Andromeda – Our Nearest Spiral Galaxy

The spiral galaxy of Andromeda
Andromeda Galaxy. 220,000 light years across, containing 10 trillion stars

What was the subject of the popular heated debate between ace astronomers, Heber Curtis and Harlow Shapley? – The Andromeda galaxy!

Back in 1920, Shapley believed that the Pinwheel and the Andromeda galaxies were actually nebulae found in the Milky Way. Curtis believed that this wasn’t the case, based on the argument that the Andromeda galaxy is on a multi-million light-year distance from our Milky Way. It was later established through the work of Henrietta Leavitt, Edwin Hubble, and others that Curtis indeed was right.

Over the years, a lot astronomers have researched Andromeda with some of the findings listed below..

Once a Nebula?

Long before the actual expanse of the universe was realized, the rim of the Milky Way was considered to be the boundary of outer space. Within those boundaries the fuzzy blur visible in the sky (the Andromeda) was believed to be a cluster of cosmic dust clouds and forming stars. The galaxy was originally named the Great Andromeda Nebula until the powerful telescopes of the 20th century proved otherwise.  

It Can Be Seen From Earth

This mammoth, dazzling galaxy is at least at a 2.5 million light year distance away from us. However, if you find a clear night sky (the pollution levels need to be down too) you can see the galaxy with the naked eye. It would appear as a scattered haze. Grab a pair of good binoculars and you can clearly witness the central region of the galaxy. A large powerful telescope will leave you in awe of the spectacular view of Andromeda.

It’s Gigantic

The galaxy has a diameter stretched across almost 220,000 light years. A colossal structure that seems longer that the full moon at night and is actually 2.5 times longer in length than the entire Milky Way. It is farther than any other star visible from earth, yet it can still be seen with the naked eye. 

It is believed that the Milky Way is the most immense body in the Local Group (a galactic group based on more than 54 galaxies), but the Andromeda takes the cake when it comes to being more voluminous. It contains trillions of stars, twice as much as the ones in our galaxy. It was the Spritzer Space Telescope that made this observation.

We’ve Known It for a Lifetime

The Andromeda galaxy being clearly visible in the night sky has been constantly scrutinized, observed, and studied by astronomers for multiple decades. The galaxy spawned about 10 billion years ago when several smaller protogalaxies merged together. About some 8 billion years ago it collided head on with another galaxy that led to the formation of the giant that is Andromeda today.

Now here’s the fun part.  Andromeda is moving towards our galaxy. And it’s not just moving – it’s actually on a collision course! 

Let that sink in. Andromeda and the Milky Way are both moving towards each other at a speed of 120 kilometers per second. But here’s the catch: at this rate it’ll take around 4 billion years for the galaxies to collide!

 

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