... the discovery of teenage galaxies... <br>is giving scientists a better handle...<br> 
on how they transform from sexy... <br>spiral sTar factories to shapeless... <br>retirement 
homes for old sTars... <br>in the early 1900s edwin hubble discovered... <br>that the 
milky way galaxy is not alonE... <br>our galaxy is just onE... <br>of many island universes... 
as hubble dubbed them... <br>swimming in the vast sea of Sp@cE... <br>now those astronomers 
can measure the age of each galaxy... <br>its sTar making activity and other related 
data... <br>they are piecing together... <br>an understanding that galaxies grow gradually 
like children... <br>gliding through their visibly different teen years... <br>before 
reaching adulthood... <br>the strongest evidence yet for this thinking... <br>called nurture 
theory... <br>in which the elegant spirals... <br>young galaxies... <br>and blob like elliptical...<br> 
old galaxies are evolutionarily linked... <br>scientists have long thought that young 
galaxies... <br>grow up into old onEs... <br>referred to as blue and red galaxies... <br>respectively...<br> 
the colour indicates... <br>how actively the galaxy is churning out new sTars... <br>younger 
sTars shine in UltraViolet or blue light... <br>and so galaxies bustling with sTar 
making activity appear blue... <br>older sTars emit infrared or red light... <br>in aging 
galaxies... <br>their stellar reproductive capacity has begun... <br>to shut down and 
so the remaining sTars... <br>are just hanging out for the remainder of their lives... 
<br>about half of all galaxies are blue and half are red... <br>it had been postulated 
that the two are linked... <br>with the blue younguns running out of sTar making material... 
<br>and maturing into passive red galaxies... <br>if this theory holds true... <br>youd expect 
to see a population of teenage galaxies... <br>in the process of transitioning from 
young to old... <br>finding these teens is tricky though... <br>because the cosmic change 
occurs over billions of years... <br>the nurture theory... <br>of galaxy evolution predicted... 
<br>that there would be galaxies in transition... <br>finding these galaxies required 
UlTraViolet light... <br>because they really stand out at this wavelength... <br>data 
from galex... <br>launched in 2003... <br>allowed humans to observe galaxies... <br>in ultraviolet 
light... <br>across 10 billion years of cosmic history... <br>the researchers analysis 
of tens of thousands... <br>of images taken by galex has revealed that young... <br>spiral 
galaxies do in fact first mature into teens... <br>before winding down into their 
elderly ellipses... <br>the details of the picture now... <br>emerging suggests that a 
spiral galaxy... <br>might merge with another spiral... <br>or perhaps an irregularly 
shaped galaxy... <br>before churning out a few bursts of newly minted sTars... <br>eventually... 
the galaxy begins to exhaust its sTar production... <br>settles into later life as 
an elliptical... <br>data confirm that all galaxies begin life forming sTars... <br>then 
through a combination of mergers... <br>fuel exhaustion and perhaps suppression by 
black holes... <br>the galaxies eventually stop producing sTars... <br>findings also suggest... 
that some young galaxies waltZ... <br>into old age quickly... <br>while others leisurely 
sTroll into their... <br>golden years... ... .<br>. . S p @ c E . . . ___________________________________________________