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--- blog:aardvaark:iotd [2020/06/28 08:53] – Phil Ide
+++ blog:aardvaark:iotd [2024/05/08 05:00] (current) – external edit 127.0.0.1
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 ~~NOCACHE~~
 ====== NASA Image of the Day ======
-Date: **Sun 28th June, 2020**\\
+Date: **Wed 8th May, 2024**\\
-Title: **Europa and Jupiter from Voyager 1**
+Title: **Visualization: A Black Hole Accretion Disk**
 === ===
-What are those spots on Jupiter? Largest and furthest, just right of center, is the Great Red Spot -- a huge storm system that has been raging on Jupiter possibly since Giovanni Cassini's likely notation of it 355 years ago.
+What would it look like to circle a black hole? If the black hole was surrounded by a swirling disk of glowing and accreting gas, then the great gravity of the black hole would deflect light emitted by the disk to make it look very unusual. The featured animated video gives a visualization. The video starts with you, the observer, looking toward the black hole from just above the plane of the accretion disk.
-It is not yet known why this Great Spot is red. The spot toward the lower left is one of Jupiter's largest moons: Europa. Images from Voyager in 1979 bolster the modern hypothesis that Europa has an underground ocean and is therefore a good place to look for extraterrestrial life. But what about the dark spot on the upper right? That is a shadow of another of Jupiter's large moons: Io. Voyager 1 discovered Io to be so volcanic that no impact craters could be found.
+Surrounding the central black hole is a thin circular image of the orbiting disk that marks the position of the photon sphere -- inside of which lies the black hole's event horizon.
-Sixteen frames from Voyager 1's flyby of Jupiter in 1979 were recently reprocessed and merged to create the featured image.
+Toward the left, parts of the large main image of the disk appear brighter as they move toward you. As the video continues, you loop over the black hole, soon looking down from the top, then passing through the disk plane on the far side, then returning to your original vantage point. The accretion disk does some interesting image inversions -- but never appears flat. Visualizations such as this are particularly relevant today as black holes are being imaged in unprecedented detail by the Event Horizon Telescope.
-About 43 years ago, Voyager 1 launched from Earth and started one of the greatest explorations of the Solar System ever.
+ Singularity Impressive: It's Black Hole Week at NASA!
+<HTML><iframe width='1004' height='753' src='https://www.youtube.com/embed/l36UkYtq6m0?rel=0' frameborder='0' allow='accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture' allowfullscreen></iframe></HTML>
-Free Download: Voyager Posters
+//If you leave a comment below, please enter the date when referring to images. I can go back and fetch images for a specific date if you request it.//
-[https://apod.nasa.gov/apod/image/2006/EuropaJupiter_Voyager_2792.jpg|{{https://apod.nasa.gov/apod/image/2006/EuropaJupiter_Voyager_960.jpg?800|Click image to enlarge}}]
-\\
-Click the image for a larger view (opens in a new tab)
 ~~socialite~~
 ~~DISCUSSION~~