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13Dec 2012

Hubble News: Deepest Images Pull Back Curtain on the Early Universe

Faye Flam
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Hubble's deepest image yet

Science writers took different approaches to Wednesday’s announcement that the Hubble had imaged galaxies further away than ever before and therefore shining at us from further back in time. One of those galaxies had been announced previously but with a slightly different estimate for its age.

The new findings were newsworthy since they pushed our view back toward the period when the first stars and galaxies were taking shape. The oldest of these galaxies is shining at us from just 380 million years into the 13.7 billion year history of the universe.

The latest pictures come out of a series of observations called deep field and now ultra-deep field. Astronomers point Hubble at a spot in the sky and collect light over a period of hours. The first deep field pictures released in the 1990s were instant icons, covering the front pages of newspapers around the world. Staring at a patch of seemingly empty sky turned out to be a very good idea.

This AP story by Alicia Chang led off with the slight update on the previously-discovered galaxy.

A galaxy once considered the oldest has reclaimed its title, scientists reported Wednesday.

Poring through Hubble Space Telescope photos, the team recalculated the galaxy's age and determined it is actually 13.3 billion years old — not a mere 13.2 billion.

This lede needed to put the numbers in perspective by reminding readers of the age of the universe. The age of the galaxy isn't going to mean much unless it's clear how close this is to the big bang.

This Reuters Story offered a more helpful perspective:   

Astronomers using the Hubble Space Telescope have found seven galaxies that formed relatively shortly after the universe's birth some 13.7 billion years ago, scientists said on Wednesday, describing them "as baby pictures of the universe."

One of the objects may be the oldest galaxy yet found, dating back to a time when the universe was just 380 million years old, a fraction of its current age.

I was surprised to see USA Today’s Dan Vergano define the term galaxy in the second paragraph of this story.

Hubble space telescope astronomers reported on Wednesday that the earliest galaxies formed slowly more than 13 billion years ago after the beginning of the universe.

Galaxies are the islands of stars filling the universe such as our own Milky Way. In the first census of the oldest galaxies, the Hubble team reported on seven seen in a Hubble "Ultra Deep Field" image, including the likely oldest one yet spotted, dating to 380 million years after the Big Bang.

I have no doubt that he’s correct in assuming many readers don’t know what a galaxy is. Still, I thought the definition could have been woven in more gracefully. And readers who don’t know what a galaxy is are unlikely to have a good mental image of the Milky Way, so his definition isn’t going to be helpful to the severely astronomically challenged. (If you’ve ever been out on a clear night with such people and tried to explain that we’re in the Milky Way, you know what I’m saying.)

And his use of the number 380 million will mean nothing to people who don’t know what a galaxy is. It may not mean much to more sophisticated readers. The number 380 million is impressive in this context because it’s small compared to the age of the universe. When it’s presented naked it’s confusing.

I liked blogger Phil Plait’s version of the story for Slate. His is fortunate enough not to have been forced to explain what a galaxy is.  He was clearly excited by the discovery and that was transmitted to the readers. He also brought in some interesting background on current thinking about the first generation of stars:

The reason this observation is important is that we know very little about what galaxies were like so far back in time. Galaxies like our Milky Way are big, sedate, and fully-formed, but that wasn’t always the case. When the Universe was only a few hundred million years old, there were no galaxies; they were just starting to form. The first stars forming from vast clouds of gas would, we think, be extremely massive—well over 100 times more massive than the Sun—and very hot. They would’ve flooded the Universe with ultraviolet light, making the surrounding gas glow at a very specific color in the UV. These baby pictures of the seven galaxies tell us what those conditions were like back then, including potentially how many of these ginormous stars existed at the time.

The BBC’s Jonathan Amos also captured the excitement in this excellent story while keeping it real and clear. 

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