In today's image, we see the giant sunspot group AR 3664 which is currently crossing the face of the Sun. Sunspots are active regions on the Sun, slightly cooler than the surrounding surface. They are also associated with solar flares and coronal mass ejections when can affect us here on Earth and also contribute to auroral activity.

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This Podcast is an authorized New Media Mirror Site for APOD. You can access the image and website directly at: Astronomy Picture of the Day. You can use the archive link below the image to select the photo corresponding to the date of this podcast.

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