APOD - New Comet SWAN25B over Mexico

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2025 September 16

New Comet SWAN25B over Mexico
Image Credit & Copyright: Daniel Korona

Explanation: A newly discovered comet is already visible with binoculars. The comet, C/2025 R2 (SWAN) and nicknamed SWAN25B, is brightening significantly as it emerges from the Sun's direction and might soon become visible on your smartphone -- if not your eyes. Although the brightnesses of comets are notoriously hard to predict, many comets appear brighter as they approach the Earth, with SWAN25B reaching only a quarter of the Earth-Sun distance near October 19. Nighttime skygazers will also be watching for a SWAN25B-spawned meteor shower around October 5 when our Earth passes through the plane of the comet's orbit. The unexpectedly bright comet was discovered by an amateur astronomer in images of the SWAN instrument on NASA's SOHO satellite. The comet is currently best observed in southern skies but is slowly moving north. The featured image was captured at sunset three days ago just above the western horizon in Zacatecas, Mexico.

Tomorrow's picture: sagittarius triplet

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Amber Straughn Specific rights apply.
NASA Web Privacy, Accessibility, Notices;
A service of: ASD at NASA / GSFC,
NASA Science Activation
& Michigan Tech. U.

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APOD - Earth During a Powerful Solar Storm

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2025 September 15

Earth During a Powerful Solar Storm
Video Credit: NASA's SVS, SWRC, CCMC, SWMF; T. Bridgeman et al.

Explanation: Can our Sun become dangerous? Yes, sometimes. Every few years our Sun ejects a scary-large bubble of hot gas into the Solar System. Every hundred years or so, when the timing, location, and magnetic field connections are just right, such a Coronal Mass Ejection (CME) will hit the Earth. When this happens, the Earth not only experiences dramatic auroras, but its magnetic field gets quickly pushed back and compressed, which causes electric grids to surge. Some of these surges could be dangerous, affecting satellites and knocking out power grids -- which can take months to fix. Just such a storm -- called the Carrington Event -- occurred in 1859 and caused telegraph wires to spark. A similar CME passed near the Earth in 2012, and the featured animated video shows a computer model of what might have happened if it had been a direct hit. In this model, the Earth's magnetopause becomes so compressed that it went inside the orbit of geosynchronous communication satellites.

Tomorrow's picture: stellar cathedral

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< | Archive | Submissions | Index | Search | Calendar | RSS | Education | About APOD | Discuss | >

---

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Amber Straughn Specific rights apply.
NASA Web Privacy, Accessibility, Notices;
A service of: ASD at NASA / GSFC,
NASA Science Activation
& Michigan Tech. U.

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This is an automated email. If you notice any problems, just send me a note at gtracy@gmail.com. You can add and remove email addresses to this distribution list here, https://apodemail.org.Unsubscribe