This Distant Spiral Galaxy Looks Very Familiar

By Kiona Smith-Strickland on at

This is what observers in a distant galaxy would see if they could look at the Milky Way through a powerful space telescope.

It’s LEDA 89996, a spiral galaxy very similar to the Milky Way, and the Hubble Space Telescope captured this detailed image from its orbit around the Earth. From Earth, we can see LEDA 89996 face-on, which gives us a great view of the galaxy’s spiral structure. We can’t get a face-on view of the Milky Way because we’re inside it, on one of the spiral arms far from the centre. What we can see tracing a starry path across the night sky is actually only the edge of one arm of the galaxy; it’s sort of like the old adage about not being able to see the forest for the trees.

But because we’re so far away from LEDA 89996, and because it happens to be at just the right angle, we can see its whole spiral. Notice that the centre of the galaxy looks redder than the stars far out in the spiral arms, which look bright and blue. That’s because the stars in the spiral arms are younger than the stars near the centre of the galaxy; because space is expanding, things that are farther away look redder, because light wavelengths change as they move away. This is called Doppler shift.

The clouds of darker material are gas and dust drifting in the space between the stars. If you look up at the nearest arm of the Milky Way, you’ll see that our galaxy has very similar clouds.