The Theory of Nothing

What do extraterrestrial planets look like?

What do extraterrestrial planets look like?

This is a subject near and dear to my heart. The fact that astronomers have detected extraterrestrial planets, or exoplanets, is exciting because it may lead to the discovery of intelligent aliens.

An exoplanet is by definition a planet orbiting a star other than our sun, and the surprising thing is that they come in all sorts of varieties and arrangements out there in our galaxy.
I've already discussed how astronomers find exoplanets. In this essay I want to discuss what these planets are like, and I have many to discuss. The Kepler space telescope has detected thousands of them. Believe it or not but there's a catalog of exoplanets at Exoplanet.eu (as of Aug 15 there are 1946 planets in their catalog). This gives the planet's physical data and the star it orbits and its physical data. These exoplanets vary from smaller rocky planets to huge gas giants. Some are extremely cold and some are hotter than you know where.

I think that it would be more interesting to discuss the possible habitable exoplanets that have been discovered. There are eight of them (as of July 2015), according to Wiki: Kepler-438b, Kepler-442b, Kepler-440b, Kepler-186f, Kepler-62f, Kepler-62e, Kepler-296e and Kepler-296f.

For example: Kepler-62e is a super-Earth planet orbiting in the habitable zone of Kepler-62, which is a K2V-class star (a red dwarf star that's smaller than our sun). It has five known companion planets, two of which are rocky. Kepler-62e has a radius 1.6 times Earth's and is thought to have considerable amounts of liquid water on its surface. Kepler-62f is another super-Earth with a radius 1.4 times that of Earth. Kepler-62 is a star that's around 1200 light years away.

Kepler-186f is an Earth sized planet orbiting the M-class red dwarf star Kepler-186 that's 492 light years away. The planet has a radius that's 1.1 time that of Earth, which means it's nearly the same size. Fortunately, this planet is not tidally locked to the star, but it could rotate much slower than Earth.  A day could be a week.

Kepler-438b is another near Earth sized exoplanet (radius is 1.12 times Earth's) orbiting a red dwarf star Kepler-438 that's 470 light years away. It's a rocky planet with the possibility of liquid water on its surface.

Kepler-452b is the latest discovered Earth-like exoplanet that orbits a star much like our sun. The planet is not exactly an Earth twin. It's 1.6 times larger and it orbits a star that's a bit brighter than our sun. All we know is that it's a rocky planet in the habitable zone.

The bad news about these Kepler habitable exoplanets is that SETI hasn't detected any radio signals from their respective solar systems. Not much is known about the chemical composition of these exoplanets' atmospheres. But, that's about to change.

In the next three to five years the UK's new satellite called Tinkle will be launched and this device will have sensitive spectrometers linked to a telescope that will be able to determine the composition of these planet's atmospheres. This is important because if water vapor is found along with oxygen we may be able to say that these exoplanets definitely have life as we know it.

Astronomers have found gas giants much larger than Jupiter and even a Saturn-like planet with a massive ring structure. They have found gas giants that are orbiting very close to their stars. Many of these exoplanets have been discovered around binary, ternary and even quadruple star systems. As of this year (2015), 5400 possible exoplanets have been discovered, but only 1827 of them have been confirmed.

There is a lot of disagreement about whether life will be found on these exoplanets, but with time I believe that the arguments will be settled. It's just a matter of time.

However, I might add here that even though there are supposedly a lot (billions) of planets in the Milky Way galaxy that are Earth-like and possibly contain life, the presence of intelligent life requires much more. One of the reasons that we are here is because Earth orbits a single dwarf star that's not in the main part of an arm of our galaxy. Our sun has been around for 4.7 billion years and Earth has been here for 4.5 billion years. After life formed here (or was brought here by asteroids from Mars according to the Panspermia theory) it spent at least 2 billion years as one-celled creatures in the oceans. When multi-celled creatures evolved, they were around for about a billion years before something complicated evolved. I might add here that multi-celled creatures only evolved because of oxygen being in the atmosphere. The primordial Earth had no oxygen until cyanobacteria created it by photosynthesis. Cyanobacteria are believed to have evolved because of a genetic accident, which is the moving force of evolution. Oxygen provided the energy for creatures to evolve more efficient metabolisms, and it's oxygen that fueled the next phases of evolution, which involved fish and amphibians. Fish have been around 500 million years. The dinosaurs ruled the Earth for around 250 million years. Mammals have been around a 100 million years, but modern humans have been here only 200 thousand years, a mere drop in the bucket of time. What this means is that our planet, and our star, had to be stable for billions of years for us to evolve into an intelligent species. Near the center of the galaxy, radiation is too intense for life to evolve and mature. Radiation from supernovae in the form of gamma ray bursts would preclude life maturing. Thus, planets in the denser parts of the galaxy's arms are not safe and neither is it in the outer edges of the galaxy. The Earth just happened to be in the Goldie Locks section of the galaxy. This means that intelligent life may be very rare because space is violent and very dangerous to life. We just don't know yet what's out there, but we're about to find out.

Thanks for reading.