November 2010 Northern Rockies Skies

October 28, 2010

A monthly look at the night skies of the northern Rocky Mountains, written by astronomers Ron Canterna, University of Wyoming; Jay Norris, Challis Idaho Observatory; and Daryl Macomb, Boise State University

November premieres our most beautiful winter constellations, which are rising after 9 p.m.
An hour after sunset on the southwestern horizon, the Milky Way rises to the zenith accompanied the summer triangle, which will be lost for another season. Overhead are the two prominent constellations, Pegasus and Cassiopeia. Pegasus, the winged horse, is slightly to the south of the Milky Way, and is recognized by its famous Great Square.

The queen Cassiopeia, a regular to us northern observers, is easily recognized by its stretched out W or M star pattern. A few hours later rising prominently in the east, a definite sign of the arrival of winter, is Taurus the bull followed by Orion the hunter.

Taurus, this majestic constellation, forms a prominent "V" in the sky and is the location of the nearest cluster of stars, the Hyades. Aldebaran, the eye of the Bull ,is the bright orange star. Keep an eye out for these two constellations throughout the month.

This November you will have a fine opportunity to view Jupiter throughout most of the month. It is in the southeast right after sunset and sets around 3 a.m. About two hours before sunrise, look for Venus and Saturn on the eastern horizon. As in every November, the Leonid meteor shower will peak Nov. 17-18, with about 40 per hour. Look in the east in the constellation Leo but due to the full moon at this time the fainter meteors may be overlooked

November 2010 Interest: Space-Based Gravitational Wave Detectors
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Last month, we discussed terrestrial gravitational wave detectors, the most state-of-the-art being the LIGO experiment, comprising two facilities in Louisiana and on the Hanford Nuclear Reservation, Washington state. These terrestrial detectors are designed to search for relatively short wavelength gravitational waves. Their space-based counterpart is the Laser Interferometer Space Antenna. LISA is a NASA mission planned for launch in 2025.

Gravitational waves are envisioned as "ripples in space-time" -- analogous to waves produced on a water surface when disturbed by a passing boat-except the material vibrated by gravitational waves is not water, rather it is the postulated fabric of space-time. The movement of very massive objects creates these space-time waves. LISA should be able to detect mergers of binary supermassive black holes in distant galaxies and binary stellar-sized black holes in our own galaxy.

Both LISA and LIGO are designed detect the space-time disturbances, but in different wavelength ranges. LISA will be sensitive to wavelengths from 10 billion to 3 million kilometers-very long waves indeed. LIGO's wavelength range is much shorter, from 300,000 to 300 kilometers.

The LISA experiment will consist of three satellites in an equilateral triangle, with sides 5 million kilometers in length. The triad of satellites will orbit at the same distance from the Sun as Earth, but advanced along Earth's orbit by 50 million kilometers.

The passage of very long gravitational waves causes extremely small variations in the distances between the satellite pairs. Since the satellite distances will change due to other forces in the solar system -- planetary gravitational forces and the solar wind -- accurate knowledge of these forces is necessary. A pathfinder mission to demonstrate aspects of LISA's design is slated for 2013.

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