09-04-2025
Amateur astronomer discovers bright green comet SWAN25F — and you can see it too
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An amateur astronomer has discovered a bright green comet dive-bombing toward the inner solar system. The emerald-colored object will slingshot around the sun in less than a month, when it could become visible to the naked eye — but anyone with decent backyard gear may be able to see it now.
The new comet, dubbed SWAN25F, was discovered April 1 by Australian amateur astronomer Michael Mattiazzo, who noticed the comet in photos captured by the SWAN camera on the European Space Agency's Solar and Heliospheric Observatory (SOHO) spacecraft, according to
Multiple astronomers have since confirmed SWAN25F's existence, but the comet has not yet been officially recognized by NASA's Minor Planets Center. As a result, there are still large gaps in what we know about this object's size, origin, distance, speed and orbit. But researchers have started to piece together its trajectory through the solar system and believe it will reach perihelion — its closest point to the sun — on May 1 and reach a minimum distance of around 31 million miles (50 million kilometers) from our home star.
News of the potential new comet spread quickly, enabling multiple astrophotographers to capture striking pictures of the comet just days after it was discovered, Live Science's sister site reported. The green comet has also been snapped by the Virtual Telescope Project in Manciano, Italy.
One of the best photos of SWAN25F so far was captured by astrophotographers Michael Jäger and Gerald Rhemann from Weißenkirchen, Austria (see above).
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Based on that photo, SWAN25F likely has a tail spanning up to 2 degrees across the night sky, Jäger told Live Science. That is quite significant for a comet this far from the sun, although the tail is currently quite faint, he added.
The comet's emerald glow is likely the result of dicarbon — a form of carbon where a pair of atoms are double-bonded to one another, which has been known to give off a green color in other comets.
Initial observations of SWAN25F revealed that the comet had an apparent magnitude of around +10, but it has quickly brightened to less than +8. (Apparent magnitude is measured relative to the brightest objects in the night sky, which have a value of zero. The brighter the comet gets, the lower its magnitude will get.)
"The comet appears to be brightening quite quickly," Nick James, the director of the comets section at the British Astronomical Association, told earlier in the week. "It is too early to predict what the peak brightness will be. We need a few more days of observations to confirm the current trend, but it should become at least a binocular object."
But James' prediction has already come true, as the comet can now be seen with a decent pair of stargazing binoculars or a decent telescope, reported. The website has also mapped where the comet can be seen over the next few days.
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The comet will continually brighten as it approaches perihelion, and Jäger predicts that it could peak at around +5, which would make it visible to the naked eye. However, the comet's position puts it close to the horizon in the night sky, which could make it hard to spot.
As researchers continue to study SWAN25F, it will become clearer when and where the comet will be most visible.
