SUSSEX COUNTY, NJ - Not since Hale-Bopp in 1997 has a comet been so visible to Northern Hemisphere viewers. Comet NEOWISE, discovered by the Near-Earth Object Wide-field Infrared Survey Explorer mission, was found only last March as it began to enter the inner solar system. The icy interloper swung around the sun back in early July, and it is now making a swift exit towards the outer solar system, with a relatively close pass of Earth scheduled in the coming days. Calculated to have inbound orbital period of 4,400 years, the comet’s velocity was increased by interaction with the sun, and astronomers have projected it will next return some 6,700 years from now.
Barring a wait of several millennia, the best chance to see the ‘dirty snowball’ is over the next few days, as the comet makes its nearest pass to Earth on Thursday, July 23. Right now, comet NEOWISE can be found in the post-dusk sky, beneath the Big Dipper. An observation on July 20 showed it is directly below the lowest part of the ladle, although the comet will appear to gradually arc upwards towards the left of the constellation over the coming days. At the same time, the moon will wax and become brighter, and so viewing conditions will likely deteriorate by next week as the comet fades in the lunar glow.
In most urban areas, the best way to view comet NEOWISE is with a set of binoculars, although once found it can occasionally be resolved with the naked eye. Some cell phones with a ‘night mode’ setting appear able to produce grainy images the comet, although a capable point-and-shoot camera with a few factors of magnification can probably photograph it with several seconds of exposure. For optimal comet spotting, avoid light pollution as much as possible, and find a location with relatively unobstructed views towards the northwest. The comet is relatively low on the horizon and can be easily masked by tall buildings and trees.
Dr. Daniel J. Ciarletta is a graduate from the Environmental Science and Management program at Montclair State University and a longtime resident of Hawthorne. He has more than a passing interest in the geology, geography, and history of New Jersey, and is also an avid hiker.