The Milky Way galaxy is our home galaxy, which contains over 100 billion stars. It is a barred spiral galaxy approximately 120,000 light years in diameter. The Solar System is located in one of the galaxy's spiral arms, about 27,000 light years from the galactic core. In the future, it is expected that the Milky Way will collide and merge with the neighboring Andromeda galaxy in 3-4 billion years.
2. WHAT IS GALAXY ?????
A system of millions or billions of stars, together with gas
and dust, held together by gravitational attraction.
A galaxy is a gravitationally bound system of stars, stellar
remnants, interstellar gas, dust, and dark matter.
At the centre of many galaxies, there is a compact nucleus
that may sometimes be so bright that it overwhelms all the
normal radiation of the galaxy.
3. All in all, Hubble reveals an estimated 100 billion
galaxies in the universe or so, but this number is
likely to increase to about 200 billion as telescope
technology in space improves.
Most galaxies are 1,000 (3.086*10^16 Km) to 100,000
(3.086*10^19 Km) parsecs in diameter and are
usually separated by distances on the order of
millions of parsecs.
4. MILKY WAY GALAXY
Our Solar system is located at the outer regions
of a spiral galaxy named ‘Milky Way’. The
nearest neighbouring galaxy is the Andromeda
galaxy (M31).
The Milky Way Galaxy is an immense and very
interesting place. Not only does it measure
some 100000–120000 light-years in diameter, it
is home to our planet.
5. MILKY WAY GALAXY
The Milky Way Galaxy is our home galaxy in the
universe.
Its name "milky" is derived from its appearance
as a dim glowing band arching across the night
sky whose individual stars cannot be
distinguished by the naked eye.
6. MILKY WAY GALAXY
If you could travel outside the galaxy and look
down on it from above, you’d see that the Milky
Way is a barred spiral galaxy measuring about
120,000 light-years across and about 1,000
light-years thick.
For the longest time, the Milky Way was
thought to have 4 spiral arms, but newer
surveys have determined that it actually seems
to just have 2 spiral arms, called Scutum–
Centaurus and Carina–Sagittarius.
7. MILKY WAY GALAXY
The spiral arms are formed from density waves
that orbit around the Milky Way. As these
density waves move through an area, they
compress the gas and dust, leading to a period
of active star formation for the region.
However, the existence of these arms has
been determined from observing parts of the
Milky Way – as well as other galaxies in our
universe – and are not the result of seeing our
galaxy as a whole.
8. MILKY WAY GALAXY
Astronomers had long suspected the Milky Way
was made up of stars, but it wasn’t proven until
1610,
when Galileo Galilei turned his rudimentary
telescope towards the heavens and resolved
individual stars in the band across the sky. With
the help of telescopes, astronomers realized
that there were many, many more stars in the
sky, and that all of the ones that we can see are
a part of the Milky Way.
9. MILKY WAY GALAXY
The Milky Way looks brightest toward the
galactic center, in the direction of Sagittarius.
The fact that the Milky Way divides the night sky
into two roughly equal hemispheres indicates
that the Solar System lies near the galactic
plane.
The Milky Way has a relatively low surface
brightness due to the gases and dust that fills
the galactic disk.
10. MILKY WAY GALAXY
It is further believed that our galaxy formed
through the collisions of smaller galaxies, early
in the Universe.
These mergers are still going on, and the Milky
Way is expected to collide with the Andromeda
galaxy in 3-4 billion years.
The two galaxies will combine to form a giant
elliptical galaxy, and their super-massive black
holes might even merge.
11. MILKY WAY GALAXY
The Milky Way and Andromeda are part of a
larger collection of galaxies known as the Local
Group.
And these are contained within an even larger
region called the Virgo Super cluster – a mass
concentration of galaxies that contains at least
100 galaxy groups and clusters within its
diameter of 33 mega parsecs (110 million light-
years).
12. MILKY WAY GALAXY
That prevents us from seeing the bright galactic
center or from observing clearly what is on the
other side of it.
Our Sun is located in the Orion Arm, a region of
space in between the two major arms of the
Milky Way, and about 27,000 light years from the
galactic core.
At the heart of the Milky Way is a super-massive
black hole, just like all of the other galaxies,
known as Sagittarius A*.
13. MILKY WAY GALAXY
Our Sun takes about 240 million years to orbit the
Milky Way once, in what is known as a galactic year
(or cosmic year).
Just imagine, the last time the Sun was at this
region of the galaxy, dinosaurs roamed the Earth,
and the Sun has only made an estimated 18-20 trips
around in its entire life.
By this reckoning, the birth of our Sun took place
18.4 galactic years ago, and the Universe itself was
created approximately 61 galactic years ago.
14. MILKY WAY GALAXY
The Milky Way, like all galaxies, is surrounded
by a vast halo of dark matter, which accounts
for some 90% of its mass..
Nobody knows precisely what dark matter is,
but its mass has been inferred by observations
of how fast the galaxy rotates and other general
behaviors.
More importantly, it is believed that this mass
helps keep the galaxy from tearing itself apart
as it rotates.
15. MILKY WAY GALAXY
You might be amazed to know that dung beetles
actually navigate at night using the Milky Way.
If you’ve never seen the Milky Way with your
own eyes, you should take the chance when
you can. Go to a place with nice dark skies, free
from light pollution, and look up and appreciate
the Milky Way. And be sure to wave hello to all
the neighboring stars who share our galaxy with
us.
16. MILKY WAY GALAXY
You might be amazed to know that dung beetles
actually navigate at night using the Milky Way.
If you’ve never seen the Milky Way with your
own eyes, you should take the chance when
you can. Go to a place with nice dark skies, free
from light pollution, and look up and appreciate
the Milky Way. And be sure to wave hello to all
the neighboring stars who share our galaxy with
us.
17. MILKY WAY GALAXY
In truth, all pictures that depict our galaxy are
either artist’s renditions or pictures of other
spiral galaxies.
Until recently, it was very difficult for scientists
to gauge what the Milky Way looks like, mainly
because we’re embedded inside it.
If you had never been outside of your own
house, you wouldn’t know what it looked like
from outside. But you’d get a sense by looking
at the interior and comparing it to other houses
in the neighborhood.
