Did You Know: Diffraction Sp­­ikes

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Did you know the spikes around bright stars result from certain telescope designs?

Learn more about diffraction spikes:

Produced by the Space Telescope Science Institute’s Office of Public Outreach in collaboration with NASA’s Universe of Learning partners: Caltech/IPAC, Center for Astrophysics | Harvard & Smithsonian, and NASA Jet Propulsion Laboratory.
Video imagery:
  • Image of Globular Cluster NGC 6397: NASA, ESA, and H. Richer (University of British Columbia)
  • Animation of different telescope’s primary mirrors and struts, and their influence: STScI
  • Cropped image of Herbig-Haro 46/47: NASA, ESA, CSA, J. DePasquale (STScI), A. Koekemoer (STScI)
  • Collage of different telescopes’ diffraction spikes: NASA, ESA, CSA, J. DePasquale (STScI), A. Koekemoer (STScI); NASA, ESA, and T. von Hippel (Embry-Riddle Aeronautical University); G. Kober (NASA/Catholic University of America); A. Bellini (STScI)
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Title, Did You Know?
Diffraction Spikes.
An image of stars in a galaxy.
Text, The spikes around bright stars result from certain telescope designs. Although these stars look like twinkling points of light, the lines extending from their centers are part of the observation, not the stars. NASA, ESA, and H. Richer (University of British Columbia).
Primary Mirror - Influence. Six illustrations of designs resulting from telescope diffraction: triangle to six-spoke star; circle to concentric circles; hexagon to five-spoke star.
Primary Mirror - Shapes. Hubble. Spitzer. Webb; Roman. These spikes result from light interacting with the telescope's primary mirror ... and its secondary mirror's support structures, called struts or vanes.
Strut Influence. Spike created perpendicular to strut. Four illustrations of spikes within a circle. Colored lines intersecting within the circles. Text, Spikes overlap at focus. The lines transform into dotted lines. Text, Resulting spike pattern. The intersecting lines become white lines emanating from the center.
Text, Primary Mirror and Strut Influence. Four illustrations of the spiking white lines alongside a thumbnail picture of the Strut Influence.
Text, Diffraction spikes are easiest to see surrounding the brightest compact objects in an astronomical image. NASA, ESA, CSA, J. DePasquale (STSc I), A. Koekemoer (STSc I).
In an animation, certain stars in a galaxy are circled. Text, while the spikes around dimmer objects and those more spread out are much harder to notice.
Images displaying diffraction spikes produced by four telescopes: Hubble, Spitzer, Webb, and Roman (simulation).
Text, Next time you look at an image of space, take note of these visual marks imprinted by some telescopes as they observe our wondrous universe.