Stargazing: Newly discovered galaxy grows on its own time
Conventional astrophysical wisdom says that our universe began in an unimaginably powerful event 13.7 billion years ago, known as the Big Bang. Conventional astrophysical wisdom also states that the first stars formed a few million years after that and the first galaxies didn't appear until nearly a billion years after the Big Bang.
Apparently, a faint smudge of light, known as MACS 1149-JD, spied by both the Hubble telescope and the Spitzer Infrared telescope, doesn't follow conventional astrophysical wisdom. It formed a mere 500 million years after the Big Bang. “This galaxy is the most distant object we have ever observed with high confidence,” said Wei Zheng, a principal research scientist in the department of physics and astronomy at Johns Hopkins University in Baltimore, and who is lead author of a new paper on the new discovery appearing in Nature magazine.
The galaxy is so distant and so faint, even the powerful space-based telescopes couldn't directly see it. They were aided by a concept, first described by Albert Einstein nearly a century ago, called gravitational lensing. According to Einstein, light is bent and focused by gravity just as it would be by a glass lens. A giant cluster of galaxies between us and the newly-discovered distance champ focuses its light by the action of the cluster's gravity. This brightened MACS 1149-JD enough that the two telescopes could capture its light and create an image to determine its distance.
Irregular red blob
The images reveal a splotchy, red blob, rather irregular in shape. The deep red coloration of the galaxy is due to a phenomenon known as Doppler shift. It is moving away from us at high speed, due to the universe's expansion.
By measuring how fast it recedes, that is, by how reddened its light has become, we can calculate its distance from us. And in the 13.2 billion years its light has traveled to us, the galaxy has evolved and, now, it may well be a grand spiral galaxy, like our Milky Way is today.
Any intelligent inhabitants of MACS 1149-JD that have pointed their space telescopes our way would not yet see us, as our galaxy hadn't formed that long ago. It will be roughly another 500 million years, from their point of view, before our galaxy begins to shine, and another 9.1 billion years before our own sun forms.
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