Light travels fast, but it isn’t instant. When you look at the Moon, you’re seeing it as it was 1.3 seconds ago. The Sun: 8 minutes ago. Other stars in our galaxy: years to thousands of years ago. Other galaxies: millions of years ago. The farthest objects we can see are also the oldest, because their light has been traveling toward us for almost the whole age of the universe.
The James Webb Space Telescope has now spotted galaxies whose light has been traveling for around 13.5 billion years. That means we’re seeing those galaxies as they were just 300 million years after the Big Bang, when the entire universe was less than 3% of its current age.
The strange thing is that these very early galaxies look more developed than astronomers expected. They had thought the first galaxies should be small and messy and slowly forming. JWST’s images show galaxies that already have clear shapes, well-organized stars, and chemical elements that take time to form. Astronomers are now rewriting parts of the universe’s early history to make sense of what they’re seeing.
