Hot! Planets, Planets Everywhere

While you may not know it, scientists have discovered hundreds of planets across the galaxy. Take a short tour to some of the more interesting ones.

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What if I were to ask you, “how many planets are there?” Would you stop and think, “OK, this is a trick question. Pluto doesn’t count, right?” Would you then confidently say, “eight?” Well, obviously your Very Educated Mother didn’t do a good job. Prepare to feel stupid. There are actually over 800 planets that we know about, and thousands of planetary candidates. See, there is a trick: these planets are actually not circling our Sun, but other stars strewn about the galaxy. They are known as extrasolar planets or exoplanets, and they are varied and pretty incredible. In this space, I figured I would outline some of the more interesting planets that have been found thus far. And forgive me for not explaining the myriad methods used to detect these planets, but if you are interested, here is a link.


51 Pegasi b (Bellerophon)


In 1995, the first extrasolar planet was found orbiting around a Sun-like star 50 light-years away in the constellation Pegasus called 51 Pegasi. Yep, that friggin’ long ago and you never even heard of it! Due to the incredibly creative naming system the IAU has devised, the planet is known as 51 Pegasi b, though it is informally called as Bellerophon. This was big news at the time, and frankly, it still should be. I find it remarkable that we can find planets around other stars and so should you. Bellerophon is what is termed a “hot Jupiter” since it is a gas giant, like our system’s most massive planet, but it is so close to its parent star that it only takes four days to orbit. This close-in orbit makes it extremely hot. Like between 1,832 and 3,632 degrees Fahrenheit hot. Like it would rain iron hot. And it is also tidally locked, meaning it always shows the same side of its surface to the star (like the Moon does with Earth). 51 Peg b is truly a hellish place.


HD 209458 b (Osiris)


HD 209458 b, or, Osiris, is one of the most well-studied extrasolar planets. Discovered in 1999, it is a really interesting world. It has an atmosphere containing hydrogen, oxygen, and carbon. Unfortunately, Osiris orbits so close to its star that the intense heat is literally evaporating the atmosphere away. You can’t make this stuff up. Based on all its weirdness, it is a favorite of scientists (and me). In fact, an image of what sunset on Osiris would look like was created recently. It is pretty cool; check it out.


Alpha Centauri B b


Discovered just a few months ago, this planet is the closest to Earth yet found. It is located only about 4.37 light-years away, which is really close, cosmically speaking. It is also the least massive planet found so far, about 1.13 times the mass of Earth. Unfortunately, it is much too close to its parent star to be suitable for our kind of life, and most believe it is a “lava world.” Something odd about this planet is that the Alpha Centauri system is a binary star system. So, it has two Suns, even though it only orbits one of them. The planet’s proximity to Earth makes it a prime candidate for an interstellar probe mission. And there may be other, possibly habitable planets in this system we haven’t found yet. Stay tuned.




This planet is really, really far away. Located near the center of our galaxy, at a distance of roughly 21,000 light-years, this easy to pronounce world is probably about five times as massive as Earth. It is really notable because it was discovered using gravitational lensing, a technique theorized by Einstein.




This world, located about 22,000 light-years away, in the galactic bulge (feel free to laugh…I did), is the fastest planet ever found. It whips around its star so fast that its year is only ten hours long. Scientists estimate its size based on the fact that if it were any smaller than 1.6 times the size of Jupiter, its star would tear it apart.


Gliese 1214 b


Located only about 40 light-years away, this planet is theorized to be hot and humid. A large amount of its mass is from water, whether it be in liquid or gaseous form. While it may not harbor life, the odd temperatures and pressures could result in “hot ice” or “superfluid water.” That would be pretty boss.


HD 189733b


It may seem crazy, but the atmosphere of this world has been detected and analyzed. It contains methane, which has been witnessed glowing, most likely due to aurora activity. It also contains water vapor and carbon dioxide. Those are some of the gases found in our own atmosphere. The methane is particularly exciting, since it can be an indication of life. Cross your fingers until we get there. It is only 63 light-years away.




Boy, this one just rolls off the tongue, huh? It is definitely a unique place. It is a planet, about 100 light-years from Earth, orbiting…nothing. That’s right, it is a planet without a star. It just floats on through the cosmos, unencumbered by any gravitational object. Weird, right? The thought is that this planet was ejected from a regular solar system by some sort of gravitational problem. Scientists believe this happens more than we would think, and there could be billions of these “orphaned” worlds out there. And we thought we were alone…


Gliese 581 System


Since this whole system is intriguing, I figured I would lump all of them together. By “them,” I mean Gliese 581 c, d, e, & g. While the existence of the last of these remains in dispute, the others have been confirmed and are somewhat Earth-like. This is exciting since finding an Earth analog planet is kind of the Holy Grail. Gliese 581 g represents the best chance of having liquid water on its surface. If it exists, that is.


Kepler-22 b


We might be able to live here one day, even though it is 600 light-years away (so remember, pack a book). Although it lies closer to its star than Earth does, its star is less luminous, so it is actually within the habitable zone. This is quite the important fact. This means liquid water can probably exist on its surface, and therefore, life. If the planet has the same type of atmospheric greenhouse effect as Earth, the surface temperature would be a balmy 72 degrees Fahrenheit. Its discovery leads scientists to believe that finding a truly Earth-like planet is just a matter of time.
So, obviously this was a very limited rundown of some of the planetary highlights. There may soon be an incredible addition, however. Scientists believe that this may be the year we find an Earth-like planet. If found, it would be impossible to get there any time soon, but we could aim our radio telescopes in its direction to see if we pick anything up.

Oh, and I realize the sheer volume of planets makes it impossible to name them creatively, but come on. These names are atrocious. They should come up with some kind of contest. If you could rename these planets, what would you call them? (And keep it clean…jerks) I actually like the mythology theme, but no need to keep it in the Roman and Greek family. After all, we have Haumea and Makemake in our own Solar system.

Oh, you didn’t know about those either?

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Some cool links to find out more:

Planet Quest
Extrasolar Planets Encyclopedia
Habitable Exoplanets Catalog
Kepler Mission

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Jerry Galante is a corporate cataloging librarian. He has a BA in History and a Master’s in Library Science and really wishes we would just land an ice drill on Europa already. If you enjoyed this post, you should check out Jerry’s previous offering, “If the World Ended, How Would It Happen?”


Jerry Galante


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