12
Nov 10

Structure and Formation of the Lunar Farside Highlands

A bulge of elevated topography on the farside of the Moon - known as the lunar farside highlands - has defied explanation for decades. But a new study led by researchers at the University of California, Santa Cruz, shows that the highlands may be the result of tidal forces acting early in the Moon's history when its solid outer crust floated on an ocean of liquid rock. Since the Apollo 15 laser altimeter experiment, scientists have known that a region of the lunar far side highlands is the highest place on the Moon. Additionally, the far side has only highlands and no maria.


Image credit: NASA/JPL

This research was published on the issue 12, November 2010, of Science magazine by Ian Garrick-Bethell, Francis Nimmo and Mark A. Wieczorek. The group of international scientists found that perhaps the tidal processes of Jupiter’s icy moon, Europa, can provide a clue. Like Europa’s icy crust that sits over an ocean of liquid water, the Moon’s crust once floated on a sub-surface ocean of liquid rock. So, could the same gravitational forces from Jupiter that influence Europa also apply to the Earth’s influence on the early Moon? Garrick-Bethell and his team found that the shape of the Moon’s bulge can be calculated by looking at the variations in tidal heating as the ancient lunar crust was being torn away from the underlying ocean of liquid magma.

Links:

Science 12, November 2010

Related News:
Universe Today
Moon Daily

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12
Nov 10

Detailed Dark Matter Map Yields Clues to Galaxy Cluster Growth

Credit:Hubble Site News Release STScI-2010-37


Hubble Helps Astronomers Map Dark Matter in Abell 1689. Image credit: HST

Astronomers using NASA's Hubble Space Telescope received a boost from a cosmic magnifying glass to construct one of the sharpest maps of dark matter in the universe. They used Hubble's Advanced Camera for Surveys to chart the invisible matter in the massive galaxy cluster Abell 1689, located 2.2 billion light-years away. The cluster contains about 1,000 galaxies and trillions of stars. Dark matter is an invisible form of matter that accounts for most of the universe's mass. Hubble cannot see the dark matter directly. Astronomers inferred its location by analyzing the effect of gravitational lensing, where light from galaxies behind Abell 1689 is distorted by intervening matter within the cluster.

Researchers used the observed positions of 135 lensed images of 42 background galaxies to calculate the location and amount of dark matter in the cluster. They superimposed a map of these inferred dark matter concentrations, tinted blue, on a Hubble image of the cluster. The new dark matter observations may yield new insights into the role of dark energy in the universe's early formative years. (read more)

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