Stan Deyo (Link) - The New York Times - John Noble Wilford (January 30, 1983)
Something out there beyond the farthest reaches of the known solar system seems to be tugging at Uranus and Neptune. Some gravitational force keeps perturbing the two giant planets, causing irregularities in their orbits. The force suggests a presence far away and unseen, a large object that may be the long-sought Planet X.
Evidence assembled in recent years has led several groups of astronomers to renew the search for the 10th planet. They are devoting more time to visual observations with the 200-inch telescope at Mount Palomar in California. They are tracking two Pioneer spacecraft, now approaching the orbit of distant Pluto, to see if variations in their trajectories provide clues to the source of the mysterious force. And they are hoping that a satellite-borne telescope launched last week will detect heat “signatures” from the planet, or whatever it is out there.
The Infrared Astronomical Satellite was boosted into a 560-mile-high polar orbit Tuesday night from Vandenberg Air Force Base, CA. It represents an $80-million venture by the United States, Britain and the Netherlands. In the next six or seven months, the telescope is expected to conduct a wide-ranging survey of nearly all the sky, detecting sources not of ordinary light, but of infrared radiation, which is invisible to the human eye and largely absorbed by the atmosphere. Scientists thus hope that the new telescope will chart thousands or infrared-emitting objects that have gone undetected – stars, interstellar clouds, asteroids and, with any luck, the object that pulls at Uranus and Neptune.