Space is a bizarre place with its alien planets, mysterious moons, and strange phenomena that are
so out of this world they elude explanation. Astronomers have estimated that there are
approximately 10,000 stars in our universe for every grain of sand there is on earth.
However as with most rules there are exceptions and one star in our universe is notably different
from the others to the extent that we can almost certainly call it the weirdest star
ever discovered welcome the Factnomenal and today we will take a look at this unstable enigma Mira
meet Mira which is also known as omicron seti a red giant star that's estimated
to be between 200 and 400 light years from the sun in the constellation Settis which is
named after the sea monster in greek mythology which both Perseus and Heracles needed to slay
while Oseti which has been latinized to Omicron Ceti is the star's bayer designation
he was also named Mira by polish astronomer Johannes Hevelius in his 1662 publication
Historiola Mirae Stele. Mira is an extremely appropriate name for this bizarre star
as it translates from latin as wonderful or astonishing the international astronomical union
organized a working group on star names in order to catalog and standardize proper names for stars
the group's first bulletin in July of 2016 included a table for the first two batches of
names they'd approved and the list included Mira for the star making it absolutely official Mira is
a binary stellar system consisting of Mira a which is a variable red giant along with mirror b which
is its white dwarf companion what makes Mira a so interesting is that it is a pulsating variable
star and it was the first non-supernova variable star discovered with the possible exception of
Algol it is therefore a prototype of the class of pulsating stars known as Mira variables
Mira has been known to us since ancient times but its unique nature only became apparent in
the 16th century a german pastor an amateur astronomer by the name of David FAbricius
a man who regularly corresponded with the more famous and renowned astronomer Johannes Kepler
discovered that the star's brightness changed periodically every 11 months and not just by
a small amount these changes were huge or perhaps more appropriately they were
astronomical in their magnitude as a general rule mira isn't a difficult object to observe when the
time and conditions are right at peak brightness it shines at a healthy second or third magnitude
which is more than bright enough for it to be observed by the naked eye
conveniently it was almost peak brightness in august 1596 when Fabricius observed it
from his home in Germany near the border of what we now know as the Netherlands a
few months later when he attempted to view it again he was shocked as it seemingly vanished
where did it go Mira's disappearing act initially led Fabricius to believe that the star was a nova
a rare but amazing type of star that brightens very suddenly then disappears from view
permanently however to his astonishment he saw it brighten again nearly 13 years later and in 1609
he knew he discovered a new class of celestial objects known as long-term variable stars this
variable star was viewed on many further occasions throughout the 17th and 18th centuries and those
subsequent observations revealed that it varied in brightness with a period of around 333 days
those variations ranged from about magnitude 2 or 3 down to a magnitude of around 10.0 which is a
factor of about fifteen hundred what does all this mean it means that it is the largest variation of
stellar brightness in anything other than the more cataclysmic variables such as novae or supernovae
the depth and periods of variability of Mira are not precisely regular like they are in the case of
the aforementioned variable star Algo for example but the periodic variability was clear enough and
impressive enough for Johannes Hebelius to give it its wonderful and astonishing name
why does it act this way but exactly what is it that causes Mira's astonishing variability
well the shortest and simplest answer is that it's currently experiencing a phase of its evolution
whereby the pull of gravity and the burning of hydrogen fuel in shells around its core
are contesting with each other which causes regular pulsations with the transparency of
hydrogen ions in the outer atmosphere acting as a sort of on off switch to start each cycle afresh
gravity pulls the outer layers of the star inward for a few months which increases the temperature
of the outer layers and increases the opacity of ionized hydrogen the increased heat in radiation
pressure builds up resulting in the expansion of the star the ions then grow transparent and cool
resulting in the outer layers falling back towards the star's core think of it as though
it's a weight on the end of a spring bobbing up and down within the earth's gravitational field
the spring pulls up the earth pulls down and that process is repeated over and over during
said process a star is at its brightest when it nears its smallest radius when it's at its hottest
a dysfunctional family as we briefly touched upon earlier in the video there is now a whole class of
long-term variable stars called Mira variables of which Mira itself is obviously the most well-known
kaisigni arcarene are hydrae and arleonus are amongst a fairly long list of others whose
variable brightness are also visible to the naked eye stars of this nature
all boast a deep red coloring and tend to vary over many months by several magnitudes
essentially they're all red giant stars that are incredibly advanced in terms of their life cycles
having run out of hydrogen fuel in their cores a long long time ago
as a result the internal parts have compressed and heated to burn heavier elements like helium
and their red coloring is further enhanced when in some cases they pull out enriched material
from their cores as millions and millions of years pass a Mira variable will generally
blow off its outer layer and turn into an aesthetically incredible planetary nebula
like the ring nebula and the dumbbell nebula until its core finally placates as a burned out ember
that we call a white dwarf interestingly our own sun will also go through such a phase in around 5
billion years time so the process will certainly have implications closer to home eventually
that essentially means that when we observe Mira we're actually getting a sneak peek at the distant
future of the very star we orbit as it begins its inevitable demise if Mira is something that
sounds interesting to you then why not observe the variability of it for yourself it can be
found in the neck of the Cetus constellation and is visible from around September through January
for northern observers it's just over the southern horizon and it's almost directly overhead for
those in the southern hemisphere don't despair if you can find mirror without the aid of specialist
equipment it probably just means it's at a point in its cycle where it's dimmed the truth is the
majority of its existence is spent being invisible to the naked eye and if the conditions make it so
it's actually possible for two or three years to go by without people being able to see it
regardless Mira really is the sight to behold when it becomes visible to the naked eye in the space
of a couple of weeks if you'd like to check out how bright Mira currently is as well as how bright
countless other stars like it are and to estimate when it will next brighten to naked eye visibility
simply head to the website of the American association of variable star observers
and use the light curve generator app just enter the star's name the start and end date
of interest you want to know about and click on the plot data button it's definitely worth a look
so what did you think about Mira have you ever seen a Mira variable in the night sky
tell us in the comments if you enjoyed the video please be sure to leave it a like and subscribe to
our channel for more great videos just like this and as always thanks for watching Factnomenal