Universe vs. Galaxy
The Universe is far too large for most of us to comprehend. There are 3 trillion galaxies in the observable universe and it keeps expanding (as does our ability to observe). Our galaxy is minuscule by comparison but it is still huge at 100,000 light years across. The closest neighbor to our solar system is Andromeda, only 2 ½ light years distant. It is estimated that the Milky Way has between 100 and 400 billion solar systems. Using the midpoint of 250 billion and the estimated number of earthlike planets per solar system at 40% (based on what we have seen) puts the potential planets with life at 100 billion. If only 1% of them have life and of that number, only 1% have intelligent life that still leaves 10 million planets that could provide alien visitors. Forget the universe our galaxy has plenty of potential for intelligent life.
Article by Ashley Yeager
February 23, 2017, at 11:08 am
Astronomers have just identified a nearby solar system hosting seven Earth-sized planets. Most intriguing: Three planets that orbit its central star — known as TRAPPIST-1 — may even be within a habitable zone. That means they fall within a region that could support life as we know it. As such, these newfound worlds are good sites to focus a search for alien life.
TRAPPIST-1’s big planetary family also hints that many more cousins of Earth may exist than astronomers had thought.
“It’s rather stunning that the system has so many Earth-sized planets,” says Drake Deming. He’s an astronomer at the University of Maryland in College Park. It seems like every stable spot where a planet could be, there is an Earth-sized one. And that, he adds, “bodes well for finding habitable planets.”
Astrophysicist Michaël Gillon works at the University of Liège in Belgium. He was part of a team that last year announced they had found three Earth-sized planets around TRAPPIST-1. This dwarf star is only about the size of Jupiter. It’s also much cooler than the sun. And it’s a relative neighbor to Earth, a mere 39 light-years away in the constellation Aquarius.
Follow-up observations with the Spitzer Space Telescope and additional telescopes on the ground now show that what first appeared to be a third planet is actually a quartet of Earth-sized ones. Three of these may be habitable.
If those planets have Earthlike atmospheres, their surfaces may even host oceans of liquid water. Or at least that’s what Gillon and his colleagues reported online on February 22 in Nature. Their data also offer signs of a seventh, outermost planet.