Ringing a Bulls-Eye

NASA/ESA Hub­ble

A galac­tic bulls-eye ringed with pink neb­u­lae is the only evi­dence of a rare galac­tic col­li­sion of NGC 922 that occurred mil­lions of years ago.

Explore this awe­some image from the NASA/ESA Hub­ble Space Tele­scope. What shapes or sto­ries do you see? Leave a note in the com­ments below.

NGC 922 used to be a spi­ral galaxy. But as you zoom across the image, the spi­ral arms look dis­torted and dis­rupted. Tell-tale signs of a galac­tic inter­ac­tion are many from the large num­bers of bright pink neb­u­lae and blue stars to the spray of dim stars toward the top of the image. Rip­ples set up as the smaller galaxy passed through the gas and dust clouds of NGC 922 cre­ated new star for­ma­tion. Ultra­vi­o­let radi­a­tion from these bright new stars cause hydro­gen gas in the sur­round­ing neb­ula to glow a char­ac­ter­is­tic pink. The tugs of grav­ity hurled thou­sands of stars outward.

Sci­en­tists believe that mil­lions of years ago a small galaxy, known as 2MASXI J0224301-244443, plunged through the heart of NGC 922. Some­times, if a small galaxy hits a larger galaxy just right, a cir­cle is formed. But more often than not, galax­ies are not aligned per­fectly. When a galaxy smacks another off cen­ter, one side of the ring is brighter than the other. NGC 922 is a prime exam­ple of what astronomers call col­li­sional ring galaxies.

As you explore the empty places of the image, look for far­away back­ground galax­ies. Sev­eral dim spi­ral galax­ies dot the image both out­side the galaxy and within the star-speckled interior.

NGC 922 is found about 330 mil­lion light-years from Earth toward the con­stel­la­tion For­nax. For­nax, the Fur­nace, is a con­stel­la­tion we haven’t vis­ited before. Intro­duced by sky map­per and French astronomer Nico­las Louis de Lacaille in 1756, For­nax is rel­a­tively devoid of stars allow­ing astronomers to peer deep into the uni­verse. Astronomers tar­geted For­nax for the Hub­ble Ultra Deep Field image.

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