Milky Way Galaxy

Milky Way Galaxy

Till now, we read about two beautiful galaxies, Andromeda and Whirlpool; now let’s know some interesting things about our home galaxy - Milky Way (MW).

One funny aspect is that the thing got named long before knowing what it was. As you may already know, during a dark night, mostly away from urban lights, a white band is seen across the sky. Earlier, till end of 19th century, even scientists used to think all that we see is universe and every things (stars/clusters) is contained within our structure, later to be proven otherwise.

That milky band is actually part of the disk of our galaxy, it is mostly obscured by dust. We can NOT see our own galaxy completely for obvious reasons, though we know that it is a “Barred Spiral Galaxy”.

Apart from being our home, there is nothing special about MW, in terms of size, it has about ‘just’ 100 to 400 billion stars (compared to about 1 Trillion in Andromeda) and a diameter of only of about 1,00,000 (1 Lakh) light years (ly) compared to about 2.2 ly of Andromeda. I have given a comparison picture to show where MW actually stands and how tiny we are in the whole scheme of things.

MW will be merging with Andromeda in about 4 billion years to form a much larger elliptical galaxy.

While most of our galaxy is invisible to us, the Fermi Gamma-ray Space Telescope mission for detected a beautiful, awe inspiring phenomenon. It discovered two extremely large Gamma ray emission bulges/bubbles ‘above’ and ‘below’ the galactic center. These are formed due the super-massive black hole at the MW center that is devouring nearby stars at a high rate; while mass is eaten by the black hole, some radiation escapes to form these structures.

A Barred Spiral Galaxy (NGC 1300)

Artist's impression of Milky Way

Barred Spiral Galaxy (UGC 12158) that looks similar to Milky Way

Gamma ray emission bulges/bubbles formed by super-massive black hole at the center of Milky Way

MW compared to larger and largest galaxies

Photo Credits (Wikipedia/Wikimedia):

https://en.wikipedia.org/wiki/Phoenix_Cluster…

https://en.wikipedia.org/…/File:800_nasa_structure_renderin…

https://en.wikipedia.org/…/File:Artist%27s_impression_of_th…

https://en.wikipedia.org/wiki/File:UGC_12158.jpg

https://en.wikipedia.org/wiki/Barred_spiral_galaxy…

https://en.wikipedia.org/wiki/NGC_262

https://en.wikipedia.org/wiki/Andromeda_Galaxy

M51 - Whirlpool Galaxy

M51 - Whirlpool Galaxy

Couple of weeks back we got an introduction of how a galaxy looks like, with an extremely high resolution image (most detailed so far), of our nearest neighbor Andromeda galaxy - M31 (link to post in comments)

Today, I will write about some awe inspiring facts and share links of one of the most magnificent galaxy, Whirlpool Galaxy (aka Messier 51 or just M51); the picture tells the reason behind the naming.

M51 is the First galaxy to be classified as a ‘Spiral Galaxy’, at a distance of about 25 million light years and with the axis or rotation directly pointing towards us, giving a  ‘full face view’, is a well known and studied astronomical object. M51 has a companion, a small galaxy named 51b and is gravitationally interacting with and will merge in future.

One can look at the picture(s) for hours and appreciate the beauty, the colours, spiral arms, ‘dust lanes’; it is hypnotic and after a while creates illusion of inward spiralling movement.

Now zoom into the image, you will see bright Red and Blue specks/dots/patches. Based on experience with the Andromeda post/picture, one would be tempted to appreciate these innumerable ‘apparent stars’, but no, Universe always has some surprise in its bag, and in this case, would you believe if I tell you that each of those specs is NOT a star, but it is a ‘Cluster of few LAKH stars’, yes you read that correctly.

Take a gasp and look at the picture again. I am sure you are looking at M51 much differently now :)

Links

1. Image Tour http://hubblesite.org/video/881/image_tours

Photos:

• M51 and M51b - Optical spectrum picture by Hubble Space Telescope

• M51 - Optical image with overlay of Hydrogen gas distribution (in blue)

• M51 in Infrared on the right, visible spectrum on Left.

The Infrared light passes through dust, visible light gets blocked. The dark spirals in the Left image are called dust lanes, those show up bright in the infrared as that dust is getting heated by the background light/radiation and emits (heat ) in infrared spectrum.

• M51 - composite with X-Ray radiation

• M51 and M51b sketch from 1850

  

M31 - Andromeda Galaxy

M31 - Andromeda Galaxy (Read the complete post and then visit the first comment)

गॅलक्सी कशी असते ते कितीतरी सुंदर फोटोतून आपण पाहिलेच असेल, पण ती काय असते हे बघायचे असेल तर अँड्रोमेडाचा आतापर्यंत काढलेला सर्वात डिटेल फोटो बघाच (लिंक पहिल्या कंमेंट मध्ये).

झूम करून शेवट पर्यंत पहा, शक्यतो मोठ्या/ कॉम्पुटर स्क्रीनवर. प्रत्येक ठिपका एक तारा आहे, जवळ-जवळ प्रत्येकाला कमी जास्त ग्रह असतील, अगणित ग्रहांवर जीवसृष्टी असेल आणि आपण त्याच्याशी बोलू शकणार नाही, कदाचित कधीच!

Here is another breathtaking picture of the Andromeda galaxy, highest ever resolution till date. This picture uploaded with the post is just a low resolution version. The actual image is jaw dropping, you really appreciate what a galaxy is. Make sure to use the Zoom Tool image viewer (Link in first comment) .

The blinding bright left corner is the galactic center. Go far right and those are the outskirts, zoom there too. Just click to zoom in, go to max possible magnification - each dot you see is a star.

So many stars, most of them would have their own planetary system and many uncountable ones with life with which we may never establish contact ever!

Comments/Links:

http://www.spacetelescope.org/images/heic1502a/zoomable