Milky way galaxy

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The center of our Milky Way galaxy is hidden from the prying eyes of optical telescopes by clouds of ... [+] obscuring dust and gas. But in this stunning vista, the Spitzer Space Telescope's infrared cameras penetrate much of the dust, revealing the stars of the crowded galactic center region. The upcoming James Webb Space Telescope will offer a much-improved infrared view, teasing out fainter stars and sharper details. NASA, JPL-Caltech, Susan Stolovy (SSC/Caltech) et al. Our Sun’s journey around the Milky Way’s galactic center puts it through some of the most complicated motions imaginable. Since time immemorial, astronomers and celestial mechanics have struggled to understand the how and why of our Star’s journey through the galactic disk. The Sun makes one orbit around the Milky Way roughly once every 225 million years and is thought to have made this journey some 20 times since its earliest days as a protostar. We now know the orbital speed of the Sun in its Galactic orbit to better than two percent accuracy (or roughly 247 kilometers per second), Mark reid, an astronomer at the Harvard Smithsonian Center for Astrophysics, told me.The Sun is in a nearly circular orbit, with a slight ellipticity (of about five percent), he says. On the largest scales, from great distances, the Milky Way would appear as a classic grand spiral galaxy, with four spiral arms.And our spot in the much ballyhooed suburbs of the galaxy’s disk isn’t a bad place to be.It’s far enough away from t...

Even though the spiral arms of a galaxy look stunning and impressive, they are not much denser with stars than the gaps between them. A typical spiral arm has only about 10% more stars than average, so spiral arms aren't regions of greater stellar concentration. Instead, the arms represent places of greater-than-average star formation. The arms are density waves, their formation triggered by gravitational interactions with satellite galaxies, that travel through a galaxy at their own speed, like ripples in a pond. As the waves travel, they slightly increase the density in that region of space as they pass by. When that happens, clouds of gas destabilize and collapse, leading to a new round of star formation. Related: The Milky Way galaxy may be a different shape than we thought Those clouds go on to form all sorts of stars, from small red dwarfs to blue giants. Those giant stars don't last long; a typical star of that size lasts only a few million years. By the time the spiral density wave finishes passing through, all of those stars will be gone, leaving behind only their smaller, dimmer siblings. Young clues It's relatively easy for astronomers to map the spiral structures of many distant galaxies, especially if they appear to us face-on. But creating a detailed map of our own Milky Way's arms is much more difficult. Because we are embedded within the same galactic disk as the arms, we have to contend with tens of thousands of light-years of gas and dust, which are very ...

"It's the dawn of a new era of black hole physics," the Event Horizon Telescope team said as it released the first-ever image of supermassive black hole in the center of the Milky Way. EHT Collaboration For years, the supermassive black hole in the dark center of the Milky Way galaxy has been theorized about and studied — and finally, it's been captured in an image. "We finally have the first look at our Milky Way black hole, Sagittarius A*," an international team of astrophysicists and researchers from the Event Horizon Telescope team "It's the dawn of a new era of black hole physics," it added. The black hole is often referred to as Sgr A*, pronounced sadge ay star. Its mass is about 4 million times that of the sun, and it's about 27,000 light years from Earth, Black holes have long been a source of public fascination, but they also pose notorious challenges to researchers, mainly because their gravitational fields are so strong that they either bend light or prevent it from escaping entirely. But scientists have been able to detect and study them based on the powerful effects they exert on their surroundings. In the case of Sgr A*, scientists have YouTube Putting the size of the black hole into an Earthling's perspective, the team said that seeing it from the surface of our planet would be like trying to spot a donut on the moon. "What made it extra challenging was the dynamic environment of Sgr A*, a source that burbled then gurgled as we looked at it," Özel said, "and...

The Milky Way is our galactic home, part of the story of how we came to be. Astronomers have learned that it’s a large spiral galaxy, similar to many others, but also different in ways that reflect its unique history. Living inside the Milky Way gives us a close-up view of its structure and contents, which we can’t do for other galaxies. At the same time, this perspective makes it difficult for astronomers to obtain a complete picture of galactic structure. Modern research on the Milky Way refines our understanding of how the Center for Astrophysics | Harvard & Smithsonian astronomers use many methods to study the Milky Way: • Measuring precise distances and 3-dimensional motions for massive star-forming regions in the disk of the Milky Way in order to map out its spiral structure and determine its overall size and rotation speed. CfA astronomer Mark Reid is leading an international team of astronomers on the • Looking for the remnants of the galaxies the Milky Way is built from. We know our galaxy grew by merging from smaller galaxies, because traces of that history are visible. That process continues today as the Milky Way strips stars from its satellite galaxies, producing “tidal streams” and other measurable effects. • Tracing the history of Sgr A* and the way it affects the rest of the galaxy. While our supermassive black hole is quiet today, astronomers have found signs it hasn’t always been that way. Studying the cycles of activity in Sgr A* helps us understand the ...

The new paper, which has not yet been peer-reviewed, poses a peculiar question: What are the odds that humans could one day contact a hostile alien civilization that's capable of invading our planet? To answer this, sole study author Alberto Caballero — a doctoral student in conflict resolution at the University of Vigo in Spain — began by looking back at human history before looking out to the stars. "This paper attempts to provide an estimation of the prevalence of hostile extraterrestrial civilizations through an extrapolation of the probability that we, as the human civilization, would attack or invade an inhabited exoplanet," Caballero wrote in the study. Related: 9 things we learned about aliens in 2021 (Caballero is not an astrophysicist, but he has published a study on the infamous Wow! signal— a potential sign of extraterrestrial life — in the peer-reviewed International Journal of Astrobiology.) To reach his estimation, Caballero first counted the number of countries that invaded other countries between 1915 and 2022. He found that a total of 51 of the world's 195 nations had launched some sort of invasion during that period. (The U.S. sat at the top of the list, with 14 invasions tallied in that time.) Then, he weighted each country's probability of launching an invasion based on that country's percentage of the global military expenditure. (Again, the U.S. came top with 38% of global military spending.) From there, Caballero added each country's individual prob...