Astronomy Planet Study Guide Venus-Jupiter
Planetary Study Guide
Mercury * As seen from Earth: * Orbital period of 88 days; rotation to orbit is a 3:2 ratio * Distance from Sun: 0.31 AU to 0.46 AU from the Sun * Eccentric orbit: close and far away (perihelion and aphelion) * 7 percent to the ecliptic * Visible by the naked eye just before sunrise or just after sunset (when the Sun’s light is blotted out) * Never far from the Sun * As a physical body: * Small (about 0.055 Earth’s mass) * No permanent atmosphere; thin envelope of gas temporarily trapped from the solar wind * Surface covered with craters (caused by meteoroids) * Lacks maria like the moon, however * Intercrater plains – craters are less densely packed than the moon * No evidence of plate tectonics like on Earth * Scarps – surface ridges/cliffs (think shriveled apple effect) * Caloris Basin – huge circular basin more than half as wide as Mercury’s radius * Visited by Messenger and flyby done by Mariner 10 * Photographed scarps (ridges) on the surface * Discovered weak magnetic field that suggests iron core
Venus * As seen from Earth * Orbital period of 225 days (Earth days) * Distance from Sun: around 0.7 AU * Slow, retrograde rotation * Reflective cloud covering makes it appear very bright in the sky * Visible by the naked eye 2 hours before sunrise or after sunset * As a physical body: * Size and mass similar to Earth (a little smaller) * Extremely thick atmosphere; nearly opaque to visible light * Consists mostly of carbon dioxide * Surface temperature like hell – greenhouse effect * Surface mostly smooth, resembling rolling plains * Mapped by radio telescopes from Earth * Two elevated continent type regions * Appears to have volcanoes but none confirmed to be active * Some craters * Visited by
Mercury * As seen from Earth: * Orbital period of 88 days; rotation to orbit is a 3:2 ratio * Distance from Sun: 0.31 AU to 0.46 AU from the Sun * Eccentric orbit: close and far away (perihelion and aphelion) * 7 percent to the ecliptic * Visible by the naked eye just before sunrise or just after sunset (when the Sun’s light is blotted out) * Never far from the Sun * As a physical body: * Small (about 0.055 Earth’s mass) * No permanent atmosphere; thin envelope of gas temporarily trapped from the solar wind * Surface covered with craters (caused by meteoroids) * Lacks maria like the moon, however * Intercrater plains – craters are less densely packed than the moon * No evidence of plate tectonics like on Earth * Scarps – surface ridges/cliffs (think shriveled apple effect) * Caloris Basin – huge circular basin more than half as wide as Mercury’s radius * Visited by Messenger and flyby done by Mariner 10 * Photographed scarps (ridges) on the surface * Discovered weak magnetic field that suggests iron core
Venus * As seen from Earth * Orbital period of 225 days (Earth days) * Distance from Sun: around 0.7 AU * Slow, retrograde rotation * Reflective cloud covering makes it appear very bright in the sky * Visible by the naked eye 2 hours before sunrise or after sunset * As a physical body: * Size and mass similar to Earth (a little smaller) * Extremely thick atmosphere; nearly opaque to visible light * Consists mostly of carbon dioxide * Surface temperature like hell – greenhouse effect * Surface mostly smooth, resembling rolling plains * Mapped by radio telescopes from Earth * Two elevated continent type regions * Appears to have volcanoes but none confirmed to be active * Some craters * Visited by