They now say in outer ridges of our galaxy there is planets 5 billion years older than Earth
Could it be that Jupiter and Saturn also came from elesewhere and were grabbed by our Sun's gravity well and are now here, protecting Earth from stream of comets?
There is actually no consensus that Juputer and Saturn are the same age as Earth. Only Earths age have been determined with any great accuracy.
Because 5 billion years of additional time is a long time, there may be multiple worlds in the Milky Way harboring alien life even more advanced than our own.
Astrobiologists think a planet
>needs to have certain features to support life: oxygen in its atmosphere,
something to shield organisms from dangerous radiation and liquid water, for a start. Although big land masses aren't strictly necessary for living things to emerge, Earth's history shows that they're important for life to thrive and exist for long periods of time.
So, if an exoplanet had continents before Earth, it follows that there might be older, more advanced life on that world.
This line of thought led Jane Greaves, an astronomer at Cardiff University astronomer in the U.K., to answer the question: When did the first continents appear on a planet in our galaxy? Turns out, two exoplanets' continents — and perhaps life — may have arisen four to five billion years before Earth's.
Continents form due to plate tectonics, the movement of plates of rock that float atop the molten innards of a planet. Heat from a planet's core keeps that magma from hardening and halting continents' movement. That heat comes from radioactive elements — like
and potassium-40 — in the planet's core, which give off energy as they decay.