Showing posts from November, 2015

How the moon got its tilt—and Earth got its gold

Source:   By Sid Perkins, Science Excerpt: Miniplanets zooming through our early solar system passed close to our moon and tugged it into the strange, tilted orbit it has today, according to a new study. The findings solve a longstanding mystery and may also explain why Earth’s crust is unexpectedly rich in gold and platinum: When some of these small planets slammed into Earth, they delivered a payload of precious metals. Scientists have long debated the origin of the moon. The prevailing idea, first proposed decades ago, is that a Mars-sized planet collided with Earth, flinging material into space that then coalesced into our only natural satellite. According to current models of that collision, the ring of debris that eventually became the moon should have ended up in a plane tilted no more than 1° from the ecliptic, the plane in which Earth orbits the sun, says Kaveh Pahlevan, a planetary scientist at Université Côte d’Azur in Nice, France. But in fact, the moon’s orbital inclin

Mars to lose its largest moon, but gain a ring.

Source:   By Robert Sanders, UC Berkeley News. For GSS A Changing Cosmos chapter 7. Excerpt: Mars’ largest moon, Phobos, is slowly falling toward the planet, but rather than smash into the surface, it likely will be shredded and the pieces strewn about the planet in a ring like the rings encircling Saturn, Jupiter, Uranus and Neptune 10-20 million years... that will persist for anywhere from one million to 100 million years, according to two young earth scientists at the University of California, Berkeley. In a paper appearing online this week in Nature Geoscience, UC Berkeley postdoctoral fellow Benjamin Black and graduate student Tushar Mittal estimate the cohesiveness of Phobos and conclude that it is insufficient to resist the tidal forces that will pull it apart when it gets closer to Mars. Just as earth’s moon pulls on our planet in different directions, raising tides in the oceans, for example, so too Mars tugs differently on different parts of Phobos. As

The Dwarf Planet That Came in from the Cold—Maybe

Source:   By Ron Cowen, EoS, Earth & Space Science News, AGU Excerpt: ...The presence of ammonia-rich clay on much of the surface of Ceres suggests that this dwarf planet—the largest object in the asteroid belt—may have formed far out in the solar system, then wandered in....