Skip to comments.Astronomy Picture of the Day -- Unraveling NGC 3169
Posted on 03/28/2013 8:09:35 PM PDT by SunkenCiv
Explanation: Bright spiral galaxy NGC 3169 appears to be unraveling in this cosmic scene, played out some 70 million light-years away just below bright star Regulus toward the faint constellation Sextans. Its beautiful spiral arms are distorted into sweeping tidal tails as NGC 3169 (left) and neighboring NGC 3166 interact gravitationally, a common fate even for bright galaxies in the local universe. In fact, drawn out stellar arcs and plumes, indications of gravitational interactions, seem rampant in the deep and colorful galaxy group photo. The picture spans 20 arc minutes, or about 400,000 light-years at the group's estimated distance, and includes smaller, dimmer NGC 3165 at the right. NGC 3169 is also known to shine across the spectrum from radio to X-rays, harboring an active galactic nucleus that is likely the site of a supermassive black hole.
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The biggie version:
Sorry .................................................................................... FRegards
NGC stands for (you’re) Not Gust Cidding! ;’)
Thanks for all the beautiful pics.
I have a book entitled ASTRONOMY, copyrighted 1898 as part of The Concise Knowledge Library. It's written at about the level of an introductory college astronomy text. This was at a time when the knowledge of nebulae, including for example the Andromenda Nebulae, was very sparse, and the idea that the spiral nebulae might be "Island Universes" was considered wild-eyed speculation by a conservative establishment.
ASTRONOMY has a penultimate chapter on CLUSTERS AND NEBULAE, but leaves them behind when moving to the last chapter, THE STRUCTURE OF THE HEAVENS, which is devoted to the Milky Way. The author adduces various reasons to believe that Andromeda couldn't be more than 5 lys across, and considers this outrageously huge. Interestingly the appearance in Andromeda of a "temporary star" in 1885 is given as presumptive evidence that it could be no more than 200 parsecs ( 650 lys ) away, and thus "... not an external galaxy."
The consensus was that the Milky Way was the universe. The view that prevails today was considered looney and way out there. Naturally Harlow Shapley took the side of the consensus; while his estimate of the size of the Milky Way was more nearly correct, basically, he was dead wrong. Curtis was incorrect on his estimate of the size of the Milky Way, but had to underestimate distances to (for example) Andromeda galaxy because of the reactionaries like Shapley — and was correct, the Milky Way is just one galaxy out of (at least) millions.
NASA sez, “oh, kumbaya, they were both right!”
The Shapley — Curtis Debate in 1920
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