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| Andromeda Galaxy is 50% bigger than our Milky Way. |
You must have heard
about the collision of asteroid with the
planet and aware of the destruction that can be caused by such
an event. But there is one bigger cosmic event that is the collision of our Milky Way Galaxy with the Andromeda
Galaxy. These two galaxies will merge to form a new
galaxy in future. This was the common process of formation of new galaxies
after the big bang.
Before talking about
collision let us first look at these galaxies. Milky Way is a spiral galaxy
consists of nearly 100 billion stars and has diameter of nearly 100,000 light
years. Our sun is present in the middle of the spiral arm and
revolves around galaxy within the spiral disk.
Our galaxy is part
of local group of galaxies which has nearly 50 big or small galaxies. Andromeda
Galaxy is our neighbouring galaxy which is spiral in shape with diameter 50 %
more than the Milky Way. Andromeda Galaxy is present at the distance of 2.5 million light years from us.
In early years of 20th century Hubble and many other
astronomers observed that the galaxies are moving away from each other which
lead to the expanding universe then why this Andromeda Galaxy is moving towards us.
As we know that
these two galaxies are part of local group, so they are bound by the
gravitational interaction which is bringing them close to each other. Andromeda
galaxy is moving towards Milky Way with the velocity of 250000 miles/h.
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The Milky Way and Andromeda are moving toward each other
under the inexorable pull of gravity. Also shown is a smaller galaxy,
Triangulum, which may be part of the smash up. (Credit: NASA; ESA; A. Feild and
R. van der Marel, STScI)
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"After nearly a
century of speculation about the future destiny of Andromeda and our Milky Way,
we at last have a clear picture of how events will unfold over the coming
billions of years," says Sangmo Tony Sohn of the Space Telescope Science
Institute (STScI) in Baltimore.
"Our findings
are statistically consistent with a head-on collision between the Andromeda
galaxy and our Milky Way galaxy," adds Roeland van der Marel of the STScI.
Next question
arises, when will these two galaxies collide?
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This series of photo illustrations shows the predicted
merger between the Milky Way and Andromeda as seen from the Earth. The first
frame is the present day; the last frame is 7 billion years from now. (Source:
NASA, ESA, Z, Levay and R. van der Marel (STScl), T. Hallas, and A. Mellinger )
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An important
question is still there, what will happen to galaxies during collision? Will it
harm the Earth?
When two galaxies will merge, there centers which have big black holes tries to engulf each other but the other revolving stars in the spiral arms will not be harmed due to vast empty space between them. Star collision will be rare in spiral arms. The transformation of two centers into one center is not so peaceful because due to gravity the pressure increases on the clouds and material of center which results in the high temperature and formation of new stars. Supernovae and X- ray emission will be there. The rate of generation of new stars is as high as 100 times of normal rate. The center of new deformed galaxy will be glowing for millions for years due high formation new stars and finally with the end of raw material the center will become dark and fade.
When two galaxies will merge, there centers which have big black holes tries to engulf each other but the other revolving stars in the spiral arms will not be harmed due to vast empty space between them. Star collision will be rare in spiral arms. The transformation of two centers into one center is not so peaceful because due to gravity the pressure increases on the clouds and material of center which results in the high temperature and formation of new stars. Supernovae and X- ray emission will be there. The rate of generation of new stars is as high as 100 times of normal rate. The center of new deformed galaxy will be glowing for millions for years due high formation new stars and finally with the end of raw material the center will become dark and fade.
All this
rearrangement will not affect our sun and solar
system. Our sun along with its solar system will be thrown into new region of galaxy. There are two
possibilities, one is sun will be thrown towards the edge of galaxies where we
will have very less stars in sky and our sky will be much darker than today. Now
sun will revolve around newly formed galaxy. The other possibility is slightly
dangerous which will include throwing of sun towards the center where X- ray emission may harm us. But
we do not need to worry about that because in these 4 billion years, sun will run out of fuel and grow in size which will result
in destruction of life due to heat.
Anyway there is rare
possibility that this collision will harm solar system or Earth. For
example, according to these scientists:
It is likely the sun will be flung into a new region of our galaxy, but our Earth and solar
system are in no danger of being destroyed.
References: