Watch: The Milky Way as You’ve Never Seen It Before

In April 2018, the European Space Agency’s Gaia observatory released its second data catalog, which includes the distances to over 1.3 billion stars. In the video published by the American Museum of Natural History, museum’s astrophysicist Jackie Faherty breaks down why this information is so revolutionary and explains how this information is helping scientists and non-scientists alike understand the universe like never before.

Fly through the galaxy with Museum astrophysicist Jackie Faherty, who takes us on a dazzling tour of new research and data visualizations made possible by recently released data from the Gaia space telescope. This SciCafe took place on October 3, 2018.

Some key points from the video

  • In the beautiful photo below, you cannot tell how far away the objects are. You cannot tell those two galaxies are “galaxies”. You cannot tell which one is the closest star to us. You need something else to say that kind of things – and it’s “science”. Science will give you the answers to things, like, “how far away is a star?”
Milky Way from Las Campanas Observatory. Photo by Yuri Beletsky
This is a picture of the nighttime sky – the best kind of nighttime sky that anybody on Earth could hope to see. It was taken from the Las Campanas Observatory in northern Chile by astronomer Yuri Beletsky. In this photo, you’re seeing a fairly realistic image of what the nighttime sky should really look without light pollution. Notice there’s a red dot at upper right corner: it is a total lunar eclipse. And at the left handside, you can see the large and small Magellanic clouds, which are two irregular dwarf galaxies, orbiting the Milky Way. In other words, they are the satellite galaxies of our galaxy. You can also see the Earth’s multi-colored airglow.
  • You can’t see also the “motion” in this image. All of these stars, everything in this beautiful photo, including the total lunar eclipse in Chile, is moving. We can learn a tremendous amount about our galaxy by looking at how far away the stars are and how they move.
  • On April 25, 2018, the entire perception of the Milky Way – the entire perception of the astronomy was changed. European Space Agency’s Gaia spacecraft came out on April 25 and released 1.7 billion parallaxes – distances to stars and motion.
  • Modern astrophysics was based upon 120,000. 1.7 billion is what we got on April 25.
Gaia spacecraft (artist conception)
Artist’s impression of the Gaia spacecraft. Image: ESA.int. Gaia is a space observatory of the European Space Agency (ESA) designed for astrometry: measuring the positions and distances of stars with unprecedented precision. The mission aims to construct the largest and most precise 3D space catalog ever made, totaling approximately 1 billion astronomical objects, mainly stars, but also planets, comets, asteroids and quasars among others.The spacecraft was launched on December 19, 2013, with a planned mission duration of five years and possible extension by one to four years. Gaia will monitor each of its target objects about 70 times over a period of five years to study the precise position and motion of each target. The spacecraft has enough consumables to operate for approximately nine years, and its detectors are not degrading as fast as initially expected. The mission could, therefore, be extended. The Gaia targets represent approximately 1% of the Milky Way population with all stars brighter than magnitude 20 in a broad photometric band that covers most of the visual range. Additionally, Gaia is expected to detect thousands to tens of thousands of Jupiter-sized exoplanets beyond the Solar System, at least 500,000 quasars and tens of thousands of new asteroids and comets within the Solar System.
  • Faherty visualizes a subset of Gaia data – which include a couple of hundreds of thousands of the hottest stars in the Milky Way galaxy and says: “We didn’t take that picture. The Voyager 1 is the farthest thing we ever sent and it has barely left the solar system. So we’ve never taken a picture of the galaxy. But what we’re able to do in this map, is detecting the shape of the Milky Way galaxy.”
  • What do spiral arms of the Milky Way galaxy look like? Now you can use these stars as a map to try and get to that structure.  
  • If you know how stars are moving, and if you know how far away they are, you can look at their trajectories. We were stuck in this static view (the night view of Earth’s sky), what the galaxy looks like right now, what the nearby stars looks like right now. But once Gaia spacecraft showed up with all of these motions and distances, we can turn time on, and you can see the past and the future of the galaxy. Ar these have always been the closest stars to us? Did we ever have a flyby? Did another star come sweeping through our solar system and sending some comets and asteroids from the Kuiper belt Notes 1 and the Oort cloud Notes 3 towards the inner solar system? We can turn time on the Gaia data and find out.

Something wicked this way comes.

