Tuesday, July 21, 2020

Neowise--A Sky Spectacular

Currently we have an unusual visitor from outer space—Comet Neowise—an acronym named after Near-Earth Object Wide-Field Infrared Survey Explorer.

Natural sky “spectaculars” infrequently occur, unless we include sunrises, sunsets, motions and phases of the Moon, pinwheeling of the stars around Polaris daily, and weather events connected with a multitude of changing atmospheric conditions. Observers may categorize such daily events as spectacular in their own right. These events provide coherence, beauty, interest, and appeal. Comet appearances, however, provide a superlative ‘spectacular.’ 

In this day of emphasis on the out of the ordinary, visible comets could be considered ultra-spectacular. Solar System comets are unpredictable visitors. Many millions of comets originate in the Kuiper Belt beyond Neptune. This comet probably orignated beyond the Kuiper Belt where there may be a trillion such objects. These globs of frozen gases and dust orbit the Sun, some rarely falling close to the Sun in their elliptical orbits. When they reach the inner solar system the Sun’s heat vaporizes the frozen gases while the solar wind drives the gases and dust away from the Sun, forming a visible tail. After reaching perihelion, their closest approach to the sun, surviving comets are propelled back out to remote reaches of space from which they originated. Comet Neowise was discovered on March 27, 2020. It is not scheduled to make a return visit to the Sun for 6800 years according to mathematicians.

On July 19 we observed the sky just under the Big Dipper as evening darkness approached. For about 30 minutes, as the Dipper was slowly becoming visible, no trace of the comet appeared. Darkness finally enabled all the Big Dipper stars to come into view. Shortly, we caught a fleeting vision of the comet’s coma and tail. Within several minutes, we were sure we spotted Neowise. Averted vision, looking slightly to the periphery, was necessary rather than direct vision. Peripheral vision is more sensitive to dim objects. After a few minutes, binoculars revealed Neowise in its glory, but It remained an impressive naked eye object.

Comet Neowise is the most impressive naked eye comet visible in the past 23 years. In 1996 Comet Hyakutake was termed the Great Comet of 1996. It was visible for only a brief few days, speeding by Earth quickly because of its close approach. Comet Hale-Bopp, now known as the Great Comet of 1997 was even more impressive. It provided 18 months of visibility. My father, at age 88, was once able to view the comet through an Astroscan telescope with eyes weakened by macular degeneration. I provided an evening discussion and viewing opportunity for my students, aided by my pastor’s tracking telescope. We were able to see jets of gas spiraling away from the coma. The spiral jets were caused by the rotation of the comet body.

Many observers count Neowise, Hale-Bopp, and Hyakutake as the three most spectacular comets to become visible in their lifetime. The current “Neowise—A Sky Spectacular” post should be added to the collection of our former posts from late October to Early November 2019 in which we recounted many personal memories of sky spectaculars. The natural world, including the phenomena of comets, declares “the glory of God” and reveals “the work of his hands” (Psalm 19:1-4). Our July 19 observation of Comet Neowise took place on a startlingly beautiful, clear summer night. The MIlky Way was brilliant overhead in all its glory—somewhat unusual on a mid-summer day when light pollution is a handicap to star-gazing in many locations. (Our neighborhood has strict ‘dark sky’ regulations.) Neowise is a fleeting treat for comet-watching stargazers, providing motivation for a detailed study of one of many fascinating wonders of God’s creation.