Pluto shares its part of the solar system with more than 1500 other icy worlds that we know about and countless ones that have, so far, evaded our detection. The shapes of their orbits are clues to a tumultuous history that hinges on the motion of Neptune.
Neptune formed in a location much closer to the Sun than it is now, but migrated outward from the Sun over time. As it moved, it herded and scattered the objects in the Kuiper belt. Neptune trapped some of them -- like Pluto, Orcus, Haumea, and Makemake -- in orbital resonances, locked in motion synchronized to the giant planet's. Others -- like Eris and 2007 OR10 -- it scattered to extremely elliptical or highly inclined orbits. Others, it tossed inward into the solar system, to bombard the other planets or to orbit among them as Trojans, centaurs, or irregular moons. And one -- Triton -- it captured as its own moon. There is a belt of objects so far unaffected by Neptune's motion -- like Quaoar -- called the cold classical belt. Finally, there is Sedna, whose orbit is so distant from Neptune's that it may represent the first-discovered member of a wholly unexplored part of the solar system.
Eris, Orcus, Haumea, Makemake, 2007 OR10, Quaoar, Sedna, and Triton are the largest worlds in Pluto's neighborhood, and the little that we have learned to far about their surfaces proves that each is unique. More than a hundred others are probably large enough to be called "dwarf planets." And there may yet be even larger, Mars or even Earth-sized worlds beyond these, awaiting discovery.
There is only one mission that has ever been launched to study Pluto: New Horizons.
Recent Blog Articles About Pluto and Its Neighbors
In the span of a few days, Pluto and Charon have turned from spots into worlds. The latest images from New Horizons are showing Pluto and Charon to have unique faces, distinct from any other icy worlds in the solar system.
This year we achieve the first exploration of these curious but fascinating objects. Paul Schenk explains what we may learn about them.
When New Horizons wakes up for the final time on Dec. 6, scientists will spend six weeks preparing for the start of the spacecraft's Pluto encounter.
Joseph O’Rourke summarizes a recently submitted paper on tectonic activity on Pluto after the Charon-forming impact.
Earlier today I wrote a post about how to calculate the position of a body in space from its orbital elements. I'm trying to get a big-picture view of what's going on in trans-Neptunian space.
Last week, I posted an explainer on why Hubble's images of galaxies show so much more detail than its images of Pluto. Then I set you all a homework problem: when will New Horizons be able to see Pluto better than Hubble does? Here's the answer.
Three months ago, I posted an article explaining what to expect during the flyby. This is a revised version of the same post, with some errors corrected, the expected sizes of Nix and Hydra updated, and times of press briefings added.
As New Horizons approaches Pluto, when will the images get good? In this explainer, I tell you what images will be coming down from Pluto, when. Mark your calendars!
What's that in the distance? A binary star? Those are two little round worlds dancing in circles, whirling around a point in space located between the two of them. It's Pluto and Charon, clearly separated by New Horizons' camera.
It has been a difficult wait for new New Horizons images, but the wait is almost over; Alan Stern announced at today's Outer Planets Advisory Group meeting that image downlink will resume September 5. In the meantime, a few space fans are making the most of the small amount of data that has been returned to date.
An attempt to corral the discussion of the IAU planet definition in one place on planetary.org, so that we may be free to actually discuss Kuiper belt observations and scientific results on posts elsewhere on this site.
It's looking likelier that there is an undiscovered planet orbiting beyond the Kuiper belt. If it's there, it's roughly 10 times the mass of Earth (or about half the mass of Neptune), likely never gets closer to the Sun than about 100 AU, and takes more than 10,000 years to orbit the Sun.
Space rarely makes a strong showing in national elections, despite the major state of transition NASA finds itself in today.
Help us catalog and source statements made by candidates referring to civil space issues.