The Milky Way is a disk
that measures about 120,000 light years across, with a central bulge that has a
diameter of about 12,000 light years. However, the disk is not perfectly flat.
It is warped due to our neighboring galaxies, the Large and Small Magellanic
clouds. These two galaxies have been pulling on the matter in our galaxy like a
universal game of tug-of-war.
galaxy has over 200,000 stars:
The Milky Way is only a
medium sized galaxy with an estimated 200 billion stars. The largest galaxy we
know of is called IC 1101 and has over 100 trillion stars.
galaxy was made from other galaxies:
In order for the Milky Way
to achieve its current size and shape it has consumed other galaxies throughout
its history. Our galaxy is currently consuming the Canis Major Dwarf Galaxy by
adding the smaller galaxy’s stars to its own spiral.
is a black hole in the center:
Like most larger galaxies,
the Milky Way has a supermassive black hole at its center, called Sagittarius
A*. This black hole has an estimated diameter of 14 million miles, which does
not include the disk of mass being drawn into it. This outer disk has about
14.6 million times the mass of our Sun in what would be similar to the orbit of
galaxy has an invisible halo:
Our galaxy is made up of
about 90% dark matter, matter that cannot be seen, and about 10% “luminous
matter”, or matter that we can see with our eyes. This large quantity of dark
matter causes an invisible halo that has been demonstrated by simulations of
how the Milky Way spins. If the dark matter did not exist then the stars within
the Milky Way would orbit much slower than has been observed.
galaxy is really dusty and gassy:
About 10-15% of the Milky
Way’s visible matter is made of dust and gas, with the rest being stars. On a
clear night, the dusty ring of the Milky Way can be seen as a streak across the
can’t take pictures of it:
Since we are located about
26,000 light years from the Milky Way’s center we cannot take pictures of the
disk. Any representation that you have ever seen of our galaxy is either a
different spiral galaxy or what an artist thinks it might look like.
almost as old as the Universe itself:
Scientists estimate that
the Universe is about 13.7 billion years old and that the Milky Way is about
13.6 billion years old. Although the main parts of the galaxy were formed in
the early days of the Universe, the disk and the bulge did not fully form until
about 10-12 billion years ago.
part of the Virgo Supercluster, a group of galaxies within 150 million light
The Virgo Supercluster
contains at least 100 galaxy groups and clusters, and is about 110 million
light-years in diameter. A 2014 study shows that the Virgo Supercluster is only
one lobe of a greater supercluster called Laniakea.
10) Our galaxy is on the move:
Everything in space,
including the Milky Way, is moving. The Earth moves around the Sun, the Sun
moves in the Milky Way, and the Milky Way cruises through space. Cosmic
Microwave Background radiation, radiation left over