Alright, this is the pre-requisite knowledge I mentioned so we can all be on the same page when discussing this issue. Apologies if this stuff seems
basic to you. I am sure some of it is new to people who might read this thread who are not well versed in astronomy or our Galaxy.
I hate boring stuff so I will try to make this post as interesting as possible by highlighting why this stuff is relevant to why we're all here:
"Aliens and UFOs".
So lets start with the basics before I move on to the Hill-Fish map.
Milky Way Galaxy Facts
The Milky Way contains over 200 billion stars, and enough dust and gas to make billions more.
The solar system lies about 30,000 light-years from the galactic center, and about 20 light-years above the plane of the galaxy.
More than half the stars (and by extension their planets) found in the Milky Way are older than the 4.5 billion year old sun.
That means, we're likely the kids or possibly even the babies of the Galaxy when it comes to intelligent life. In terms of our Galaxy we've barely
scratched the surface of what may be out there in terms of habitable planets. An analogy I like to make (which if you have kids you might be able to
relate to) is that we're in a baby crib (our planet), in our room (the solar system) which exists in a house (the small circle you see on the map of
the Milky Way below).
We''ve barely explored our house. Nevertheless within that house lay Zeta Reticuli and a whole host of interesting places we're only beginning to
Someone questioned whether the stars of Zeta Reticuli being 2-4 billion years older than sun would made any habitable planets around them
uninhabitable. That got me thinking now was the right time to give some basics of Stellar Classification and Stellar Evolution. Astronomy 101 level
As you'll see below, how long a star lives is based on its mass. The big hot stars live fast and die hard. Smaller stars than our sun live longer
The most common stars in the galaxy are red dwarfs, which are cool stars about a tenth the mass of the sun. Once thought unsuitable for potential
life-bearing planets because such bodies would have to be too close to meet the criteria, red dwarfs are now considered potential suspects. This is
due to the fact that advanced computer models show planet's tidally locked with atmospheres would still circulate heat and be habitable for our type
As a general rule in the universe the smaller something is, the more plentiful it is. Stars smaller than our Sun are more plentiful than stars like
our Sun or stars bigger than our Sun.
And as seen in the chart below. The biggest stars have shorter lives. However they are also rarer than our Sun.
The time period in which a star is stable is called the main sequence. Stars outside of this time period are either still forming or dying.
Our sun is in its main sequence right now and will remain so for about another 2-3 billion years After a stars main sequence the star can have
different deaths depending on its mass:
From hotest and most massive to the tiniest and coolest the average stars of our galaxy are: O, B, A, F, G, K, M.....and so on. (Brown Dwarfs and
White Dwarfs have their own special classes below M)
Each letter class is then subdivided based on temperature using a numeric digit with 0 being hottest and 9 being coolest. That diagonal band in the
middle are the stars we're most interested in from a life point of view.
In addition to this each stellar classification there is a further subdivisions based and luminosity and spectral characteristics which can tell a
This is called the Yerkes spectral classification. It is shown in Roman Numerals sometimes with another subdivision within it. The Yerkes spectral
class can show where a class of star is in its evolution and it runs from I (a hypergiant ready to go nova or supernova) down to VII (white dwarfs).
Stars in their main sequence are in the range of VI up to IV:
So what difference does all this make? What is our Sun? And what are the stars of Zeta Reticui and the other stars on the Hill-Fish star map?
That will be the subject of my next post. But before that I thought it might be a good idea to bring your attention to some things we know today about
the statistical likelihood of planets and specifically habitable planets like the Earth as a result of both the data Kepler gathered as well as ground
Kepler's main mission was to determine the relative frequency of different types of planets, with the grand prize finding another earth sized planet
in an earth like orbit in terms of a star's habitable (or "Goldilocks") zone.
What Kepler found was somewhat amazing. There are a fair amount of potentially habitable planets. The Habitable Planet Laboratory at Arecibo keeps
track of them and does further research into them.
Here is one of their graphics:
As you can see habitable planets larger than the Earth but smaller than the large planets of our own solar system seem to be more plentiful than
planets like the Earth. Kepler has found 12 of these habitable "Super Earths" or "Super Terrans" and found 35 more candidates (90% of Kepler's
candidates turn out to be real planets). However it only has found one Earth-sized candidate planet so far.
So one of the questions that some people often get asked about why aliens are always described as being short in stature and thin can now be
answered from a scientific perspective.
A planet 2 to 6 times the Earth's mass would have higher gravity. Anything which walked upright would by necessity be shorter and perhaps have more
efficient muscles than us on a lighter weight body.
It should be noted that Kepler is still sending back data which it took before its mission ended so researchers have not yet analysed everything it
has collected yet. the 3,500+ candidates on that chart are just from the data which has been sifted through, there are mountains of data that hasn't
even been sifted through yet for candidates. While other Earth-sized planets in habitable zones are probably within the data its like calling an
election: At this point we know that habitable Super Earths seem to be more likely than habitable Earth sized planets.
(Sidenote If you have good eyes and are into perhaps spotting a planet in the Kepler data there is a citizen science project I take part in called
Planet Hunters over at www.planethunters.org (part of Zooniverse). We've already found two planets which have been confirmed and tentatively named PH1
It should be noted that I have found that just about every star on the Hill-Fish map makes sense from an astrobiological point of view. Several of the
stars are in HabCat (the catalog 17,129 of the likeliest habitable stars in our local neighborhood put together by astronomers Jill Tarter and
Margaret Turnbull in 2003.) Others have been found to have habitable zone planets. BTW: I did cross correlation with HabCat and the Planetary
Habitability Lab while looking at the Hill-Fish map. Some stars beyond the map on the same lines also have habitable worlds.
Hope I didn't bore you.
I'm just a girl who is an astronomy student with an interest in UFO claims which may have verifiable information.
edit on 25-10-2013 by
JadeStar because: (no reason given)