Reminder: I’ll in Cincinnati and Indiana all next week giving public talks about the April 8 total solar eclipse! If you’re in the area, come see. The times and locations are all listed in BAN Issue 684!

Also, I’m being interviewed for SETI Live tonight (Thursday) at 5:30 p.m about my book Under Alien Skies. You can watch it on YouTube.

One of the fun things about being familiar with astronomical objects is being able to look at one and go, “Yup, I know what just happened there.” This is never more obvious than when a galaxy has undergone a collision with another galaxy. There are a lot of things that can happened during a collision and merger, including the two galaxies pulling out long tidal tails, increased star formation, high-energy activity from the central supermassive black hole, and more.

It also depends on how big the two galaxies were relative to one another. If a big one eats a smaller one you don’t always get all the overblown drama of two heavyweights battling it out, but it still produces dramatic scenes all the same.

Take a gander at NGC 4753:

This image was taken using the Gemini South telescope in Chile, using three filters that kinda mimic the way our eyes see, but only kinda. What you see as blue here is a wavelength of 475 nanometers, which really is blue. But what’s displayed as green is actually 630 nanometers, which is orange-red. What’s shown as red is near-infrared at 780 nm. So it’s close to what our eyes see.

NGC 4753 is technically a lenticular, a lens-shaped galaxy that has some aspects of being a spiral (like having a disk shape) but also some of an elliptical (a lack of gas and dust, usually). But as you can see, there’s dust! Those absolutely gorgeous gossamer filaments are made of countless clouds of tiny grains of silicaceous (rocky) and carbonaceous (sooty) grains of dust, so small you’d need a microscope to spot them individually, but so abundant that the clouds can be several light-years wide, and the streamers tens of thousands of light-years long.

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