Fascinating Galaxy Astronomy extras that wouldn’t fit into the book. First up are the Antennae Galaxies
Antennae Galaxies
NGC 4038 & NGC 4039 form the Antennae galaxies. What looks like one strange galaxy is really two galaxies that have been moving close to each other for millions of years. The image in Galaxy Astronomy was a close-up view of the two spiral galaxies. But the name—Antennae—came from the long curving streaks of stars that you can see here.
As these two galaxies approached, gravity pulled at stars in each one. People looking through telescopes on Earth saw those curving streaks and thought of long antennas on an insect. While the catalog numbers NGC 4038 and NGC 4039 are the official names, most people like Antennae galaxies better. The word antennae is from the old Roman language, Latin. In ordinary English, we say antennas.
For comparison, here’s the close-up image from the Galaxy Astronomy book.
All images are licensed under Creative Commons, Attribution 4.0 International license.
Galaxy Astronomy Sources
Want to dig deeper into astronomy? One place to begin is where I got the images for Galaxy Astronomy. Most of them came from the Hubble Space Telescope and the European Space Agency (ESA). Visit the ESA Hubble website and type in the name of a galaxy you want to explore.
Four galaxy entries showed double images, one in visible light and the other in UV light. The UV images came from the GALEX orbiting space telescope. The GALEX mission was a joint effort of the California Institute of Technology and NASA’s Jet Propulsion Laboratory. Learn more about GALEX here and search for galaxies observed in UV light.
The wide-angle view of the Antennae galaxies came from Wikipedia’s Antennae Galaxies page. To see the image I used and read the details about the file, click on the link above, then on the Hubble image displayed on the Wikipedia page. You can then scroll to the wide-angle view.
Spiral Galaxies
Galaxy Astronomy is a great starter book. Astronomers know much more about spiral galaxies, and you can explore that knowledge online. Before I wrote the book, I spent hours learning all I could about each type of galaxy. Wikipedia is not the only site to explore, but it is a good one to visit.
Wikipedia has a long page called Galaxy Evolution. It talks about what early astronomers thought the fuzzy blobs were and how we realized they were actually galaxies. Another page named Spiral Galaxy dives deep into spiral galaxies. You can read about astronomer Edwin Hubble’s galaxy classification method. There’s a fun video simulation of how spiral arms form as stars orbit the core, moving into and out of spiral arms over time. In the video, stars orbit the core and the spiral arms rotate at a slower pace. Just remember, it takes the Sun over 200 million years to orbit the Milky Way core once. And if you want to know more about our home galaxy, visit the Milky Way page.
Other Galaxies
Here’s a wonderful video zoom that ends at the giant elliptical NGC 1316.