This week, after setting our clocks back an hour and the night sky takes center stage
in our early evening hours in the northern hemisphere, we’re going to look at one of
the most distant objects that can be seen with the naked eye: the Triangulum Galaxy.
Rising in the east shortly after sunset, the constellation Triangulum appears.
The constellation itself is hard to find, because it consists of only a triangle and
we can make out many of those in our connect-the-dots patterns that make up the constellations.
The easiest way to find Triangulum is to look for the Great Square in the constellation
Pegasus.
I know, finding a square is also really easy to do, and there appear to be many of those
as well, but this one is very bright and sits relatively close to the distinctive constellation
of Cassiopeia.
So, after locating the Great Square of Pegasus, follow it down toward the horizon and past
Andromeda.
If you are out on a very dark night, you’ll see the Andromeda Galaxy in between Cassiopeia
and Andromeda.
The constellation Triangulum itself is an unremarkable, dim triangle but it is home
to a remarkable object: the Triangulum Galaxy or M33.
This galaxy is actually visible to the naked eye on very dark nights.
Like the Andromeda Galaxy, it appears as a faint smudge that is best viewed using your
peripheral vision, that’s the part of your eye that is most sensitive to very dim, greyscale
things.
The galaxy appears between the triangle and the bright star in Andromeda called Mirach
and you may have noticed it’s close proximity in the sky to the Andromeda Galaxy.
That’s because the Triangulum galaxy is a member of our local group of galaxies that
include Andromeda and the Milky Way.
In fact, the Triangulum galaxy is the third largest in our local group and many astronomers
think it is gravitationally bound to Andromeda.
It is a little farther away from us than the Andromeda Galaxy.
The Triangulum Galaxy is approximately three million light years from us, while Andromeda
is only 2.5 million light years away.
Here is an image of M33 taken with amateur equipment, and here is one taken from the
Very Large Telescope in South America which shows glowing red gas in the spiral arms.
This galaxy is sixty thousand light years across and contains some 40 billion stars.
By comparison, our galaxy, the Milky Way is home to over 400 billion stars.
If the Triangulum Galaxy is in fact linked with Andromeda, then we can expect this galaxy
to also take part in an amazing galactic collision in a little over two and a half billion years
between The Andromeda Galaxy, the Triangulum Galaxy and our own Milky Way Galaxy.
When this occurs, all three will be torn apart by gravitational tidal forces and will gradually
reform into a larger galaxy, perhaps producing one of the largest in the universe: a mighty
elliptical.
Well that’s it for now Space Fans, thank you all for listening and as always, Keep
Looking Up!