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This starry image of the Nasa/THIS The Hubble Space Telescope represents NGC 6717, which is over 20,000 light years from Earth in the constellation Sagittarius. NGC 6717 is a globular cluster, a roughly spherical collection of stars closely linked by gravity. Globular clusters contain more stars in their centers than their outer fringes, as this image clearly demonstrates; the sparsely populated edges of NGC 6717 contrast sharply with the sparkling collection of stars at its center.
The center of the image also contains intruders closer to the house. Bright foreground stars near Earth are surrounded by intersecting diffraction peaks formed by starlight interacting with structures supporting the Hubble secondary mirror.
The area of the night sky that contains the constellation Sagittarius also contains the center of the Milky Way, which is filled with light absorbing gas and dust. This absorption of light – which astronomers call extinction – makes studying globular clusters near the galactic center a challenge. To determine the properties of NGC 6717, astronomers relied on a combination of the Hubble Wide-Field Camera 3 and the Advanced Survey Camera.
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