Earth has been traveling through the universe for almost 4.5 billion years. For a vast majority of that time, it has supported life. Researchers approximate that living organisms first arose on our Pale Blue Dot around 3.5 billion years ago (however other approximations propose that life may have started as far back as 3.9 billion years ago).
In this time, single cells arose. They thrived in water for a time but, ever so gradually, they developed into more complicated life forms and left Earth’s murky waters for land. Over the next few billion years, this land-based life split out into trees, and birds, and people like you and me.
Earth 600 million years ago Image Credit: Walter Myers
Eventually, we know that life in our cosmos is at least 3 billion years old; though, it could be far, far older.
In 2003, Hubble directed its lenses at a sun-like star, and it witnessed a truly ancient planet. The world is around 13 billion years old, making it one of the oldest planets in the known cosmos. At more than twice the age of the Earth, it would have made just a billion years after the Big Bang.
Researchers found it at the center of a globular star cluster called M4, which is just around 5,600 light-years from Earth in the constellation Sagittarius. So, is it likely that life as we know it arose on this world ages before it did on Earth?
Planet history via Hubble
Well, that is a little improbable, as the planet is unluckily close to a pulsar. Pulsars, if you are not aware, are a kind of highly magnetized neutron star. These stars produce tremendously energetic beams of electromagnetic radiation, which would have coursed across the planet and in effect rendered it sterile.
Moreover, the planet is a gas giant, meaning that it probably lacks a solid surface like what we have on Earth. Furthermore, at 2.5 times the mass of Jupiter, by the time you get to its hypothetical solid core, the pressure would make it completely impossible for life as we know it to survive. If that’s not sufficient, since it formed so early in our universe’s history, researchers believe that it perhaps does not have much heavier elements, like carbon and oxygen, as these were only created in plenty later (once the first stars blasted in fiery supernova explosions.)
Of course, carbon and oxygen are two of the necessary constituents for our kind of life, making this planet a relatively poor candidate.
The star Kepler-444 is now branded to host five Earth-sized planets in very squeezed orbits. Image via Tiago Campante/Peter Devine
Though, there is still hope for ancient life. When our Sun and planets were born, the Kepler-444 system was by now older than our solar system is now. And particularly, the planets that this system has are Earth-sized (as opposed to massive gas giants). Actually, it has 5 planets that are similar in size to Earth.
The finding was publicized January 27, 2015 in the Astrophysical Journal, and it used observations made by NASA’s Kepler spacecraft over a period of four years.
In the release, researchers proclaimed that Kepler-444 formed some 11.2 billion years ago, and that the planets formed around the same time, making these worlds the oldest Earth-sized planets ever discovered. Of the discovery, Daniel Huber, from the University of Syndey in Australia and an author on the paper, said:
We have never witnessed anything like this. It is such an old star and the large number of small planets makes it very extraordinary. It is astonishing that such an ancient system of terrestrial-sized planets formed when the cosmos was just starting out, at a fifth its present age. Kepler-444 is two-and-a-half times older than our solar system, which is only a youthful 4.5 billion years old.
This tells us that planets this size has formed for most of the history of the cosmos and we are much better located to comprehend precisely when this began happening. So, Could these worlds host life as we know it? Well, again, possibly not. This is because the planets orbit their parent star in just 10 days. And a short orbital period means that the planets are very near to the star. Eventually, at less than one-tenth the Earth’s distance from the Sun, liquid water cannot exist, and on top of this, the worlds have very high levels of radiation – making them rather uninhabitable for us.
But then how can life probably be much older than the 3 billion years that was mentioned in relation to Earth?
Well, these are just a small sample of the planets that exist in our cosmos. We have not found anywhere near even just a fraction of the alien worlds that are out there. As such, it is completely probable that other (possibly even older) worlds exist that could have had environments promising to life.
…though maybe not life as we know it (but whoever said that the universe only consists of life as we know it?).