The Fate of the Planets

The fate of the planets is tied to their star. Earth has maintained oceanic conditions for billions of years, facilitating biological evolution. As the sun grows hotter, Earth's conditions will change, eventually leading to the end of complex life. The sun will expand into a red giant, potentially engulfing inner planets.

Voyager reveals Uranus as an ice giant with cold temperatures and rings. Its bizarre, tilted orientation suggests a collision with an Earth-sized object early in its formation, explaining both its tilt and its coldness.

Saturn's weather is driven by an internal heat source, not sunlight. Deep inside, extreme pressure transforms methane into diamond rain, which eventually dissolves. The heat source is generated by molten helium falling through liquid metallic hydrogen.

The Mars Reconnaissance Orbiter reveals evidence of an ancient sea in the Aidonia Basin with hydrothermal vents, similar to early Earth. Mars underwent climate change, becoming colder and volcanically active. The planet lost its magnetic field, leading to the stripping away of its atmosphere and water.

Neptune, an ice giant, features supersonic winds and immense dark vortices. It is warmer than Uranus, possibly due to pressure turning carbon and methane into diamond rain, which melts and releases heat.

Messenger's mission to Mercury reveals a planet with a large core and volatile elements on the surface, suggesting it may have formed further from the sun. A collision may have stripped away its crust, leaving a metallic core.

Earth's magnetic field protects it from the solar wind. Mars once had a magnetic field, but it died out, leading to the loss of its atmosphere and water. Mars's smaller size caused its core to cool more quickly, ending its magnetic field.

Saturn's rings likely formed from a moon that got too close and was ripped apart by Saturn's gravity. Cassini reveals the rings' complex structure, including vertical structures and moon-sized chunks of ice.

Jupiter spiraled inwards, disrupting the asteroid belt and scattering material. It stunted the growth of Mars and may have prevented the formation of super-Earths. Saturn caused Jupiter to retreat, allowing the inner planets to form.

Jupiter's outward movement delivered water to the inner solar system. It also protects Earth from asteroids and comets. Jupiter cleared the way for humans by driving the dinosaurs to extinction.

Jupiter protects Earth from objects from the outer solar system. The Galileo mission witnessed Comet Shoemaker-Levy 9's impact on Jupiter, demonstrating the planet's ability to act as a shield.