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SALT LAKE CITY — Over 400 million years ago, a large spiral galaxy collided with another, smaller galaxy in a violent event that led to the formation of a rare, ringed ubër-galaxy captured recently by the powerful new James Webb space telescope.
Images of the Cartwheel Galaxy, named for its spoke-and-ring structure that's reminiscent of a wagon wheel, have been previously captured, including in observations made by the James Webb Telescope's space-based predecessor, the Hubble. But the Webb telescope's advanced infrared imaging abilities allow it to "see" through the dust and space debris that have previously clouded details of the Cartwheel body, which is some 500 million light years from Earth and contains billions of stars.
Why does it look like a wheel? According to an explanation posted by the California Institute of Technology's Jet Propulsion Laboratory, the shape of the Cartwheel Galaxy is the direct result of the galactic collision that formed it. The black hole at the center of the body is surrounded by two rings — a bright inner ring and a surrounding, colorful outer ring. Jet Propulsion Laboratory scientists say those two rings have been expanding outward since the collision occurred, like "ripples in a pond after a stone is tossed into it." Those distinctive features are what characterize a "ring galaxy," a structure less common than spiral galaxies like our Milky Way.
While the initial collision led to the unique structure of the Cartwheel, much of the character of the large, spiral galaxy that existed before the epic space "accident" can still be seen, including the spiral's rotating arms. That leads to the "spokes" that inspired the name of the Cartwheel Galaxy, which are the bright red streaks seen between the inner and outer rings, according to a posting by Webb telescope scientists. And those brilliant red tones are the result of light reflected by hydrocarbon-rich dust.
Infrared Riding Hood: While the Hubble "sees" objects in the optical and ultraviolet spectrums, with some limited infrared capabilities, the Webb telescope is optimized for looking at the universe via the infrared spectrum. The Webb telescope also has a much larger mirror than the Hubble which collects more light and is able to peer farther back in time than the Hubble is capable of doing.
Fun facts: The Webb telescope launched into space last Christmas atop a European Ariane 5 rocket and traveled to a position 1 million miles from home, where it is orbiting the sun. While the first Webb images were transmitted back to earth in July, where the data is picked up by ground-based antennas in Australia, California and Spain, the Hubble is still in operation and making observations from its position about 340 miles above earth. Hubble launched in 1990 with an expected lifespan of about 15 years, but NASA scientists say it could continue operating until the late 2020s.