Exoplanets and then Habitable planets
1 Exoplanets
- An exoplanet ... or extrasolar planet is a planet outside the Solar System.
- The first evidence of an exoplanet was noted in 1917, but was not recognized as such.
- The first scientific detection of an exoplanet was in 1988; it was confirmed to be an exoplanet in 2012. The first confirmed detection occurred in 1992.
- As of 1 July 2019, there are 4,096 confirmed planets in 3,053 systems, with 664 systems having more than one planet.
- .......
- Some are so far out that it is difficult to tell whether they are gravitationally bound to the star.
- Almost all of the planets detected so far are within the Milky Way.
- Nonetheless, evidence suggests that extragalactic planets, exoplanets farther away in galaxies beyond the local Milky Way galaxy, may exist.
- The nearest exoplanet is Proxima Centauri b, located 4.2 light-years from Earth and orbiting Proxima Centauri, the closest star to the Sun.
much-edited source
Although we have seen the vast numbers of stars on other pages, and masses of exoplanets here, we must now look for
2 Habitable planets
People mentioned are not explored.
2.1
- At roughly 13.8 billion years old, the Universe might seem like it's been around for a long time, but a new study suggests that Earth is one of the first habitable planets to form - and we're probably too early to the party to get a chance to meet future alien civilisations.
- The research looked at data from the Hubble and Kepler space telescopes, and predicted that 92 percent of the Universe's habitable planets have yet to be born.
- And most won't form until after our Sun burns out in 6 billion years' time.
- It's kind of depressing to contemplate that, as a planet, we may have peaked way too soon.
- But another way to look at it is the fact that we're likely to be one of the only civilisations with the ability to look back at the birth of the Universe.
- "Any far-future civilisations that might arise will be largely clueless as to how or if the Universe began and evolved," explains the Space Telescope Science Institute in the US, which led the research. And that's a pretty humbling thought.
2.2
- But how many of these planets would exist in the habitable zone?
- Kipping was working with 330 exoplanets then discovered, with about thirty in the habitable zone of their host star, and so he suggested a fraction of 10 percent would be a safe estimate based on current knowledge.
- He then factors in a galactic habitable zone, assuming that one may exist and that any value he obtains will therefore be an underestimate if it does not.
- This takes the number of stars with habitable planets down to 5 percent, but still leaves him with 50 million habitable-zone exoplanets in the Milky Way.
- We can contrast that with Alan Boss’s prediction of ten billion habitable exoplanets in our galaxy and, of course, with Guo’s team, whose whopping 45.5 billion is the largest estimate I’ve ever seen.
3 The Goldilocks Zone here to be continued
4. Aliens are extinct