Sometimes, a picture worth a thousand words can take five different wavelengths of light to create.
That’s the process behind this photo of the Crab Nebula, a cloud of dust and gas left over from a supernova about 6,500 light-years away, in the outer edges of the Milky Way. Astronomers used data from five telescopes, each built to observe the universe in different parts of the electromagnetic spectrum, to generate the detailed image. The result, released Wednesday, is an unprecedented view of the Crab Nebula in radio, infrared, visible, ultraviolet, and X-ray waves. It’s the ultimate cosmic composite photograph.
Let’s break it down by telescope and wavelength. The red in the photo comes from the Very Large Array radio telescope, located in the desert of New Mexico:
The yellow comes from NASA’s Spitzer Space Telescope, which recently helped another group of astronomers discover the seven Earth-sized exoplanets around TRAPPIST-1, a distant star system:
NASA’s Hubble Space Telescope, which has been photographing swirling galaxies in visible light since the 1990s, provided the green:
The European Space Agency’s XMM-Newton space telescope sees objects in ultraviolet light, which is blocked by Earth’s atmosphere. It provided the blue:
And the purple came from NASA’s Chandra X-Ray Observatory, which is designed to spot the X-ray glow from the hottest parts of the universe, like the aftermath of an exploding star:
The first observations of the Crab Nebula date back to 1054, when Chinese, Japanese, and Arab astronomers reported the sudden appearance of a bright star.* For several months, the mysterious glimmer appeared brighter than other stars and planets in the sky, a luminous pinprick of light coming from a stellar explosion shining as brightly as 400 million suns.
The light eventually faded from view about two years later, and from interest for hundreds of years, until telescopes came along to give astronomers a better look. Modern astronomers have used multiple images of the nebula taken over the years to study the rate of expansion of the cloud, and use it to trace the explosion date back to the initial reports from Asia.
Nearly a millennium after the explosion that created it, the Crab Nebula continues to expand. A dense neutron star called a pulsar spins at its center, rotating once every 33 milliseconds, producing powerful particle-swirling winds, and spewing electromagnetic radiation. If the supernova had occurred closer to Earth, the explosion would have wiped out all life on the planet. At this distance, though, it produces a pretty cool GIF.
* This article originally misstated the year of the earliest observations of the Crab Nebula. We regret the error.
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