Observations made with the Hubble Space Telescope show how our galaxy has grown over billions of years. Thanks to evidence gathered by the Hubble Space Telescope , NASA has been able to determine what our galaxy looked like billions of years ago. Though the space agency obviously wasn't able to take actual photographs of the Milky Way in its infancy, it intuited its conclusions based on Hubble's observations of similar galaxies. The Hubble images suggest that our galaxy's flat disk and central bulge grew simultaneously into the majestic spiral galaxy of today The survey reveals that billions of years ago, the Milky Way was likely a faint, blue, low-mass object containing lots of gas, the fuel for star birth.
First globular cluster outside the Milky Way | ESA/Hubble
Most of these stars are red giants. The first direct measurement of the bar-shaped collection of stars at the centre of our Milky Way galaxy has been made by combining data from the Gaia mission European Space Agency, ESA with complementary observations by ground- and space-based telescopes. The second release of data from Gaia star-mapping satellite, published in , has been revolutionising many fields of astronomy. The unprecedented catalogue contains the brightness, positions, distance indicators and motions across the sky for more than one billion stars in our Milky Way galaxy, along with information about other celestial bodies. This is just the beginning. New data releases planned in coming years will steadily improve measurements as well as provide extra information that will enable us to chart our home galaxy and delve into its history like never before. The team combined the second Gaia data release with several infrared surveys using a computer code called StarHorse, developed by co-author Anna Queiroz and other collaborators.
Gaia Makes First Direct Measurement of the Galactic Bar in the Milky Way
The universe 13, million years ago was very different from the universe we know today. It is understood that stars were forming at a very rapid rate, forming the first dwarf galaxies, whose mergers gave rise to the more massive present-day galaxies, including our own. However the exact chain of the events which produced the Milky Way was not known until now. Exact measurements of position, brightness and distance for around a million stars of our galaxy within 6, light years of the sun, obtained with the Gaia space telescope, have allowed a team from the IAC to reveal some of its early stages.
The object shown in this beautiful Hubble image, dubbed Messier 54, could be just another globular cluster, but this dense and faint group of stars was in fact the first globular cluster found that is outside our galaxy. Current estimates indicate that the Sagittarius dwarf, and hence the cluster, is situated almost 90 light-years away — more than three times as far from the centre of our galaxy than the Solar System. Ironically, even though this globular cluster is now understood to lie outside the Milky Way, it will actually become part of it in the future.