A rare solar wind burst sliced off Comet Lemmon’s glowing ion tail, captured by Brennan Gilmore.
Comet tails form from solar wind; ion tail points away, dust tail curves, sometimes cut off by flares
Photo Credit: NOAA
Brennan Gilmore captured a dramatic time-lapse on Oct. 2 showing the Sun's charged particles tearing away a large piece of Comet Lemmon's tail. Comet Lemmon, discovered in January 2025, has brightened rapidly as it nears a late-October flyby of Earth. The images show the comet's glowing green coma and long luminous tail. In this rare “disconnection event,” a gust of solar wind severed part of the comet's ion tail, creating a gap in the tail.
According to NOAA, the tails of the comets are powered by the solar wind – a continuous flow of charged particles from the Sun. As the Sun heats the ice in a comet, gas and dust are released, which form the coma (an atmosphere) around the nucleus.
The gas (ion) tail, which is usually greenish in colour due to carbon compounds like C2, is forced to go in the opposite direction to the Sun, while the dust tail is the one that remains attached to the comet but is longer and curved. A disconnection event is what astronomers refer to when the ion tail is completely cut off by a flare of solar wind.
On Oct. 2, Gilmore captured these pictures from Virginia by means of a Takahashi Epsilon 130D Newtonian telescope in conjunction with a ZWO astronomy camera. The pictures distinctly present Lemmon's vividly green coma (the part of the comet that glows) and a lengthy tail following the comet.
In the interval between the pictures, a burst of solar wind removed part of the ion tail; thus, a visible void in the tail can be seen. It is practically unheard of that a photographic record of such a clearly resolved comet tail-disconnection event exists.
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