Distant Giants: Jupiter and Saturn

  • Francis Reddy
Part of the Patrick Moore's Practical Astronomy Series book series (PATRICKMOORE)


After following the frenetic wanderings of Mars, we turn now to planets that proceed through the sky at a much more leisurely pace. Jupiter and Saturn, the largest planets of the solar system, lie much farther from the Sun – and us – than Mars. Jupiter’s lane of the solar system racetrack is about five times the size of Earth’s, and Saturn’s track is nearly twice as large as Jupiter’s. Their wanderings through the constellations are much less dramatic than the splendid whirl of Mars, but the motions are similar, with retrograde loops centered on the time when they’re opposite the Sun in our sky. As with Mars, Jupiter and Saturn come to opposition when our faster-orbiting Earth overtakes and passes them, and this is the time when they’re closest, shine brightest and appear largest in a telescope. However, their slower orbital speeds translate to more frequent oppositions: Jupiter’s recur every 13 months, while Saturn’s happen a couple of weeks later each year (see Appendix D for details). Their plodding regularity results in seasonal appearances that approximate those of the background stars. Jupiter travels through roughly one constellation of the zodiac each year and Saturn tracks about half that, so skywatchers can count on seeing these planets only slightly later each successive year. A special treat occurs about every two decades, when Jupiter overtakes Saturn and the solar system’s biggest worlds shine in tight formation.


Solar System Giant Planet Galilean Satellite Planetary Scientist Metallic Hydrogen 
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Copyright information

© Springer Science+Business Media, LLC 2012

Authors and Affiliations

  • Francis Reddy
    • 1
  1. 1.Syneren Technologies Corp.LanhamUSA

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