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.

The Search for Habitable Planets Expands

It is amazing that Star Trek in the 1960s and Cosmos on the 1970s speculated about distant planets, and here we are today actually studying thousands of newly discovered planets, searching for moons around these planets, and even planning to analyze the atmospheres on the planets themselves. We may not have flying cars as promised, but we are starting to see those distant worlds we predicted which I believe is far more fascinating.

Last month, NPR had a story on the search for moons around approximately 1,000 distant planets by astronomer David Kipping at Columbia University. He believes gaseous planets similar to Jupiter and Saturn may have habitable moons where life is possible. We know our solar system has such moons, such as Europa and Enceladus, that we have yet to adequately explore for signs of life. So we have plenty of work to do here at home as well. 

Another NPR story this month discussed three nearby planets that circle a red star. Only 40 light years away, the Earth-size planets may offer a habitable environment for life. And using the Hubble Space Telescope, astronomers hope to be able to learn about the atmospheres of these planets as sunlight filters though them, while the upcoming James Webb Space Telescope will be able to provide details on the chemical composition of the atmosphere. More reasons to be excited about new space investments.

The search can only get more interesting as our technology improves and our curiosity grows. Whether in our solar system or far beyond, there is so much to study and understand. 

Above Image: Top row, left to right, is Titan, Earth's Moon, Europa, and Encelasus. Bottom row, left to right, Callisto, Charon, Ariel, and Io.

Bottom Image: Artist's rendering of the three distant planets around a red star. ESO/M. Kornmesser/Nature