Sky & Telescope August 2011 Print Issue
When scientists measured the ages of rocks returned by the Apollo program, they made the startling discovery that most of the Moon's craters formed in a single 100-million-year burst about 3.9 billion years ago – an event now called the Late Heavy Bombardment. No doubt Earth experienced the same barrage, though almost all the evidence has been destroyed by our planet's active geology and weather. Scientists have puzzled for years what could have caused the Late Heavy Bombardment. Was it just the tail end of the solar system's formative period? Did a collision between two giant asteroids shower the inner solar system with a rain of fragments?
In the August 2011 issue, contributing editor Emily Lakdawalla explains how a new theory, known as the Nice Model (after the city in southern France) might explain the Late Heavy Bombardment as well as several other mysteries of the solar system.
Moving from our own solar system to others, Brandon Tingley recounts the astonishing history of exoplanet discoveries starting in 1855 – meticulous scientific studies "proving" the existence of planets that turned out to be illusory on closer scrutiny. The first true exoplanet discovery didn't come until 1992, but even after that, a trickle of false discoveries has continued to the present day.
Do you want to make scientific discoveries of your own? One technique that could help you greatly is spectroscopy. This immensely powerful tool created the field of astrophysics more than a century ago, and ever since it has stayed almost entirely within the domain of professional astronomers. But amateurs are increasingly horning in on the action. Amateur spectroscopist Tom Fields explains how new tools and techniques have made amateur spectroscopy easier and more affordable than ever. Amateurs with fairly simple equipment can now measure the redshifts of quasars and study the atmospheres of planets.
Read also about all the other exciting equipment announced at the 20th annual Northeast Astronomy Forum. And explore the Moon, solar system, and deep sky with our usual complement of great observing information.