Space probes, Voyager 1 and 2, were launched in 1977 to explore outer planets, Jupiter and Saturn then Uranus, Neptune and beyond. The Voyagers are currently continuing their journey beyond our planets and the outer limits of the Sun’s sphere of influence, sending back images as they travel. It’s from images like these, scientists catch a glimpse of what is on other bodies in space and develop an idea of their surface and interior activity. For example, Enceladus, Saturn’s 6th largest moon, has icy plumes emanating from below its surface, with a possible liquid ocean beneath its surface with a source of heat at its interior, that far away from the Sun. It’s icy plumes supply Saturn’s E-ring. Io, one of Jupiter’s largest moons, is the only body in the outer Solar System that is made of rock, erupting hot silicate rock, with ice at its surface – it’s the most geologically active body in the Solar System. As scientists continually collect data, they can piece together the present and past histories of these bodies in space and determine if they are active and whether they have the potential to host life.
The author, Natalie Starkey, a geologist and cosmochemist, defines a volcano to include activity on Earth as well as on other planets, moons and asteroids. She defines Solar System volcanoes as places where fluid from the interior of a planet or moon is erupted. This fluid could be molten rock, any type of gas or even ice. Whatever is being expelled is classified as magma. This is a planet or moon’s way of cooling down, expelling/redistributing its internal heat.
Not all volcanoes look alike, some are steep or have shallow sides. Some form at the boundaries of tectonic plates, some do not – Earth has both. The other planets/moons in our Solar System do not have tectonic plates, only Earth has this unique feature. From observations of volcanoes on Earth – the colors emitted from chemical reactions, what colors are seen at certain temperatures – scientists use this as a guide to interpret images from the Voyager and other spacecrafts.
The author explains that the amount of time it takes for a planet to cool down is important. If it cools down too quickly, losing its internal heat, it becomes a dead planet, with no chance of hosting life. Volcanic activity plays a role in a planet’s environmental development. It must cool at a certain rate so that a level of volcanic activity can be maintained. A planet with volcanic activity is a planet with internal heat at its core, which generates its magnetic field. A magnetic field and preservation of water are important in the development of life as we know it. Without a magnetic field to hold it, liquid water on the surface will be lost to space.
The author also explains how and why Earth has been able to maintain the heat in its core for billions of years, the key to life above, and why other planets and moons have not – So interesting! Each planet heated up and cooled down in its own way. If it cooled down too quickly or too slowly, it has no chance of hosting life.
She describes the unique environments of the planets in the Solar System and what occurred differently in their evolution of cooling to have them arrive at their present volcanic state. A large planet with a thick rocky mantle, like Earth, cools slower than a smaller planet, or one with a small proportion of mantle, like Mercury or Mars. She also explains the circumstances as to how and why these planetary bodies arrived at their size and proportions. Natalie Starkey takes the reader on an amazing journey, by way of space science and volcanic geology, through the Solar System, visiting planets, moons and asteroids.
Reading this book makes you realize how unique or planet Earth is. It’s location and series of ideal events, created circumstances and environments that could host life. No other planet in our Solar System is like ours. We have yet to find even minimal life forms on the planets and moons in our Solar System. Makes you really appreciate Home! For that reason alone, you should give Fire & Ice by Natalie Starkey a read.
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