If you’re at all a fan of astronomy, you’ve probably marveled over the many beautiful photos of spiral galaxies that are out there. Like this one of NGC 3344 captured by the Hubble Space Telescope.
Credit: ESA/Hubble & NASA
But you may not know that galaxies have not always looked this way. The grand spirals we are so familiar with were formed over the course of billions of years by the collisions of smaller galaxies. Though, when spirals collide with a similar-sized galaxy, the disruption can cause them to merge and evolve into a giant elliptical galaxy. According to an article in Nature News, based on a survey of galaxy shape and structure (current to 2009), it is thought that “nearly all massive galaxies have undergone at least one major merger since the Universe was 6 billion years old.”
Giant elliptical galaxy, M87, located in the Virgo cluster
When we look at very distant galaxies, we see a completely different picture. Older galaxies tend to be small and clumpy, often with a lot of star formation occurring in the massive clumps. The question of how these clumpy galaxies evolve and develop structure over time is a big open question in astronomy, and we hope that the powerful up-and-coming James Webb Space Telescope will help astronomers to learn more.
Clumpy galaxy spied by the Hubble
Clumpy galaxies spied by the Hubble