Ghosts of Milky Way’s Powerful Past Revealed
In the image: This artist’s conception shows an edge-on view of the Milky Way galaxy. Newly discovered gamma-ray jets (pink) extend for 27,000 light-years above and below the galactic plane, and are tilted at an angle of 15 degrees. Previously known gamma-ray bubbles are shown in purple. The bubbles and jets suggest that our galactic center was much more active in the past than it is today.
Today the Milky Way Galaxy is a relatively quiet place. Our galaxy has grown up, and intense activity seen in other galaxies is a thing of our past. But scientists have long assumed the past was more hectic. A new study finds ghosts of past activity in the form of twin jets spat into space from the Milky Way’s central black hole.
Unlike our quiescent galaxy, active galaxies have cores that glow brightly, powered by supermassive black holes swallowing material and exciting the gas and dust around them to grow brightly in many wavelengths, from visible light to X-rays and gamma rays. Active galaxies also often shoot twin jets in opposite directions — beams of material thought to be directed by intense magnetic energy.
The new evidence of ghostly gamma-ray beams suggests that the Milky Way’s central black hole was much more active in the past.
“These faint jets are a ghost or after-image of what existed a million years ago,” said Meng Su, an astronomer at the Harvard-Smithsonian Center for Astrophysics (CfA), and lead author of a new paper in the Astrophysical Journal. “They strengthen the case for an active galactic nucleus in the Milky Way’s relatively recent past.”
Saturn
1. This is an example of a beautiful picture of Saturn taken by NASA’s Voyager 1 spacecraft in 1980. As you can see, the quality has improved significantly over the image captured by Pioneer 11. Both Voyager 1 and Voyager 2 made quick flybys of Saturn and then sped off into space. When Voyager 1 completed its flyby of Saturn, it sped off into the depths of space, while Voyager 2 went on to visit Uranus and Neptune as part of its Grand Tour of the Solar System.
2. It’s not the best picture, but you’re looking at one of the first ever images of Saturn captured up close by NASA’s Pioneer 11. During its mission, Pioneer 11 passed just 20,000 km above the cloud tops of Saturn, and captured the first close-up images of Saturn.
Voyager and Cassini
1. Jupiter Portrait
Here’s a spectacular photo of Jupiter taken by the narrow angle camera flying onboard the NASA’s Cassini space craft. Jupiter is one of the four gas giants in the solar system.
2. Jupiter’s Great Red Spot Region
This is a close-up photo of the Great Red Spot of Jupiter. The Great Red Spot is actually a storm located south of Jupiter’s equator. This photo was taken by the Voyager 2 spacecraft in 1979.
(Source: news.discovery.com)
(Source: news.discovery.com)
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Comet
Comet Hale–Bopp, as seen on 29 March 1997 in Pazin, Croatia
Astronaut Edward White floats in zero gravity of space northeast of Hawaii, during the first-ever spacewalk for an American, on June 3, 1965, during the flight of Gemini IV. (NASA/JSC/ASU) #
Galileo moon phases
Galileo’s sketches and observations of the Moon revealed that the surface was mountainous.
Home Sweet Home
Einstein at his home in Princeton, New Jersey.
Space shuttle Discovery is lugged out to launch pad 39A at the Kennedy Space Center on January 17, 1997. (NASA)
Astronauts Drive on the Moon
1971: Apollo 15 astronauts David Scott and James Irwin drive the Lunar Roving Vehicle on the surface of the moon. It’s the first off-planet automobile ride.
