Comet Nishimura, discovered earlier this year, has made its closest approach to the Sun and surprisingly survived the journey. The kilometer-sized comet, which has a green coma and a tail, is believed to originate from the Oort Cloud, a distant collection of icy objects at the edge of our solar system. Despite its close encounter with the Sun, which occurred deep within the orbit of Mercury and brought it within 0.22 astronomical units (AU), the comet is expected to remain intact. It will return to Earth 435 years later, according to NASA.
The comet, named after the Japanese astronomer who discovered it, was first spotted on Aug. 11 by amateur Japanese astronomer Hideo Nishimura during long-exposure photographs with his Canon digital camera and 200 mm telephoto lens. It subsequently moved into the inner solar system and, on Sept. 17, will reach perihelion, the point in its orbit at which it is closest to the Sun. At perihelion, the comet will be 27 million miles from the Sun, or some 40 percent closer to our star than Mercury is. This is a safe distance, which means the comet should be bright enough to be visible with binoculars or even the naked eye, depending on weather, light pollution, and how much it brightens over the next few days, explains Paul Chodas of Sky and Telescope.
If Nishimura brightens enough, it should also be possible to see with the naked eye in a few weeks as it passes by the constellation Leo in the predawn sky, reports Forbes. Observers in the Southern Hemisphere will have a perfect chance to spot it since it will be positioned about 30 minutes before sunrise.
Nishimura may also be associated with the upcoming Sigma-Hydrid meteor shower in mid-December, which occurs when Earth sweeps near the comet’s path. The meteor display is usually produced by pint-sized pieces of leftover comet debris that burn up as they enter Earth’s atmosphere. The debris comes from the leftover tails the comets shed as they leave our solar system. Astronomers think that if Nishimura is related to the Sigma-Hydrid meteor shower, it could replenish its tail and produce a meteor show in December.
Until then, though, the comet will only be visible in dark skies away from city lights. A pair of binoculars should be sufficient to pick up its slow movements across the night sky. You can check out a detailed chart from Sky and Telescope to find out where it will be in the constellations of Leo and Gemini at sunset and sunrise over the coming weeks.
