FIGURE 2.1 Upper: Montage of some of the first extrasolar systems discovered using the radial velocity technique, compared with our inner solar system. SOURCE: Geoff Marcy, University of California, Berkeley, and Paul Butler, Carnegie Institution for Science. Lower: Adaptive optics image obtained at the Gemini and Keck Observatories of three planetary-mass objects orbiting the nearby A star HR 8799. The bright light from the star has been subtracted to enable the faint objects to be seen. A dust disk lies just outside the orbits of the three planets, just as in our solar system the Kuiper belt lies outside the orbit of Neptune at 30 AU. SOURCE: National Research Council of Canada–Herzberg Institute of Astrophysics, C. Marois and Keck Observatory.