Astronomers spot a strange, supersonic space cloud screeching through our galaxy

While focussing on the remains of an exploded star roughly 10,000 light-years away, a team of Japanese astronomers have stumbled across a mysterious cloud of molecules tearing through the Milky Way. So quickly, in fact, they’ve nick-named it the unknown phenomenon the ‘Bullet’.

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a cloud of molecules 2 light-years in size was moving forward at 120 kilometres per second, and expanding at 50 kilometres per second. Weirder still, it was moving against the direction of the Milky Way’s spin.

I wonder how that compares with fast stars and jets.

The nearby fast star Kapteyn’s star has a Doppler shift velocity of 245 km/s. There are many stars much faster than this. So the speed of the molecular cloud isn’t really very fast.