Friday, January 2, 2015

Exoplanets: the year in review


Time now again for Science Friday.

Space brought us a bevy of new exoplanets in the past year. Each of them has its own unique properties just as can be said of the planets of our own solar system. I like looking at just what each of these strange, new worlds brings and that's just what this article at Space.com does. You can read the full article at the link, but I'll give you a quick rundown here. Plus, you'll also get my thoughts on the subject and let's face it, who doesn't want that?

Kepler-186f was discovered by, as the name suggests, the Kepler space telescope. The planet is 490 light years from Earth and is only just slightly larger than our planet. It's not just size that we have in common with 186f but its location in its own solar system. The planet orbits its home star within what is termed "the habitable zone" for life as we understand it. It might even have liquid water but more evidence needs to be acquired before that claim may be solidified.

Gliese 832c is only 16 light years from Earth but is over five times our size. Opinions vary as to the planet's composition, including visions of a dense, greenhouse environment such as that of Venus or perhaps a habitable one such as our own.

Kepler-10c has been dubbed "the Godzilla of Earths." It has even warranted the creation of its own classification: mega-Earth. It is 17 times the size of our world and what is unusual about that is that such a massive planet would normally be a gas giant, such as Jupiter or Saturn. This one appears to be rocky. Then again it's 590 light years away so it's all anybody's guess.  On the other hand a terrestrial planet of this size shouldn't be all that shocking as gas planets have also been located in smaller statures.

We also have a lead on what looks like the first exomoon. Using the technique known as gravitational microlensing, which examines how a foreground object's gravity warps light from a star as it passes our line of sight, a team of astronomers noticed an object that could be one of two things: a free-moving exoplanet with a rocky exomoon or a small star that hosts a planet 18 times more massive than Earth. Sadly, such observances are random and solid confirmation of an exomoon remains elusive.

Kapetyn b is 13 light years from Earth and is estimated at being over 11.5 billion years old. By way of comparison, Earth is estimated at just under 4.6 billion years old (I don't care what the fundies say) and the universe is thought to be 13.8 billion years old (ditto). This is tantalizing for Kapetyn is in the habitable zone of its star. Therefore if life arose on that planet, it has had a very long time to evolve.

For those of us who always wanted to watch a dual sunset as Luke did on Tatooine, there is the planet OGLE-2013-BLG-0341LBb. Geez, they really have to start coming up with easier names for these things besides catalog entry numbers. Anyway, it orbits one star of a binary star system. It's probably too cold to support life as we know it, but any living thing that is there can get the sunset/sunrise of sci-fi dreams.

These discoveries are very telling. Given the sheer number of exoplanets we have found, it would seem to indicate that planet-less stars are the extreme rarity and not the norm. Just about every star observable in the night sky (save for the "stars" that are actually planets in our own solar system) should have at least one planet orbiting it. The means by which our solar system formed is likely a standard template for the rest of the universe, meaning the system is a rather common one. Well, unless you have a binary star or triple star or a cosmological event that altered the shape of things which could always happen.

Yesterday, I made several predictions for the New Year. I am going to toss another bold one onto the pile. In 2015, we will either find a new exoplanet that has...or determine one we've already discovered has...liquid water and an oxygen-rich atmosphere. Then all bets are off, ladies and gentlemen.

Here's to hoping for another remunerative year in exoplanet discovery.



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