Humboldt County, California
If you have not seen Comet NEOWISE in the northwest skies after dark, then you really must treat yourself. It has rounded the sun in its orbit now, and the farther from the sun it travels the dimmer it will be. Though its closest approach to Earth will be on July 23, it will also be farther from the sun, with the net result that it seems to be dimming by my observations. Go see this amazing celestial object; you’ll wait around 6,800 years for its next pass. You don’t want to miss this rare spectacle; go out soon.
Comet NEOWISE has been visible to the naked eye above the northwest horizon after dark for the last week or so, as seen from our position on California’s North Coast. Revolving around the North Star, in the evening we can find it beneath the Big Dipper as it slowly sinks in the northwest. The comet does set during the night a little after 1:00 a.m., so don’t be too late. Its movement continues beneath the horizon during the night, until later in the morning it is rising again to the northeast. It has been visible until dawn until recently, but no longer. To view it after sunset, be patient until after 10:00 p.m. The later the better, because while there is much sunset glow in the sky, the comet blends in very well and is difficult to distinguish. After 10:30 p.m. is optimal viewing.
What is a comet, and why do we see it? Comets are made of ice, rock and dust, like a dirty snowball. The ice may comprise any of a number of gases, frozen into a solid state in the icy blackness of space. As comets approach the sun, the sun’s energy acts on the comet’s surface, causing molecules of the ice to sublimate, or become gas again without going through a liquid state. As this happens, some larger particles of dust and debris making up the comet nucleus, or solid center, are blown outward into the surrounding space. This combination of gasses and larger particles surrounding the nucleus makes the hazy head, and forms the tail(s).
We can see both tails of this comet once it is dark enough. The bluer tail is made up of those sublimated gas particles, and is pushed out into space by the pressure of the sun’s energy. This tail will always point away from the sun, as it is carried or “blown” away in the solar wind. The brighter, whiter or yellower tail is made up of the more solid debris, the dust and particles that slough off as the comet disintegrates in the sun’s energy. This trail will always follow the comet’s path. Thus the two trails will extend in different directions unless the comet is heading in toward the sun. As NEOWISE leaves the sun on its way back to the outer reaches of the solar system, the two tails will continue to diverge.
When you go out: The hills will be your best bet for the clearest air. Expect to find other people wherever you go. I have been to four different locations on four different nights, and there were always other stargazers, from one person at Friday night’s secluded location, to maybe 15 at another spot two nights before. Be ready to follow social distancing protocols; as I passed the turnout where the bigger group had been two days before, I saw that it contained many more people the second time. But in every case, it was rewarding to share this truly awesome celestial display with other people, whether or not I knew them.
NEOWISE is an acronym for Near-Earth Object Widefield Infrared Survey Explorer, the NASA kit that discovered the comet on March 27, 2020.
I want to thank and acknowledge the help of my colleague, College of the Redwoods Astronomy professor Jon Pedicino, for providing clarifying technical details on this comet and comets in general.
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Carol J Tudor says
Thank you, Carol. I appreciate it.