Category Archives: planets

astronomy news, dwarf planets, Plutoid

You’re Not Just a Dwarf Planet…

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You’re a Plutoid

After two years of what must have been grueling discussion, the International Astronomical Union has decided that things that are like Pluto (which used to be defined as a planet) are now going to be called “Plutoids” as long as they orbit at or beyond the orbit of Neptune. Dwarf planets (as a small-body definition), as you may recall, was an outcome of the 2006 IAU meeting, when it was decided that we needed a new category for worlds that aren’t quite planets, but are bigger than asteroids. The name plutoid for a specific subset of dwarf planets was proposed by the members of the IAU Committee on Small Body Nomenclature (CSBN), accepted by the Board of Division III, by the IAU Working Group for Planetary System Nomenclature (WGPSN) and approved by the IAU Executive Committee at its recent meeting in Oslo, Norway.

Two Plutoids: Pluto (shown with its companion Charon) and Eris (with Dysnomia)

So, what are the characteristics of Plutoids? They have to be celestial bodies in orbit around the Sun at a distance greater than that of Neptune. They must have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium (near-spherical) shape. And, they haven’t cleared the neighborhood (of debris) around their orbit. So, Pluto and Eris fit this definition, and scientists expect more small worlds like them to be found as astronomers keep finding them out the great beyond.

By this definition, the dwarf planet Ceres is NOT a Plutoid, but it’s still a dwarf planet. This is because its orbit is within the asteroid belt and not transneptunian.

atmosphere, climate change, Earth, global warming

Earth is Where It’s At

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And It’s All We Have… For Now

https://i0.wp.com/nssdc.gsfc.nasa.gov/image/planetary/earth/gal_east-pacific.jpg?resize=474%2C356

Sooner or later, everybody who is interested in space and astronomy gets a look at our planet from “the outside.”  This image, from the Galileo spacecraft during one of its swings around Earth, tells a pretty remarkable story. If you were an incoming alien vessel, you’d see evidence of water. The oceans tell that story, but so do the clouds because they’re made of water vapor. The land masses would tell you that there are places to land on this planet, but at this distance and resolution, you wouldn’t be able to make out plants and animals… or humans and their cities.

If your alien ship had special sensors, it could use spectral analysis to dissect the gases in the atmosphere that blankets the planet. You would find oxygen, nitrogen, plus trace amounts of other gases.  Oh, and carbon dioxide. That’s a biggie. Carbon dioxide (you sometimes see it as CO2) is a by-product of living and geological processed. And, it’s the principal component of the greenhouse gases that we are pumping into our atmosphere from energy generation (driving cars, making electricity, powering manufacturing, etc.). The more greenhouse gases we load into the atmosphere, the warmer our climate is getting. And this is having an effect that future spacecraft will see (and we will have to live with).

As you can see from this picture, our atmosphere looks pretty thin when compared to the vastness of space and the size of our own planet. In fact, if you look at other planetary atmospheres in the solar system, you find them to be thick and heavy (Venus, the gas giants), or thin and possibly even fragile (Mars, Earth, some of the smaller moons of the outer solar system). What we learn about atmospheres is important, since our own planet has the only one that we know of that has harbored (and possibly even helped begin) life.  That makes what we’re doing to it with carbon dioxide a pretty major “experiment.”