Behold a galaxy twice the size of the Milky Way!

Our Milky Way is just a spiral galaxy, but NGC 1232 here is a grand spiral galaxy, its diameter twice as long as ours. Everything is bigger in NGC 1232, including the giant satellite galaxy warping it out of shape.

Technically speaking, NGC 1232 is a grand design spiral galaxy, so named of its extremely well-defined spiral arms. But even then, its arms are unusual, as most spiral galaxies like this would have gently curved arms. NGC 1232 has much more sharply bent arms. That's likely because of the gravitational distortion of its satellite galaxy, the rather unimaginatively named NGC 1232A. While most large galaxies have satellite galaxies - there's a tiny one orbiting our galaxy just 70,000 light-years away - very few satellites are both so close and so massive.


This particular image was taken by the European Southern Observatory's Very Large Telescope back on September 21, 1998. The ESO explains how the image was created:

It is based on three exposures in ultra-violet, blue and red light, respectively. The colours of the different regions are well visible : the central areas contain older stars of reddish colour, while the spiral arms are populated by young, blue stars and many star-forming regions. Note the distorted companion galaxy on the left side, shaped like the greek letter "theta".

NGC 1232 is located 20º south of the celestial equator, in the constellation Eridanus (The River). The distance is about 100 million light-years, but the excellent optical quality of the VLT and FORS allows us to see an incredible wealth of details. At the indicated distance, the edge of the field shown corresponds to about 200,000 light-years, or about twice the size of the Milky Way galaxy.


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