Galaxies

• Galaxies


  Consist of stars, planetary systems, stellar dust and gas
• Voyager 1 and Voyager 2 space probes


  1. Launched from Earth in 1977

  2. Passed Jupiter in 1979

  3. Passed through the Kuiper belt

  4. Travelled beyond the edge of the Solar System

  5. Voyager 1 has travelled further than anything else made by humans
• Voyagers will spend over 10000 years travelling through the Oort cloud of objects weakly held by the gravity of the distant Sun
• When Voyagers exit the Oort cloud, they will still be inside the Milky Way galaxy
• Milky Way galaxy


  • One of thousands of millions of galaxies in the Universe
  • Hazy white band through the centre of the sky
• Milky Way


  Our galaxy, named after the Greek word for 'milky'
• Proxima Centauri is the nearest star to our Sun, with a diameter seven times smaller than our Sun's diameter
• There is at least one exoplanet orbiting Proxima Centauri, making it our nearest solar system
• Our Solar System and the Proxima Centauri solar system are part of the Milky Way galaxy
• Most of the stars that you can see are stars in the Milky Way
• Astronomers think our Sun and the other stars in our galaxy are all orbiting a huge black hole at the centre
• Milky Way


  A spiral galaxy, shaped with curved arms making a disc with a bulge in the middle
• The images we have of the Milky Way disc are models, not photographs that anyone could take from inside it using a camera
• The hazy white band in the sky is the concentration of stars that we see when we look along the disc
• When we look in other directions, there aren't as many stars
• Other galaxies


  Some of the bright, fuzzy objects in the night sky are other galaxies beyond the Milky Way
• Andromeda galaxy


  The nearest spiral galaxy to our own
• You can also see two of our other neighbouring galaxies, the Large and Small Magellanic Clouds
• Not all galaxies are spiral, and you need a telescope to see them in any detail
• Universe


  Everything that exists, including all the stars, planets, moons, comets, asteroids, meteors, and you
• We don't know how large the Universe is or whether it is even infinite, but we do know that we can see for 13.7 billion light years in all directions
• Earth

  A planet in a solar system located on a spiral arm of the Milky Way galaxy
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  The Sombrero galaxy is one of thousands of millions of galaxies in the universe
• The Triangulum Galaxy is a spiral galaxy 2.7 millions light years from earth