Astronomy Picture of the Day

Solis Lacus: The Eye of Mars

As telescopes around planet Earth watch, Mars is growing brighter in night skies, approaching its 2020 opposition on October 13. Mars looks like its watching too in this view of the Red Planet from September 22. Mars' disk is already near its ...

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Sonified: Eagle Nebula Pillars

Yes, but have you ever experienced the Eagle Nebula with your ears ? The famous nebula, M16, is best known for the feast it gives your eyes, highlighting bright young stars forming deep inside dark towering structures. These light-years long ...

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GW Orionis: A Star System with Titled Rings

Triple star system GW Orionis appears to demonstrate that planets can form and orbit in multiple planes. In contrast, all the planets and moons in our Solar System orbit in nearly the same plane. The picturesque system has three prominent stars, ...

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Filaments of the Cygnus Loop

What lies at the edge of an expanding supernova? Subtle and delicate in appearance, these ribbons of shocked interstellar gas are part of a blast wave at the expanding edge of a violent stellar explosion that would have been easily visible to ...

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Lightning over Colorado

Have you ever watched a lightning storm in awe? Join the crowd. Oddly, details about how lightning is produced remains a topic of research. What is known is that updrafts carry light ice crystals into collisions with larger and softer ice balls, ...

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Moon Pairs and the Synodic Month

Observe the Moon each night and its visible sunlit portion will gradually change. In phases progressing from New Moon to Full Moon to New Moon again, a lunar cycle or synodic month is completed in about 29.5 days. They look full, but top left to ...

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Moon over Andromeda

The Great Spiral Galaxy in Andromeda (also known as M31), a mere 2.5 million light-years distant, is the closest large spiral to our own Milky Way. Andromeda is visible to the unaided eye as a small, faint, fuzzy patch, but because its surface ...

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Enceladus in Infrared

One of our Solar System's most tantalizing worlds, icy Saturnian moon Enceladus appears in these detailed hemisphere views from the Cassini spacecraft. In false color, the five panels present 13 years of infrared image data from Cassini's Visual ...

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ISS Transits Mars

Yes, but have you ever seen the space station do this? If you know when and where to look, watching the bright International Space Station (ISS) drift across your night sky is a fascinating sight -- but not very unusual. Images of the ISS ...

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Equinox in the Sky

Does the Sun set in the same direction every day? No, the direction of sunset depends on the time of the year. Although the Sun always sets approximately toward the west, on an equinox like today the Sun sets directly toward the west. After ...

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