By Joe Rao Space.com
A newly discovered comet will soon be gracing our evening sky.
On Sept. 10, Vladimir Bezugly of Dnipro, Ukraine was examining online images of a low-resolution public website showing images obtained during Sept. 5-9 with the Solar Wind Anisotropies (SWAN) camera on the Solar and Heliospheric Observer (SOHO) spacecraft. That’s when he discovered a moving object, resembling a bright blob, close the sun. The blob turned out to be a comet. A bright comet.
In fact, as Bezugly later noted: “In my memory, this is one of the brightest comet discoveries ever made on SWAN imagery,” adding, “the 20th official SWAN comet so far.” Since Bezugly’s first sighting, many other amateurs — primarily in the Southern Hemisphere — have viewed it. The comet has since received a formal IAU designation on Sept. 15 as Comet C/2025 R2 (SWAN).
Astronomers rely on magnitude to determine brightness. Magnitude is a numerical scale used in astronomy to measure the apparent brightness of celestial objects, where lower numbers indicate brighter objects, and higher numbers indicate dimmer objects. The brightest stars are magnitude 0 or +1, while the limit for naked-eye visibility under a dark, non-polluted sky is considered to be magnitude +6.5.
A consensus of the most recent observations of comet SWAN indicated a magnitude of +7, which places it just out of the reach of naked-eye visibility under dark, moonless skies. Good binoculars, however, can readily bring it into view.
The typical description of the comet by those using binoculars and small telescopes is a small, condensed head or coma with a thin, faint tail extending for roughly 2 degrees.
An orbit based on 60 different observed positions between Sept. 12 and 14, 2025 has been calculated by Syuichi Nakano of the Central Bureau for Astronomical Telegrams. He finds that the comet passed perihelion — its closest point to the sun — on Sept. 12 at a distance of 46.74 million miles (75.20 million km).
