Earth has been wandering through space for about 4.5 billion years. She endures life most of this time. Scientists estimate that living organisms first appeared on our planet about 3.5 billion years ago (although according to other estimates, life may have appeared as early as 3.9 billion years ago).
At this time, individual cells arose. They thrived in the water for some time, and though slowly, they developed more complex life forms, and left the murky waters of the Earth for land. Over the next several billion years, this life branched out into trees, took off as birds, and became people like you and me.
So far, we know that life in our universe has existed for at least 3 billion years; however, she may be much, much older.
In 2003, the Hubble Space Telescope pointed its lenses at a sun-like star and saw a truly ancient planet.
This world was 13 billion years old, making it one of the oldest planets in the universe. Twice as old as Earth, this planet was formed just a billion years after the Big Bang.
Scientists have discovered it in the center of the globular star cluster M4, which is located just 5600 light years from Earth in the constellation Sagittarius. So, could life as we know it have formed on this planet many years before it formed on Earth?
Well, unlikely, since the planet is very close to the pulsar. Pulsars, as far as we know, are a highly magnetized neutron star. These stars emit extremely powerful energy beams of electromagnetic radiation that rolls around the planet and renders it sterile.
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In addition to this, the planet is a gas giant, which means it is unlikely to have a solid surface like we do on Earth. Moreover, given a mass 2.5 times that of Jupiter, by the time you reach this planet's hypothetical solid core, the pressure will nullify any chance of any life form surviving.
If that's not enough, scientists believe that due to the formation time in the Universe, this planet lacks heavy elements like carbon and oxygen, since their abundance appeared much later (when the first stars turned into the first supernovae).
Of course, carbon and oxygen are two essential ingredients for life, which means this planet will not be the best candidate for the development of life. But there is hope.
When our Sun and planets were born, the Kepler-444 system was already older than our solar system is now. In addition, there are five planets in this system, the sizes of which are similar to those of the earth.
The discovery was reported on January 27, 2015 by the Astrophysical Journal, and was made based on observations of the Kepler spacecraft over four years.
In the article, scientists reported that Kepler-444 was formed about 11.2 billion years ago, and the planets were formed at almost the same time, which makes these worlds the oldest terrestrial planets that we know. Daniel Huber of the University of Sydney Australia, author of the paper, said the following:
“We have never seen anything like it. Such an old star and a huge number of minor planets make the system special. It is amazing that such an ancient system of terrestrial planets was formed when the universe had just appeared, when the age was one-fifth of the current. Kepler-444 is two and a half times the age of our solar system, which is practically still a child - it is only 4.5 billion years old."
This tells us that planets of this size have been forming throughout most of the history of the universe, and we can practically understand when exactly this began.
Can these worlds have life? Again, most likely not. Because these planets orbit the parent star in just 10 days. The short orbital period means that the planets are very close to the star. At a distance of one tenth from the Earth to the Sun, liquid water can no longer exist. Add to this the high levels of radiation - these worlds will definitely be unusable for us.
Can you say that life just can't be older than 3 billion years?
We have considered only a small sample of the planets that exist in our universe. In reality, there are many more. We have not found or studied even a small fraction of the worlds that exist somewhere there. It is quite possible that there are worlds much older than ours, the conditions of residence on which allow life to exist. However, perhaps this life will be radically different from ours.