Great Image: The Solar System's Smaller Worlds

The image above recently posted by The Planetary Society is labeled "Every round object in the solar system under 10,000 kilometers in diameter, to scale." This impressive collection represents 2 planets, 18 or 19 moons, 1 or 2 asteroids, and 87 "trans-Neptunian" objects. 

You can see how the moons Ganymede and Titan outside Mercury, and our own Moon exceeds the size of Pluto.

The image below shows the objects we have already visited, including the recently explored Ceres and Pluto. We are making great progress in our explorations of the solar system. 

Image Credit: Montage by Emily Lakdawalla. Data from NASA / JPL, JHUAPL/SwRI, SSI, and UCLA / MPS / DLR / IDA, processed by Gordan Ugarkovic, Ted Stryk, Bjorn Jonsson, Roman Tkachenko, and Emily Lakdawalla.

A New Planet in Our Solar System?

The Orlando Sentinel recently reported on a distant object that appears to be in our solar system, yet its identity is unclear and it could be one of three things:

A TNO, or Trans-Neptunian Object (like Pluto), which is any body that orbits the sun beyond Neptune; a Super-Earth, meaning bigger than Earth but smaller than the gas giants like Saturn, Jupiter, Neptune or Uranus; or a very cool brown dwarf, which is what some scientists refer to as a failed star - bigger than Jupiter, but not big enough to produce the fusion necessary to become a star.

That is certainly a wide range of possibilities.  Scientists with the Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, and SE-439 92 Onsala, Sweden published a paper that stated:

The obvious question then is, what is its nature and why has it escaped earlier detection? Is it always too close to the binary? Is it too cold? In that case, i.e., at temperatures below a hundred Kelvin or so, the non-detection at shorter wavelengths, with e.g.WISE, would be reconcilable.

Good questions that other scientists will be very eager to answer.

Noteworthy Quote: Ancient Water in Your Tap

"Up to half the water on our planet is older than the solar system itself. Ancient water molecules assembled in the chilly confines of a gigantic gas cloud. That cloud spawned our sun and the planets that orbit it — and somehow those ancient water molecules survived the perils of the planetary birth process to end up in our oceans and, presumably, our bodies."

--  Ray Jayawardhana, a professor of physics and astronomy at York University in Toronto, in his New York Times article "Our Cosmic Selves."  He was highlighting the findings in an earlier study in Science, with the summary "The analysis suggests that all nascent planetary systems may have the same water resources that we did."