Comet SWAN (C/2025 R2) will pass 0.27 AU from Earth around Oct 20–21.
Comet SWAN, found in NASA SOHO data, will near Earth mid-Oct 2025, glowing green and visible after sunset
Photo Credit: Gerald Rhemann, Michael Jaeger
In mid-September 2025, an amateur in a NASA SOHO spacecraft data found a new comet, C/2025 R2 (SWAN). It turned the Sun and is already being brightened - by the end of September, it could be seen through the field glasses, and it was brightening very fast. The visitor will fly into the -3 degrees of Earth on approximately 20-21 October with an altitude of under 0.27 AU above the surface, potentially being seen by the naked eye with the help of dark skies. The observers are to watch the western horizon at dusk to see it.
According to NASA, SWAN has already brightened into binocular visibility. When the heat of the Sun melts its ice, a glowing coma and tail are created. The greenish gas tail of SWAN has been observed using telescopes. It will pass approximately 0.27 AU (about 40 million km) past Earth in October 2021. During closest approach, the comet could be visible to sharp-eyed people under very dark skies, but the view would be greatly enhanced with the use of binoculars or a small telescope.
SWAN will appear “near the western horizon after sunset”. It spends the early part of October in Libra near Alpha Librae (Zubenelgenubi); it is in Aquarius at the end of October. It is nearest to the earth on the 20-21 October (around 40 million km), hence these two days are the best days to watch.
The comet can grow up to approximately magnitude +5 (or just naked-eye viewable in dark skies with the perfect telescopes); therefore, the use of binoculars will be a plus. It begins at the southern sky and moves northwards in mid-October.
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