The scale of the universe

This bundle of bright stars and dark dust is a dwarf spiral galaxy known as NGC 4605, located around 16 million light-years away in the constellation of Ursa Major (The Great Bear). This galaxy’s spiral structure is not obvious from this image, but NGC 4605 is classified as an NGC 4605 is a member of the Messier 81 group of galaxies, a gathering of bright galaxies including its namesake Messier 81 ( The Messier 81 group is one of the nearest groups to our own, the Local Group, which houses the Milky Way and some of its well-known neighbours, including the Andromeda Galaxy and the Magellanic Clouds. Galaxy groups provide environments where galaxies can evolve through interactions like collisions and mergers. These galaxy groups are then lumped together into even larger gatherings of galaxies known as clusters and superclusters. The Local and Messier 81 groups both belong to the With so many galaxies swarming around, NGC 4605 may seem unremarkable. However, astronomers are using this galaxy to test our knowledge of stellar evolution. The newly-formed stars in NGC 4605 are being used to investigate how interactions between galaxies affect the formation, evolution, and behaviour of the stars within, how bright stellar nurseries come together to form stellar clusters and stellar associations, and how these stars evolve over time. And that's not all — NGC 4605 is also proving to be a good testing ground for Credit:

Everywhere we point telescopes in the sky, we see On even grander scales, what became galaxies and clusters began as froth on huge cosmic sound waves during the era when the universe was a hot cauldron of particles and light. These waves are called “baryon acoustic oscillations”, and they provide us with a way to measure the expansion rate of the universe, including the mysterious acceleration caused by dark Center for Astrophysics | Harvard & Smithsonian scientists lead many studies of the large-scale structure of the universe and baryon acoustic oscillations. Two examples include: • Using surveys of thousands of galaxies across the sky to create a three-dimensional map of the cosmic web and galaxy-free voids. CfA astronomers led the first measurement of large-scale structure with the CfA Redshift Survey inaugurated in 1977. Modern projects include the 2MASS map of galaxies in infrared light, the Sloan Digital Sky Survey (SDSS), and the Pan-STARRS survey. • Surveying galaxies and quasars to map baryon acoustic oscillations, the ripples in the sky larger even than the cosmic web. The Baryon Oscillation Spectroscopic Survey (BOSS) is an ongoing project to map tens of thousands of galaxies, to improve our techniques of measuring cosmic distances, as well as to understand dark energy. The Large-Scale Structure of the Universe A completely homogeneous universe would have no stars, galaxies, or planets. As it turns out, when it began, our universe was almost completely homogene...