William Shakespeare. Macbeth, Act IV, Scene I.
  • Faherty then turns on the time and shows the future of the solar system. According to Gaia data, in 1.2 million years, a star called Gliese 710 Notes 4, which is about 60 percent of the mass of the Sun, is going to come within the Oort cloud. When it does that, it sends stuff into the inner solar system. (See: How Earth could die? 8 horrible ways)
Kuiper Belt and Oort Cloud
Kuiper Belt and Oort Cloud. Image: Wikimedia
  • Using the Gaia data, astronomers traced back where Oumuamua, a cigar-shaped asteroid became the first confirmed interstellar object observed traveling through our Solar System, might have come from. Before Gaia, we’ve never been able to trace back the motion of an object that came from a completely different solar system.
  • Another thing that we can do with this gigantic dataset, is looking for objects (i.e. stars) that move together. This is important to figure out where do stars come from? How do they evolve? How do they end up interacting with each other? Do they stay together? Are these small star groups are just the last bits of the core of a giant region of stars that had formed together millions or billions years ago? This is the kind of stuff the scientists trying to figure out now. Faherty says: “It’s like a forensic evidence that we didn’t have before and all of a sudden we have accessed to.”
  • Gaia also gave us an unprecedented look of young stars, where baby solar system born. You can run time backward and forward and see how they interact with each other.
  • Since 1995, Kepler Space Telescope is discovering exoplanets. Since 1995, it discovered thousands of them. Faherty shows how they all mapped properly with their distances from Gaia. She then turns time on and shows where these solar systems came and where they are going.

Faherty adds: “If you’re interested in playing with the data, this is not just for astronomers. This is for the public, this is for everybody. So, download our software, download the data, and play with it. It’s 1.7 billion stars, that’s too many for the astronomers. There are not enough astronomers for all of the data. So, please consider this to the invitation to the party of mapping the galaxy.”

Most Detailed Map of Milky Way Galaxy by Gaia Spacecraft. April 2018.
This is the most detailed and accurate map of Milky Way Galaxy, created by ESA (European Space Agency) scientists using the data acquired by Gaia Spacecraft. It was released on April 25, 2018. The map includes high-precision measurements of nearly 1.7 billion stars and revealing previously unseen details of our home Galaxy. Image: ESA (European Space Agency) Science & Technology website. You can also see the high-resolution image (8000×4000 pixels, 58.2 Mb) there. Gaia is a space observatory of the European Space Agency (ESA) designed for astrometry: measuring the positions and distances of stars with unprecedented precision. The mission aims to construct the largest and most precise 3D space catalog ever made, totaling approximately 1 billion astronomical objects, mainly stars, but also planets, comets, asteroids and quasars among others. The spacecraft was launched on December 19, 2013, with a planned mission duration of five years and possible extension by one to four years. Gaia will monitor each of its target objects about 70 times over a period of five years to study the precise position and motion of each target. The spacecraft has enough consumables to operate for approximately nine years, and its detectors are not degrading as fast as initially expected. The mission could therefore be extended. The Gaia targets represent approximately 1% of the Milky Way population with all stars brighter than magnitude 20 in a broad photometric band that covers most of the visual range. Additionally, Gaia is expected to detect thousands to tens of thousands of Jupiter-sized exoplanets beyond the Solar System, at least 500,000 quasars and tens of thousands of new asteroids and comets within the Solar System.

Notes

  1. The Kuiper belt is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger – 20 times as wide and 20 to 200 times as massive. Like the asteroid belt, it consists mainly of small bodies or remnants from when the Solar System formed.
  2. The astronomical unit (AU) is a unit of length, roughly the distance from Earth to the Sun. Since 2012 it has been defined as exactly 149,597,870,700 meters or about 150 million kilometres (93 million miles).
  3. The Oort cloud, sometimes called the Öpik-Oort cloud is a theoretical cloud of predominantly icy planetesimals believed to surround the Sun to as far as somewhere between 50,000 and 200,000 AU (0.8 and 3.2 light years). It is named after astronomer Jan Oort, who first theorized its existence. 1 AU (Astronomical Unit) is the distance between Earth and Sun, which is now defined as exactly 149,597,870,700 meters (about 150 million kilometers, or 93 million miles).
  4. Gliese 710 currently is 63.8 light-years (19.6 parsecs) from Earth. It is projected with a reasonable probability to have a close encounter with the Sun within the next 15 million years. The predicted minimum distance is 1.281 million years from now, possibly approaching as close as 0.0676 parsecs, 0.221 light years or about 13,300 AU, being about 20 times closer than the current distance of Proxima Centauri. It will then reach a similar brightness to the brightest planets, perhaps reaching an apparent visual magnitude of about -2.7 (brighter than Mars at opposition). The maximum total proper motion will peak around one arc minute per year, whose apparent motion will be able to be noticed over a human lifespan.

Sources

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