Showing posts from June, 2015

How Did the Moon Get Its Shape?

Source:   By Catherine Minnehan , EOS—publication of AGU Excerpts: Scientists find a solution to a 200-year-old problem: syncing the prominent bulges on the Moon with our natural satellite's origins. Scientists have known for hundreds of years that the Moon’s rotational and tidal bulges are much larger than expected. The deformation is thought to be a remnant from when the Moon orbited much closer to Earth than it does today. The problem is, the bulges we see require an unusual eccentric orbit—one that scientists do not think the Moon ever had. Keane and Matsuyama solved this problem by discovering a new component to the Moon’s global figure. The Moon is not perfectly spherical because strong forces pull it in different directions. There are two main forces: bulging at the equator due to lunar rotation and bulging on the nearside and farside due to tidal forces between the Earth and the Moon. The observed lunar deformation is much larger than scientists would exp

Exoplanets: Worlds Without End

Source:   Scientific American eBook description: Section 1, “Exo-Search,” sets the stage and outlines how astronomers are looking for new worlds: the various techniques, how they’ve improved to date and plans for upcoming missions. Sections 2 through 5 analyze the discoveries, often both controversial and strange. Section 3 focuses on the race to find other Earth-like planets. With excitement at an all-time high, author Ron Cowen cautions against publishing too quickly out of optimism. In “Noisy Stars May Create Phantom Planets,” Cowen describes how stellar activity can mimic the signs of tiny exoplanets. Section 4 takes on the real oddballs. They may be remnants of gas giants whose atmospheres were stripped away, as in the piece "The Bones of Giants," or have alien chemistries. Some trace their course around white dwarfs, the results of a second generation of planets forming around old stars. Section 5 asks if there’s life out there. In "Anybody Home?&q

NASA’s Hubble Finds Pluto’s Moons Tumbling in Absolute Chaos

Source:   NASA Release 15-111. Excerpt: If you lived on one of Pluto’s moons, you might have a hard time determining when, or from which direction, the sun will rise each day. Comprehensive analysis of data from NASA’s Hubble Space Telescope shows that two of Pluto’s moons, Nix and Hydra, wobble unpredictably. “Hubble has provided a new view of Pluto and its moons revealing a cosmic dance with a chaotic rhythm,” said John Grunsfeld, associate administrator of NASA’s Science Mission Directorate in Washington. ...The moons wobble because they’re embedded in a gravitational field that shifts constantly. This shift is created by the double planet system of Pluto and Charon as they whirl about each other. Pluto and Charon are called a double planet because they share a common center of gravity located in the space between the bodies. Their variable gravitational field sends the smaller moons tumbling erratically. The effect is strengthened by the football-like, rather than spherical, sh