Figure 6-1 RIVUXG Earth-Based Views of Mercury, Venus, and Mars (a) Hazy markings are faintly visible in this photograph of Mercury, one of the best ever produced with an Earth-based telescope. Note that Mercury goes through phases like Venus (see Figure 3-9). (b) Venus at inferior conjunction shows its atmosphere as a faint ring surrounding the planet. This photograph was processed to reveal the ring, which is too faint to show in Figure 3-9. (c) Mars’ polar ice cap is clearly visible on this image made by Jamie Cooper using a webcam.