Ive seen this posted a couple of times and there seems to be a misconception regarding what Super Earth means. A bit of a sensationalist title, if you ask me. The term super-earth means a large terrestrial planet. If it has a heavy iron core and lots of rock, like the Earth does, then yes. If its half ice like Titan, then not necessarily. The gravitational acceleration on the surface of a planet with constant density (an idealization) is proportional to both the density and radius of the planet. The rotational rate of a planet doesnt have any relationship to its mass. The rotational rate would be a function of the speed of rotation (really, the angular momentum) of the material that formed the planet in the first place. Also, if the planet suffered collisions, these collision can change the planets rate of rotation. For example, Venus not only has a very slow rotation, but it rotates retrograde, i.e. opposite the way Earth rotates on its axis. One likely theory is that something very large collided with Venus in its early history, and the collision sent Venus spinning in the other direction! The dwarf planet in the article is orbiting about 2.5xNeptunes distance from the Sun. In other words, its way the hell out there, and so its likely frozen. Calling it Super Earth has nothing to do with habitability but is rather saying that its a rocky planet as opposed to a Gas Giant (like Jupiter etc). Me too friend. Heres the paper via Nature, which comes with a heavy price tag, but if youre affiliated with a University then they might have a school-wide subscription that can be accessed by using a schools computer. nature/nature/journal/v507/n7493/full/nature13156.html I suppose because of the thicker atmosphere hypothesis they cannot call it Super Venus. Venus atmosphere is primarily carbon dioxide, whereas theyre proposing that super-Earths would have hydrogen-helium atmospheres. A mini-Neptune would be more accurate if were talking about similarity to known planets, but thats beside the point. Again, super here doesnt mean bigger version of. It just means bigger/more massive. Planetary nomenclature is messy. So to sum it up, we discovered a new dwarf planet that orbits way far out in the solar system, farther than any of the planets. This new object, along with another object, Sedna, are thought to be a part of the Oort Cloud. The Oort Cloud is like the asteroid belt, only its really far from the Sun and isnt a ring around the Sun (it makes a hollow sphere, hence the name Cloud instead of belt). The shape of these two bodies orbits are similar and appear to be like certain asteroids in the solar system; they form resonances where they can have an orbit that crosses a planets orbit without ever hitting it. I personally think that these two bodies having similar orbits is simply a coincidence, and once we discover more Oort Cloud objects we will see that there is no Planet X.
Posted on: Sun, 30 Mar 2014 19:38:35 +0000
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