Monday, February 15, 2016

Earth's Attic: Our Moon by Elaine Scott


In a way, the moon is like an attic. Closer to Earth than any other object in the solar system, the moon has remained nearly undisturbed since it formed. And like any good attic, our moon has stored clues, but to a much earlier time, billions of years ago, when the solar system was new.

These clues from the moon can give geologists--scientists who study the composition of Earth--information about the earliest days of our planet.

Why study the moon? Why send humans to our moon?

Humans have always wanted to know more about our closest space companion. Ancient storytellers and scientists speculated about the moon from earth. And then advances in technology and powerful geopolitical competition fostered direct examination by humans of the moon's surface during the Apollo missions. Now moon probes and astro-robots from Russia, the U.S, Japan, China, and India have added much to our knowledge, including the 2009 U.S. LCROSS mission which found water encased in lunar rocks. The presence of water is a big deal, making it conceivable that moon colonists could extract drinkable water and extract its components--oxygen to breathe and hydrogen as fuel for heat, light, and return rocket engines.

Why go? One good reason is to find out more about how our Earth formed. Visiting the moon is a time-travel mission, a chance to examine a sort of time capsule of early Earth, to see what the dust and rocks there, unchanged for eons by atmosphere and weathering, can tell us about our planet's beginnings. The prevailing theory is that the moon was formed during the formation of the solar system by the collision of a space object the size of Mars with the Earth. This "impact theory" holds that the explosion sent part of Earth's material into space to form the moon. This means that the moon's rocks are basically those of the infant Earth.

Elaine Scott's forthcoming Our Moon: New Discoveries About Earth's Closest Companion (Houghton Mifflin Clarion, 2016) is an up-to-date compendium of knowledge about our next-door space neighbor. Scott begins with ancient moon mythology and science about the moon, the scientists and discoveries of the Renaissance--the telescopes and mathematical calculations that introduced the heliocentric solar system and explained the visible phases and eclipses of the moon. Turning to the twentieth century, Scott recounts in some detail the history of great leap in knowledge following the 1959 Luna 2 rocket sent to impact on the moon by the USSR and the Apollo flights and landings,  and the scientists and astronauts who made it all possible.

The author devotes several chapters to the discoveries which returned moon rocks and dust have yielded, revealing much about Earth's history and indeed the history of known space. Special attention is given to the real treasure in attic, the "Genesis Rock," a specimen found by astronauts Scott and Irwin that was determined to be the oldest specimen, far older than any on Earth, at 4.5 billions years, the oldest known rock, a big clue to the mystery of the age of the solar system!

Ample illustrations, some full-spread, appear on each page, with Scott including ancient drawings and moon maps with black-and-white photos from Apollo and color photos from later missions. Text fact boxes, set apart with yellow and blue backgrounds, explain concepts included in the text, and Scott adds a substantial appendix, with a helpful glossary of technical terms, additional reading from selected books and web sites, bibliography, and a very usable index for students working on research papers or just following their own need to know more.

A well-organized and highly accessible text, well written to grab and hold the attention of middle readers and fire the imaginations of scientifically-minded students, this is a standout nonfiction book, a first purchase for school and public libraries or for the space-enthralled trekkie reader.

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