SUNSET: 
“Planet X” May Have Left Our Solar System Billions of Years Ago
A new understanding of far-off worlds in the outer solar system suggests that if "Planet X" ever existed, it has long since left the vicinity.
60-second Astro News: Most Distant Solar System Object & Saturn's Disappearing Rings
In astronomy news this week, astronomers announce the most distant solar system object discovered to date and estimate the limited lifetime of Saturn's spectacular rings.
New Wrinkles in the Search for “Planet X”
Are astronomers being misled about a possible ninth planet by the quirky alignment of orbits that they’re finding in the distant Kuiper Belt?
Top 12 Astronomy News Stories of 2016
From the discovery of gravitational waves to the building evidence that a massive planet could exist beyond Pluto, it has been a thrilling year for astronomy research. We recap.
Orbital Path Podcast: In Search of Planet 9
Astronomers are debating the existence of a big planet beyond the orbits of Pluto and Neptune. Dr. Michelle Thaller talks with planetary scientists Scott Shepard and Mike Brown about when we'll discover it.
Making the Case for "Planet Nine"
Does a massive, extremely distant planet orbit the Sun? A new analysis of distant solar-system orbits argues that it should exist.
New Object Offers Hint of "Planet X"
Astronomers have kicked around the idea of a distant "Planet X" for decades. But the recent discovery of 2012 VP<sub>113</sub>, located in an orbital "no man's land" roughly twice as far away as Pluto, has stoked the possibility that it really exists.
