knowledge of the Universe is far better then when I was a student. Much of the basic information about the early Universe is imprinted on the Cosmic Microwave Background (CMB), the nearly uniform 3 degree radiation that permeates our Universe. This "afterglow" of the Big Bang has traveled to us from the “surface of last scattering” after electrons, protons, and helium nuclei formed hydrogen and helium atoms, allowing light to travel great distances without scattering off free electrons. Based on analysis of the sky maps of the CMB made by the US WMAP (Wilkinson Microwave Anisotropy Probe) mission and the ESA-US Planck mission (Fig 1), we now know the time since the Big Bang (the age of the Universe) is 13.80+/- 0.02 billion years, measured to an accuracy of 0.14%! 3 Observations from the Planck and WMAP missions also determined that matter makes up only 31% of the Universe, while 69% of the Universe is in the form of the still mysterious dark energy which drives the accelerating expansion of the Universe. And of the 31% of the Universe that is matter, most of this, 81%, is dark matter. Although dark matter emits no radiation, its presence can be inferred in individual galaxies by the motions of stars and gas and in galaxy clusters by their ability to gravitationally bind galaxies and the hot intracluster medium. This hot gas, which fills the entire volume of massive clusters, is visible through its X-ray emission and makes up most of the “normal” matter in clusters, with three to five times more mass in hot gas than in all the galaxies in the cluster (see Fig. 3). But recall that dark matter makes up the bulk of the mass in clusters. When I was a student, no planets had been found outside our Solar System. In 1992, radio astronomers Wolszczan and Frail announced their discovery of two planets orbiting a radio pulsar. In 1995, astronomers Mayor and Queloz, from the University of Geneva announced the definitive detection of a planet orbiting a normal star 51 Pegasi. Although in 1988, three Canadian astronomers (Campbell, Walker, and Yang) published the first suggestion of planets orbiting the star Gamma Cephei, these exoplanets were not confirmed until 2003. NASA’s Kepler mission, launched in 2009, has now discovered 2373 confirmed exoplanets (out of 4943 candidate exoplanets). The discovery of thousands of planets around stars in our Galaxy by the US Kepler mission has shown us the great variety of stellar-planetary systems, including Kepler 16b, the Tatooine system where the planet orbits its two Suns (Fig 2) and very recently, a planet orbiting three stars was reported! The great variety of planetary systems is forcing us to re-examine how planetary systems are formed. In 2017, NASA’s Transient Exoplanet Survey Satellite (TESS) will be launched with the primary goal of detecting small planets with bright host stars in the solar neighborhood, which will allow detailed follow-up observations of the planets and their atmospheres by the next generation of instruments and large space- and ground-based telescopes to search for evidence of extraterrestrial life. The Gemini Planet Imager is now directly imaging massive exoplanets to determine masses and compositions. Figure 2. This artist's concept illustrates Kepler-16b,aka Tatooine, the first planet known to definitively orbit two stars - what's called a circumbinary planet.

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