[gary]

In a 31 July 2017 article at the Institute of Electrical and Electronics
Engineers (IEEE) web site, W. Wayt Gibbs reports on the continued
speculation of a Neptune-sized planet beyond the orbit of Pluto and
the use of supercomputers to attempt to model where it might be so
as telescopes would know where to point.

Greg Laughlin, an astronomer at Yale University, says, “Our best estimate for its current position and brightness put it about 950 times farther than Earth from the sun.” As faint as the tiniest moons of Pluto, Planet Nine would be barely two pixels wide on the Hubble Space Telescope’s camera. Searchers could easily miss it among random speckles of sensor noise and the twinkling of distant and variable stars.

Huge telescopes on Earth have been scanning the skies for months now. Brown and Batygin have been observing on Japan’s Subaru telescope on Mauna Kea—as have veteran minor-planet hunters Chad Trujillo of Northern Arizona University and Scott Sheppard of the Carnegie Institution for Science⁠—to exploit that observatory’s giant mirror (8.2 meters across) and its 3-metric-ton, 870-megapixel camera. Meanwhile other astronomers, both professional and amateur, are digging through archives of images in hopes of finding this needle in a hayfield.

In addition to the groups working on Subaru, Sheppard and Trujillo are leading searches in the high desert of Chile, in case the planet is easier to see from the Southern Hemisphere. There, both the 570-megapixel Dark Energy Camera (DECam) on the 4-meter Blanco telescope and the 6.5-meter Magellan telescopes are contributing to the hunt.

Any of them could get lucky. But the smart money is on software, either to deliver the quarry or reveal it to be an illusion. Simulations running on supercomputers and in the cloud are modeling billions of years of celestial mechanics to pin down Planet Nine’s likeliest path. Engineers at the Jet Propulsion Laboratory, in Pasadena, have been analyzing telemetry from the Cassini spacecraft for clues to the current position of the putative planet within its enormous orbit. And an ambitious pair of graduate students is preparing to deploy machine-learning software on a petaflop-scale Cray XC40 supercomputer. Their strategy aims to cleverly combine multiple images in which Planet Nine is hidden within the noise to yield one image in which it shines unmistakably.

Meanwhile, at the Southwest Research Institute in Colorado, David Nesvorný has been modifying his far more detailed models of the formation of the Kuiper Belt from the early days of the solar system to see what happens when he plugs in a ninth planet. The simulation, built on a symplectic code known as SyMBA, starts with a million virtual TNOs as they might have existed in the nascent solar system. The system computes 4.5 billion years of evolution and then compares the outcome to what astronomers see today. Each run takes more than five weeks to complete on 500 CPU cores of NASA’s Pleiades supercomputer.

Article here :-
http://spectrum.ieee.org/aerospace/s...g-beyond-pluto