On October 24, a team of scientists announced the discovery of a faraway galaxy, called Z8-GND-5296 (Zate for friends). A very faraway galaxy, 30 billion light years away. It’s also quite old, 13.1 billion years old.
We’ve always wanted to know where we are
Our earliest maps were of the stars: Paleolithic depictions of constellations have been found in caves in France and Spain. Our ancient forebears had only the naked eye to find our place in the sky.
Today’s scientists are increasingly able to see further as the instruments that look into space improve. The “observable universe” extends about 46 billion light years away from Earth. Here’s an amazing 3-D map of our known universe.
The distance to Zate, 30 billion light years, is the furthest recorded so far for a galaxy.
How can Zate be 30 billion light years away if the universe is 13.8 billion years old and nothing travels faster than light?
The short answer is that the universe is expanding. Objects, especially distant ones, appear to be moving away from us. They aren’t. The space between us is increasing.
Having trouble wrapping your head around it? Yeah, me too.
Imagine that Galaxy Zate is on a moving walkway in the airport heading to the gate, while we’re on a walkway to the baggage claim. Zate sent us a paper airplane with a message, but since the distance between us keeps expanding, it took thirteen billion years to arrive.
The walkway is two-dimensional, while space is three-dimensional, and there’s no “center” out of which the universe expands, so the analogy is far from perfect, but it might help.
Did you say that was the short answer?
I did. It turns out that the limitation on objects moving faster than light refers to special relativity, that is to motion through space. There is no such limitation on the expansion of space itself. In case you didn’t click before, for a wonderful, and concise, explanation of the Big Bang and the expanding universe go here.
What can we learn from Zate?
The new galaxy appears particularly enriched in metals, which result from the formation of stars. Zate is thought to have produced 330 stars with a size equivalent to our sun every year. That’s a hundred times larger than the current rate for the Milky Way.
Zate and galaxies like it are very important to understand the early universe, when it was a mere 700 million years old, when stars and galaxies were being created.
How can you show creation?
Current scientific thought of the evolution of the universe looks something like the NASA schematic shown above.
Five hundred years ago in Europe, the understanding of creation was largely based on the Bible, but observations also mattered.
A particularly delightful representation of creation is the 1445 panel showing The Creation of the World and the Expulsion from Paradise by Giovanni di Paolo (1400-1482) in the Robert Lehman Collection of the Metropolitan Museum of Art in New York.
The Maker, surrounded by blue cherubim, is in the upper left, pointing to a cosmological representation of the universe as a series of concentric spheres. This is known as a thema mundi, a star chart of the world, where the outer ring holds the signs of the zodiac, that is, the constellations at the moment of earth’s creation.
Earth in the center
As asserted by Ptolemy and adapted to accommodate prevailing Christian thought of the time, the earth is central, fixed and unmoving. Copernicus didn’t publish mathematical foundations for heliocentrism until 1542, though the work had been written ten years earlier.
The innermost sphere, earth, is brown, and the next three spheres represent the remaining three elements (water, air, and fire in red). These are surrounded by the seven “planets:” the moon, Mercury, Venus, the sun (white, with remains of a gilded star), Mars (pink), Jupiter (light blue), and Saturn (darker blue). The “fixed stars” that were thought not to move, including the zodiacal constellations, surround Saturn. Finally, God with the angels is in the celestial orb, outside the concentric circles.
Both Medieval and Renaissance
Laurinda Dixon explains in a wonderful article that the artist broke with medieval tradition by showing the earth as a world map. Though superficially similar to the symbolic mappamundi of the Middle Ages, closely bound by Christian iconography, Giovanni di Paolo was clearly aware of the latest maps of his time. For example, the map’s top is the south instead of the medieval east and it’s not centered on Jerusalem.
However, Giovanni di Paolo’s map is still symbolic. Eden is located atop the Mountain of the Moon, near the headwaters of the Nile. As in medieval mappamundi, the four rivers of paradise flow from Eden, and can also be seen below Paradise in the Expulsion scene.
Where we are remains the same
This Earth. This beautiful planet. But how we define it varies.
Galaxy Zate can tell us about the first hundreds of millions of years of the universe’s existence. It can help confirm or disprove our understanding of things that are hard to imagine. Giovanni di Paolo’s Creation reflects the knowledge from a time straddling the arbitrary periods of Middle Ages and Renaissance.
We’ve always wondered where we come from and we always will. We’ll never have all the answers, but we’ll keep exploring and asking better questions, and then we’ll tell stories about what we learn.
And in this way, we’ll learn even more.